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[Articles Home]  [Add Article]  

Convert Tube Receivers to Solid State

K4VRP (KV4JT) on June 24, 2013
View comments about this article!

It is sad to see the old tube radios relegated to the attic, basement or barn to deteriorate into useless junk. About three years ago I began purchasing Hammarlund and Hallicrafters receivers and converting them to 100% solid state. I have successfully converted HQ-100, 110, 145, 170 Hammarlund radios and S-85, SX-99, SX-100 Hallicrafters radios. There is no manual on how to do this so I started from scratch and discovered the secrets on my own.

A converted radio has many advantages:
1. No tubes to replace.
2. No heat.
3. Very little wattage.
4. Less drift.
5. No high voltage to kill you.
6. Newer type capacitors seldom fail.

All the old troublemaking parts are removed such as the power transformer, electrolytic filter cap, all tubes, all paper caps, most of the carbon resistors. The dial lamps are replaced with LED's.

The replacement parts include low cost caps, resistors, transistors, 24v power supply, chokes etc. The cost of the conversion is about the cost of a set of used tubes or around $50.00 or so.

The only problem is that only an experienced tech can accomplish a conversion. You must have a signal generator, o-scope, and tools. It is not a beginners project because it will involve re-alignment and possible troubleshooting.

I have not seen a tube model receiver yet that could not be converted to solid state. The advantages are enormous and it can go a long way to saving many of the old radios that are not collectors items. All of such radios purchased on E-Bay require repairs and parts replacement anyway and are not worthy of being part of a collection.

Tubes and associated higher voltage parts are becoming difficult to get and one day will be nearly impossible. So why not?

I have not yet published any diagrams or instructions yet. I will release all of the information whenever I am satisfied that it is bullet proof. It won't be long.

Member Comments:
This article has expired. No more comments may be added.
 
Convert Tube Receivers to Solid State  
by RADIOPATEL on June 24, 2013 Mail this to a friend!
Dear OM K$VRP

If shall be very much impresive if you can post some photos of converted receivers.

Thanks and Regards

Dinesh Patel VU2DCI

 
RE: Convert Tube Receivers to Solid State  
by WA7KGX on June 24, 2013 Mail this to a friend!
I experimented with converting parts of radios to solid state in the 60s and 70s. Replacing the RF amp in an FM tuner with a FET improved its reception.

Another conversion I tried disappointed me.

The vacuum tube circuits were designed around the impedances of the tubes. In particular, pentodes have a very high output resistance. A FET/bipolar cascode pair might be best.

Replacing tubes with higher gain transistors my lead to unwanted regeneration or oscillations.

A good first step might be to add a solid state product detector.
 
RE: Convert Tube Receivers to Solid State  
by AA4PB on June 24, 2013 Mail this to a friend!
A converted radio has many advantages, but it has one major disadvantage. It destroys the historic value of the radio.
 
RE: Convert Tube Receivers to Solid State  
by KG4RUL on June 24, 2013 Mail this to a friend!
I don't think creating "FrankenRadios" is a good thing. Would converting a a classic Model T sedan to a hybrid drivetrain be the right thing to do? They are what they are.
 
Convert Tube Receivers to Solid State  
by K1CJS on June 24, 2013 Mail this to a friend!
Hey, to each their own. If you had a keepsake radio that you wanted to keep AND use, a project like this may be nice to contemplate. Also, if you wanted a project that was unique and yielded something that you could say was 'yours,' something like this may fill the bill.

But just to convert older radios to solid state? I can think of better things to do with them, and not one of those things involves converting an older tube rig to a solid state 'potential headache' for someone else in the future.
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on June 24, 2013 Mail this to a friend!
This is a cool idea! Please post more info and pictures!
 
RE: Convert Tube Receivers to Solid State  
by KE5KDT on June 24, 2013 Mail this to a friend!
It is a great way to keep that piece of history telling its story for years to come. Seems odd that no one has a problem in getting a "new technology" knee or hip replacement, pacemaker or heart valve work, etc, etc. Isn't that the same thing on a human. Id rather function with replacement parts than to be immobile or pushing up daisies.
It is the beauty of ham radio, getting it to work when it otherwise would be a door stop or head to the dump.
Go for it.
Bob
 
Convert Tube Receivers to Solid State  
by K0CBA on June 24, 2013 Mail this to a friend!
Does anyone remember "Tubesters"?
 
RE: Convert Tube Receivers to Solid State  
by KX8N on June 24, 2013 Mail this to a friend!
I've never heard of this, but it sounds like a good idea. I would be against converting a WORKING vintage radio, but if it's out of commission and can't be restored with attainable parts then it would be worth it to get it back on the air. This could be a new class of radio's altogether. You could have vintage, solid state, software defined, and now hybrid. Sounds very much in the spirit of amateur radio in my opinion.
 
Convert Tube Receivers to Solid State  
by NY4Y on June 24, 2013 Mail this to a friend!
Anyone remember 'Fetrons'? They were plug in replacement JFET devides to replace tubes and came out about 35 years ago. If one could design direct plug in replacements for tubes it might be a good way to replace tubes and get the radios working again.

Personally, I find there really aren't that many bad tubes in radios, mostly the components around them need replacement.

 
Convert Tube Receivers to Solid State  
by KZ5A on June 24, 2013 Mail this to a friend!
This is a really bad idea. If you want a SS radio just buy a SS radio, or build one. Trashing vintage rigs for grins is a sad thing to see.

And the intimation about limited availability of tubes and parts to do proper vintage restoration is malarkey.

There are plenty of hams around with the experience and resources to restore vintage rigs to their former glory without butchering them. If you want to operate a vintage rig but do not have those restoration skills, just look around for one someone else has restored, there are plenty of them around these days.

73 Jack KZ5A

 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on June 24, 2013 Mail this to a friend!
Jack KZ5A: What someone does with HIS OWN radio is NONE of your business.
 
Convert Tube Receivers to Solid State  
by K0IC on June 24, 2013 Mail this to a friend!
I think this option should be available when parts/tubes become too pricey. Or, if the alternative is to junk the radio ahead of its time. High voltage electrolytic capacitors are becoming expensive, as are rewinding transformers. I am sure there always will be those who have deep pockets who can afford whatever it costs to keep electronics original, even if they have to make the parts.
 
Convert Tube Receivers to Solid State  
by KE4KE on June 24, 2013 Mail this to a friend!
I have always liked the idea. Sure save a few for posterity, but it makes a lot of sense. I like the old large boxes and controls. A good example of a modern device is the GE SuperRadio. It is in a large box with a decent speaker and large tuning knob.
 
RE: Convert Tube Receivers to Solid State  
by WN2C on June 24, 2013 Mail this to a friend!
It won't glow in the dark and real radios glow in the dark!

Rick WN2C
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on June 24, 2013 Mail this to a friend!
Throw some LEDs in the box and it will glow in the dark.
 
RE: Convert Tube Receivers to Solid State  
by WX7G on June 24, 2013 Mail this to a friend!
Sacrilege.
 
RE: Convert Tube Receivers to Solid State  
by VA3AEX on June 24, 2013 Mail this to a friend!
Lots of work, and wouldn't think it was worth the effort. Why not build a new receiver where you are not impeded by design considerations made around the use of tubes.
 
Convert Tube Receivers to Solid State  
by K3OWZ on June 24, 2013 Mail this to a friend!
Sacrilege.

 
Convert Tube Receivers to Solid State  
by KE7TMA on June 24, 2013 Mail this to a friend!
Some day the choice will have to be made between converting tube radios to more modern technology, or having a large and expensive paperweight. Certain vital tubes will continue to go out of production as time goes on, and unless you have your stockpile of them in order BEFORE they are discontinued, you're unlikely to get replacements. Manufacturers typically don't warn people well in advance when something goes out of production.

There may develop a cottage industry where people make tubes in small numbers, but the quality control is likely to be lower and the more exotic tubes will not likely be made even by such bespoke outfits.

So, all of you naysayers, I hope you have at least a half dozen or so of every tube type you will ever need, or you will be begging somebody to transistorize your paperweights in the not-so-distant future.
 
RE: Convert Tube Receivers to Solid State  
by KV4JT on June 24, 2013 Mail this to a friend!
I am not advocating trashing radios for the fun of it. In order to restore an old tube radio that is in need of repair you may be forced to cannibalize another radio. Does anyone feel sorry for that radio? You are right about tube obsolescence. The tube sets available on E-Bay are used tubes jerked out of other radios which are being cannibalized. I am offering an alternative to destroying a non working radio. There are plenty of restored radios around. There is no sense in making museum pieces out of all of them. When you transistorize a radio you can sell a lot of pulled parts on E-Bay for others to enjoy. I.E. tubes, transformers, chokes, clocks, dial light sockets etc. None of these parts are available new. I am producing diagrams and will distribute them along with parts lists and instructions. We must also be aware of the trend to install MODS. Most tube linear amps now have mods. Some of them even have been converted to different tubes and there are project boards available that allow you to upgrade and improve the operation of your tube linear. Nobody seems to complain about that. A transistorized radio properly converted will probably outlast any tube model of the same age. Thanks for your observations. I enjoy the feedback.

Charles, KV4JT
 
Convert Tube Receivers to Solid State  
by WA4KCN on June 24, 2013 Mail this to a friend!
Should one desire a solid state reciever, better off to buy or build one. Restore the tube receivers.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on June 25, 2013 Mail this to a friend!
"...Certain vital tubes will continue to go out of production as time goes on, and unless you have your stockpile of them in order BEFORE they are discontinued, you're unlikely to get replacements...."

Unlikely that you'll not be able to get replacements--but point taken. People who want to continue to use their older rigs WILL get the tubes needed to do so, and no matter what happens, tubes will be available for years yet--they'll just be hard to find. And if the want is there, there will be some manufacturer that will be willing to make those tubes--for a price.
 
Convert Tube Receivers to Solid State  
by JOHNZ on June 25, 2013 Mail this to a friend!
I own several classic cars (radios). We recently installed a modern (solid state) engine and transmission into a 1955 Chevrolet. Outwardly, it was still very much a crowd pleaser. The only tears shed were from a few auto mechanics (extreme technicians) who comprise maybe one-tenth of one-percent of the crowds who view the car every year. Get the analogy? Also similar to a wealthy art collector, who spends millions on a painting, only to hide it from public view. Oh, how we hams are such a small peculiar demographic.
 
RE: Convert Tube Receivers to Solid State  
by KF4HR on June 25, 2013 Mail this to a friend!
Perhaps like vintage automobiles there will someday be a class of vintage radios that fall into the "Resto-Mod" (Restoration/Modification) category. And just like vintage auto's, some will think they are great, while the purist will lean more toward historic originality.

On the plus side, the conversion process would be a fantastic technical learning experience. And watching a dead door-stop receiver come back to life would be great too.

On the down side, as the author points out, technical expertise would be key. Also the modified unit would probably only be valuable to the person who performed the mods or others with an equal level of technical expertise (should the mods eventually fail and need repair).

It would be interesting if someone took this idea a step further and started producing modification kits for vintage radio equipment, complete with full documentation so the unit could continue to be repaired in years to come.

Interesting topic.
 
RE: Convert Tube Receivers to Solid State  
by KA4KOE on June 25, 2013 Mail this to a friend!
Replacing 866's with 866AS' from RF Parts likely saved the high voltage transformer in my Valiant. Those 866 rectumfryers are a disaster waiting to happen.
 
Convert Tube Receivers to Solid State  
by KC2QYM on June 25, 2013 Mail this to a friend!
I assume that the conversion process could include a single IC based SW receiver board, amplifier, and the gutting of everything else; power supply and indeed all other circuitry and compenents. I guess you could retain the knobs. What about the variable capacitors for main tuning and bandspread? That said, after the conversion the radio will never sound or be the same as what a restored valved receiver is. To me, this conversion process is like those new solid state table radio copies of the 1930s/1940s designs...Phony in every way. I think that a non functional boatanchor is worth more just having it in your collection than butchering it in this way...However, if that's your thing go at it. No one has the right to stop you. Just my opinion.
 
RE: Convert Tube Receivers to Solid State  
by F8WBD on June 25, 2013 Mail this to a friend!
I don't think I would care to perform this type of surgery on radio amateur gear.

But, very interesting applied to old tube BC radios. I like the idea of restoring and converting a nice console, floor model radio. Put a great solid-state amp and cd player in it. Small, efficient speaker replacement. Then listen to my old 20's and 30's jazz cd collection.

Perfect retro fantasy.
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on June 25, 2013 Mail this to a friend!
KC2QYM: You are wrong, he is not talking about replacing everything with a circuit board. He is talking about replacing the individual tube stages with a solid state equivalent. He still uses the dials, knobs, variable tuning caps, etc... He is not gutting it.

 
RE: Convert Tube Receivers to Solid State  
by KA4KOE on June 25, 2013 Mail this to a friend!
There was a company awhile back that made plug in replacements for some of the more common receiver tubes. That would be the way to go, IMHO, that wouldn't involve the blasphemic butchery of the radio in question. Nice phrasing, 'eh?
 
RE: Convert Tube Receivers to Solid State  
by KA4KOE on June 25, 2013 Mail this to a friend!
And finally, why???

Once the odor of carbonized dust wafts off the glass tube envelopes and into your nostrils, you'll never entertain such thoughts again.

Solid state is irrelevant. No odor is irrelevant. Modifications are also irrelevant. Resistance is Futile, and you will accompany the followers of the true faith to Sector 0-0-1.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on June 25, 2013 Mail this to a friend!
Waaaait a minute--modifications are irrelevant? If we're talking about those guys, modifications certainly are relevant. After all, they do modify existing species! ;-)
 
RE: Convert Tube Receivers to Solid State  
by KV4JT on June 25, 2013 Mail this to a friend!
Most of the transistors used are MPF-102. They are very popular and if they become obsolete a replacement will definitely be available. The outside appearance of the converted radio does not change except for the color of the LED's which replace the dial lamps. The sound will be somewhat different with transistor replacement. You just cannot get the same sound out of transistors that you get from the tube/transformer combo. There are no such things as tube drop-ins except in a very few cases. These were tried years ago. I have tried them also. I can build plug in modules but they require modification of some of the under chassis parts which defeats the purpose of plug-in's. I only use plug-ins in areas where you cannot access the underside such as the oscillator in the Hammarlund HQ-100/110. Plug-ins are easy to make but it is less problematic in most cases to simply solder a transistor directly to the tube socket. The operation of the radio is transparent to the user. It is only when you look inside and see no tubes that you begin to realize something is different. The transistor circuitry is simplistic and easy to troubleshoot (without getting shocked with 300 or 400 volts). A lot of the work is in fixing the mistakes that Hammarlund caused. The IF transformers fail on practically all of them because the mica sandwich capacitors inside them lose contact and corrode. If you want a trouble free radio you have to dismantle the IF's and remove the micas and replace them with external fixed capacitors. That is a delicate operation but must be done even on the tube models. If you neglect to do that you will be very, very sorry in the long run. They will intermittently cause the radio to fade out partially or completely and you will wonder why. There is a very bright side to a converted radio when properly done. I will probably do a YOUTUBE video one day soon to show the world that it is real.
 
RE: Convert Tube Receivers to Solid State  
by K6AER on June 25, 2013 Mail this to a friend!
This is about the worst idea I can think of in the hobby. Older tube equipment was designed for the following:

• High impedance inputs.
• High voltage Anode to Cathode operation,
• Analog operation
• Impedance matching based on tube specifications.
• Available engineering technology of that period.
• Point to point wiring.
• Lots of string for band pointers.
• Large eye hook for anchor chain attachment.

Newer radios have the advantage of:

• Lower noise devices.
• Lower phase noise oscillators
• Higher efficiency power supplies and devices.
• Microprocessors and DSP processing.
• SMD construction.
• PCB’s
• Highly integrated displays.
• Can be carried by a single person.

To me this is a bit like putting a string bikini on Grandma. Some things you should not do.
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on June 25, 2013 Mail this to a friend!
KV4JT: Don't let these eHam BOZOs discourage you. It is a great idea. Please post more information and videos!
 
RE: Convert Tube Receivers to Solid State  
by KV4JT on June 25, 2013 Mail this to a friend!
I'm constantly amused by the nay sayers.
 
Convert Tube Receivers to Solid State  
by KA8SEP on June 25, 2013 Mail this to a friend!
This is funny, I asked this question on a forum at another site. I got a lot of technical reasons why it shouldn't be done but you are plugging along. my reason for asking about this was to take old designs and use modern parts to make them.

Good job


Ted - ka8sep
 
RE: Convert Tube Receivers to Solid State  
by KI4WGI on June 25, 2013 Mail this to a friend!
Sounds like some of the other debates I've seen in the past. I have a HW-101 I would never convert. But I have several junkers (including a HW)that would make quite a project. I have considered converting an old Navy TCS to solid state, and found an article where someone converted a BC-348. April 1977 of QST had an article on "Solid Tubes" by W5DA, also see Feb 77 for a conversion for a BC-221. Both articles were plug-in conversions. For starters I plan to convert an old 5 tube AM AC-DC set I have (and run it off 12 vdc).

Why do it? Because you can. Because what you would learn. Because you can never homebrew something that would look a good or be a well built (ok, I've sen a few homebrew jobs that floored me with the quality...). And as pointed out, some old rigs are already gutted and this would give them new life.

It sort of like learning code. Some love it. Others got lost after they got rid of line numbers.
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on June 25, 2013 Mail this to a friend!
@K6AER
Concerning grandma in a string bikini, tacky maybe, but grandpa still views grandma as the lovely young maiden he married many years ago.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on June 25, 2013 Mail this to a friend!
As I said--to each his own. But if the rig is dead and it would take quite a lot to rebuild it to original specs, why not turn it into a solid state rig? It would rejuvenate it, make a good conversation piece and provide experience and possibly a few lessons to boot.

But to take a working boat anchor, rip out it guts and remake it just for the heck of it.... I would tend to agree with the people who say no, don't do it.
 
RE: Convert Tube Receivers to Solid State  
by W4OP on June 25, 2013 Mail this to a friend!
Being an actual restorer, I am constantly shocked by what others, with too little knowledge and tools have done to some beautiful BA's.

If your idea is to create new Tubesters (that is say a solid state replacement for a 6BE6 as an example) as was done many years ago, then go for it. But to start tearing up a boatanchor because for you, to restore it correctly is too time consuming, too complex or too deep for your pockets is a shame. I have to vote no. Pass it along to one of us who routinely solve these issues and love doing it. Take the money and go by a Grundig or some other noninteresting clone.

BTW, when the Collins S line receiver tubes were replaced with the Tubesters, parameters like BDR and IP3 got worse- so be careful in your designs.

Dale W4OP
 
RE: Convert Tube Receivers to Solid State  
by K6AER on June 25, 2013 Mail this to a friend!
Then grandpa's lost his glasses.
 
RE: Convert Tube Receivers to Solid State  
by W4FJT on June 26, 2013 Mail this to a friend!
Personally I wouldn't convert an entire radio front to back. Having said that, I have an L600 Transoceanic with a "substitute" 1L6 tube (a solid state replacement built inside a same-size tube envelope). The 1L6 was made for just one purpose--early portable shortwave radios. If you could find one, they run up and over $100 on the Bay.

The AB battery is a cardboard box printed to look like a Zenith AB battery filled with alkaline AA cells to make up the required voltages. The pilot lamp battery is a cardboard cylinder printed to look like a Zenith 1.5 V cell, but contains an alkaline "C" cell on the inside.

Other than these substitutions, everything else is original. Looks and plays great. I have considered a white LED to light up the dial--then I could leave it on without melting the plastic dial face. If I do this, I will do it in such a way that the original can be restored easily. I think it would look good this way in a darkened room.

This is the only (slightly) modified radio in my boatanchor collection.
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on June 26, 2013 Mail this to a friend!
You may already know but just thought of something learned way back. If replacing paper capacitors with film capacitors, no need for the uF value to be identical. Most likely you are within the radio's factory specs if you are +/- 10% but do check the replacement capacitor's working voltage to ensure it is equal to or greater than original paper capacitor. Just a thought from an old radio restoration guy.
 
Convert Tube Receivers to Solid State  
by KB4QAA on June 26, 2013 Mail this to a friend!
I think this is a poor idea, except for one-off experimentation. This is not something that should be generally encouraged.

Tubes are not in short supply, most tubes will last decades of routine use. The only thing being preserved is the front panel, the rest of radios' history and functioning is being hacked and destroyed.
 
Convert Tube Receivers to Solid State  
by KO0KY on June 26, 2013 Mail this to a friend!
I've seen this done a few times, specifically on some Zenith Transoceanic models and an old Navy receiver. It works great, in most cases. If one uses OpAmps, the input and output impedances are similar, so the conversion is not that involved. One problem, however, keeps popping up: The capacitances of tube elements are quite different from the capacitances of solid state devices. That can throw off the dial calibration, quite a bit in some cases.
 
I don't understand the purpose?  
by KASSY on June 26, 2013 Mail this to a friend!
One of the hams in the largest club I belong to specializes in refurbing Drakes. I asked him if it's hard to get tubes, and he says it really doens't matter. It's very rare, he says, to find a bad tube. The exceptions are audio output tubes in receivers, and drivers/finals in transmitters.

Most problems he said are dirty tube/socket pins, switches, connectors, and potentiometers. Next on the list are things out of alignment, and then drifted carbon comp resistors.

To be honest, the list of parts that the OP listed sounded like it included everythign. If you're replacing all the tubes, caps and resistors, what is left that is vintage? Just the cabinet?

If that's enough, then I'll just hang pictures of the old stuff.

- k
 
Convert Tube Receivers to Solid State  
by K6CRC on June 26, 2013 Mail this to a friend!
Not sure this makes any sense. Old RXs are essentially useless when compared to modern rigs. So, spending time and energy to convert to SS simple destroys the value. Modern ICs, filters, mixers, etc. are lightyears ahead of anything in old RXs. Who wants a crappy solid state radio?

The true value in an old tube radio is the fun of restoration and the groups of people you meet while fixing or operating the radios.

You can add a FET preamp, or a digital readout without physical modification of the radio. Anything more than that is a waste of time and a sad destruction of a valuable relic, in my opinion.

 
Convert Tube Receivers to Solid State  
by WA1SEO on June 26, 2013 Mail this to a friend!
Way back in 1975 while learning about FET's in a High School Physics class, I decided to convert my Collins R-392 to a solid state rig. It was a great project and it turned out to be a very good performer. Along the way, I added some Collins mechanical filters for CW and SSB. I sold it after college and always wondered what happened to it.

Thanks for writing this article and bringing back some good memories.

Mike, WA1SEO
 
Convert Tube Receivers to Solid State  
by K8QV on June 26, 2013 Mail this to a friend!
It's like dropping a state-of-the-art Prius motor into your classic corvette chassis because you're afraid carburetors might become hard to find some day. So, is it still a Corvette? Hell no.
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on June 26, 2013 Mail this to a friend!
Anybody know of anywhere there are several hundred clean restored working pieces of tube-type ham radio equipment on display? Only place I know of is the ham radio museum in Asheville, North Carolina.
 
RE: Convert Tube Receivers to Solid State  
by W4OP on June 26, 2013 Mail this to a friend!
I don't believe there is a larger, more complete collection of working boatanchors anywhere. Check out W9EVT's "shack":
http://www.qrz.com/db/W9EVT

Dale W4OP
 
RE: Convert Tube Receivers to Solid State  
by W4OP on June 26, 2013 Mail this to a friend!
By the way, to the best of my knowledge, George has not converted any of them to solid state.

Dale W4OP
 
RE: Convert Tube Receivers to Solid State  
by KD8SAV on June 27, 2013 Mail this to a friend!
Holy cow!

That's one HUGE collection.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on June 27, 2013 Mail this to a friend!
Huge is right. Obsessive and pretty odd come to mind as well.
 
RE: Convert Tube Receivers to Solid State  
by W1JKA on June 27, 2013 Mail this to a friend!
As noted before isn't this akin to dropping in a V8,Hurst transmission and disc brakes into a Model T then going on weekend drives and classic car meets?Mean time grandpa is some po'd with tears in his eyes but grandson is having one hell of a fun time driving around in it.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on June 27, 2013 Mail this to a friend!
One of the rigs in hybrid era came out with a plug-in solid state board in their later models. I think the balanced modulator tube, or maybe a larger audio tube wasn't getting it done, so they went solid state with a plug-in board right from the factory. Maybe the FT-101 of some flavor?

 
Convert Tube Receivers to Solid State  
by W5GNB on June 27, 2013 Mail this to a friend!
Some years ago I converted a Heathkit HR-10B to all solid state. As an original Tube radio it was a piece of CRAP anyway.
After the Solid State conversion, it turned out to be a pretty good receiver thus eliminating all the inherent problems that were associated with it in it's Original life form.....
 
RE: Convert Tube Receivers to Solid State  
by PA0LPS on June 27, 2013 Mail this to a friend!
7. No warming-up time!

I think it is a great idea.
Can hardly wait to see the follow-up: How to do it?


 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on June 27, 2013 Mail this to a friend!
Just looked at the W9EVT collection, and it is very impressive. His collection is about the same size as the Ashville-Buncombe Technical Community College South Appalachian Radio Museum collection in Asheville NC, but the W9EVT collection would seem to have a slight edge in how it is displayed. The Asheville collection is limited to whatever space the college will allow it to have, and space is at a premium. One big difference, the Asheville collection is very accessible to the public. It is adjacent to an interstate highway, and parking on campus, as well as museum admission, are both free. My understanding is the W9EVT QTH can only be reached by limited ferry service to his island, a shame that it is not more accessible to the public. Does anyone know if W9EVT allows public access to his collection?
 
Convert Tube Receivers to Solid State  
by K1LLR on June 27, 2013 Mail this to a friend!
why the hell would anyone want 2 do dat?
 
RE: Convert Tube Receivers to Solid State  
by W8AAZ on June 27, 2013 Mail this to a friend!
Just to spite them, buy a nice 75A4, and convert it to solid state, with an LCD display. All the extra space inside will allow you to make the top hinged cover access to a new storage compartment where you can keep a solid state mini HF+6 transceiver that pops up when you open it. I want to see their faces!
 
RE: Convert Tube Receivers to Solid State  
by N4JTE on June 27, 2013 Mail this to a friend!
The article, such as it was, would have been much more effective if you actually documented and photographed what you are suggesting and evidently have done, so readers could be more motivated.
Bob
 
RE: Convert Tube Receivers to Solid State  
by WZ3O on June 28, 2013 Mail this to a friend!
Nay Sayers are everywhere take it with a grain of salt and do what you like... isn't it a HOBBY ... experimentation is what makes it great...opinions are one thing but to demean a fellow ham for his attempt to do something different well now that's absurd .... I bet most sqwauked abt SSB... and still complain abt NO CODE oh well .. get a life .....stop bitching abt any anything that doesn't fit into your version of reality....
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on June 28, 2013 Mail this to a friend!
@WZ3O
Yes, it is a hobby but a service first, per FCC rules & regs. With all due respect to you, just clarifying a point. Different subject, I like the ark cartoon on your qrz listing.
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on June 28, 2013 Mail this to a friend!
PLEASE DO post some videos and conversion information. This is very interesting.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on June 28, 2013 Mail this to a friend!
To all of those who think this is blasphemy......it's just stuff. If an owner wants to go in this direction, then let him knock himself out. If he's more interested in strangely hoarding pristine radios like that guy in Wisconsin, then he'll know full well that going solid state will affect the collectibility value. Radios like the Heath HR-10 mentioned earlier can only be helped by modifying them....they were terrible even in their day.

It's just stuff.
 
Convert Tube Receivers to Solid State  
by HFHAM2 on June 29, 2013 Mail this to a friend!
What you are suggesting turns a historic artifact into a piece of junk. You have no soul.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on June 29, 2013 Mail this to a friend!
"Historic"...well that's quite a stretch and for another debate. I can think of a few other adjectives for a lot of that stuff, and am so glad I'm past that era/phase. But to each his own.

What 's getting missed is that many of those guys contain their solid state and surrounding components onto small boards, or even point-to-point wired, and then it's all mounted on plug-ins that replace the tubes. The never rig's configuration never gets changed at all.

 
RE: Convert Tube Receivers to Solid State  
by K1CJS on June 29, 2013 Mail this to a friend!
I wouldn't go as far as saying a "historic" artifact. I DO say that a boat anchor in pristine condition, both physically and operationally, should not be considered for such treatment, but there again it's the owner's choice. All too many there days don't care about what they actually have, so if he wants to throw away the value of the rig, let him.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on June 29, 2013 Mail this to a friend!
Yeah, I hear (read) you, Chris. I'll be the first one to admit admiring a pristine Collins piece. Definitely a question of balance.

 
Convert Tube Receivers to Solid State  
by K1DA on June 29, 2013 Mail this to a friend!
I have an R4 C and a full complement of W5DA "solid tubes" I also have many sets of tubes for it. I like the instant warmup, and a slightly quieter receiver, but over all there isn't much difference. The W5DA products were tube shaped plug ins, BTW.
 
Convert Tube Receivers to Solid State  
by K1DA on June 29, 2013 Mail this to a friend!
The only tubes which are NOT plentiful for Drake 4 Line gear are the RF output tubes. (6JB6) THOSE are the ones which I would like to see solid state. ( and are the LEAST likely to be made such) Plenty of tubes around for Collins gear as well, INCLUDING 6146's. And yes, the impression created by some on here that you need 10 sets of receiving tubes to run a receiver for a few years is dead wrong. Tubes in the old 5 tybe series filament BCB radios with the plastic knobes and live chassis took a beating every time they were turned on but STILL lasted many years. A most intersting setup was an oscilator tube in the Hallicrafters SX 101 which was on ALL THE TIME the unit was plugged in, on its own little filament transformer. After TWENTY YEARS or so the emission was down far enough to require replacement. Spare me the "you'll need tens sets of tubes" line. People who say that have likely have neve owned a tube set.
 
Convert Tube Receivers to Solid State  
by K1DA on June 29, 2013 Mail this to a friend!
If you really want to know how long tubes can last, Google "transalantic telephone cable" and see how long the repeater amp tubes in those systems were designed to last.
 
Convert Tube Receivers to Solid State  
by K6CRC on June 29, 2013 Mail this to a friend!
Admittedly a small data set, but I have purchase and sold many Hammarlund RXs over the past 15 years. Many of the small signal tubes were original Hammarlunds. I have a calibrated tube tester, and I think I may have found 2 or 3 weak/bad tubes in all of the receivers. More likely to find leaking electrolytics or cracked power resistors.

Even in old audio equipment that I have restored, the power amp outputs are the only thing that seems to go bad. Of course, most of the tubes were Telefunken or Amperex, and were very high quality. Luckily, nearly all output tubes are still in production. Rockers like their tube amps.

If I had a tube RX, I would probably get a spare for each tube, maybe an extra rectifier. That would probably last the life of the radio (and me also)
 
Convert Tube Receivers to Solid State  
by ONAIR on June 30, 2013 Mail this to a friend!
Kinda like putting an electric motor into a '69 Camaro, but I'll try it!
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on June 30, 2013 Mail this to a friend!
Yes, 'ten' sets of replacement tubes is a real stretch--but I don't remember anyone specifying that many on this thread. Someone is playing around on that one.

It's always a good idea, however, to have a single set of tubes on hand, and maybe two--possibly three--of the tubes that were known to be failure prone in a set. That is just good common sense. Then there are those people these days that don't have any common sense in the first place!
 
RE: Convert Tube Receivers to Solid State  
by K1DA on June 30, 2013 Mail this to a friend!
Anyone who has done worked with the Drake R4C and the entensive list of modifications which keep it well up the list of good receivers today knows that the SOLID STATE third mixer in the first batch was converted BACK to a tube by Drake in the later series. So my context is Not "golly, I made a tube rceiver solid state -- look at ME I'm soooo advanced" it's that I want a GOOD reciever. One might wish to review W8JI's comments on the 4C and look at the rankings.
 
Convert Tube Receivers to Solid State  
by W6WRT on June 30, 2013 Mail this to a friend!
Please DO NOT butcher these wonderful old receivers! All you will end up with is a worthless piece of junk instead of a valuable piece of ham radio history. If you want a solid state receiver, please BUY ONE!!

73, Bill W6WRT
 
Convert Tube Receivers to Solid State  
by K1DA on June 30, 2013 Mail this to a friend!
Another prompt replacement in the R4C was to the amazingly BAD, factory, solid state (there's those words again) AUDIO stage, which got dumped for an LM 380 series, once they became available. The 4C never sounded as good as the earlier R4, R4A (two versions) and R4 B.
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on July 1, 2013 Mail this to a friend!
None of the tube receivers can compete with the new solid state receivers today. They are OK if you want to be all nostalgic, but they are not fun to live with on the bands. Some of the designs were horrible junk when they were new, let alone how bad they have degraded over 50+ years. If it is YOUR radio, you are entitled to do what you want with it. Next we will have you libratards declaring these radios as national treasures and regulating what restorations can and cannot be done on them!
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on July 1, 2013 Mail this to a friend!
W6WRT.....

This is such a ridiculous non-issue issue. Jumping on a topic with such intensity and emotion over something that's hardly even occurring is nuts. You're making it appear that national treasures, otherwise destined for the Smithsonian, are being butchered everywhere without mercy. Some of the things you guys get excited about....good grief. You're alive, you're free (for now), you're comfortable, and live better than probably 90% of the human race. If you can't help it, get excited about something tangible and real.
 
RE: Convert Tube Receivers to Solid State  
by AE6RO on July 1, 2013 Mail this to a friend!
I'm surprised that no-one brought up the EMP issue.
Tube radios are supposed to withstand EMP much better than the oh-so-delicate solid state radios of today.

You'd have to be an electrical engineer to make a successful conversion and what you'd wind up with is the whole being less than the sum (cost) of the parts. Why bother?

Believe it or not, there are some tubes in current production. Thanks to musicians and tube audiophiles many tube-type parts are out there. John
 
RE: Convert Tube Receivers to Solid State  
by G3RZP on July 2, 2013 Mail this to a friend!
I wonder whether at the end of the day, the performance is really adequate for serious use on the bands? Many of these old receivers really weren't very good on the higher bands - poor image rejection, for example. Fitting FETs won't cure that. Also, most FETS don't have the mutual conductance of things like a frame grid pentode, while a cascode is really needed to get the stability. Bipolars will give impedance matching problems, both input and output.

All in all, it seems that to do it well needs lab full of test gear and a lot of work, and if not done well, is a lot of work for nothing.

 
RE: Convert Tube Receivers to Solid State  
by K1CJS on July 2, 2013 Mail this to a friend!
Electrical engineer? You mean electronic engineer, don't you?

In any event, I've seen some hobbiests who could run rings around some of those so called electronics engineers. It's just more proof that that sheepskin on the wall means little--except that in most cases the person whose name is on it could pay the almost absurd sums of money needed to get it!
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on July 2, 2013 Mail this to a friend!
@K1CJS
Sheepskin doesn't cost a thing when Uncle Sam pays for it via the GI Bill. What branch of the military did you serve in?
 
RE: Convert Tube Receivers to Solid State  
by PA0LPS on July 2, 2013 Mail this to a friend!
Shouldn't we have had this discussion about 40 years ago?
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on July 2, 2013 Mail this to a friend!
"Electrical" Engineering.....

http://www.admissions.purdue.edu/majors/majors_details.php?MjrCd=ELECENG

Hoping this works out for my son. We'll know by the application deadline in the fall.
 
RE: Convert Tube Receivers to Solid State  
by G3RZP on July 2, 2013 Mail this to a friend!
My only sheepskin is Senior Member IEEE - for which you have to be proposed by three Senior members.

I have had 16 successful patent applications, although all but one have lapsed.
 
RE: Convert Tube Receivers to Solid State  
by G3RZP on July 2, 2013 Mail this to a friend!
My only sheepskin is Senior Member IEEE - for which you have to be proposed by three Senior members.

I have had 16 successful patent applications, although all but one have lapsed.
 
RE: Convert Tube Receivers to Solid State  
by G3RZP on July 2, 2013 Mail this to a friend!
My only sheepskin is Senior Member IEEE - for which you have to be proposed by three Senior members.

I have had 16 successful patent applications, although all but one have lapsed.

I'm far more proud of the WAZ and DXCC Honor Roll!
 
RE: Convert Tube Receivers to Solid State  
by AE6RO on July 3, 2013 Mail this to a friend!
I'd really like to see a modern software or "electronic" engineer successfully convert a tube receiver to solid state. Tip: The cold end of the soldering iron is what you hold on to. I don't think that computer-aided design will help. Better take off your tie first. John
 
RE: Convert Tube Receivers to Solid State  
by KD2BD on July 3, 2013 Mail this to a friend!
I converted my HQ-140-X to a solid state design 25 years ago and have never regretted it. The receiver features better sensitivity, better stability, and operates on less power than that required to light the filament of the original 6V6 audio output tube alone. It also has a real product detector now, and the AGC operates with the BFO turned on, which are features not possible with the original design.

JFETs were used to replace the 6C4 local oscillator and the half of the 12AU7 that served as the BFO. The 6BE6 mixer was replaced with an LM1496 doubly balanced mixer. The RF and every IF stage was replaced by 40673 dual gate MOSFETS, with AGC voltage applied to the second gate of each MOSFET. The whole thing operates on 12 volts, including the dial lights.

While I also maintain and restore tube equipment, I have no qualms performing these types of conversions, especially when I intend to keep the receiver for life. There are times when burning 5 volts at 3 amps to light a 5U4, and employing hundreds of B+ volts to amplify microvolt and millivolt-level RF and IF signals simply are not justified.

Incidentally, the reason the solid-state audio output stage in the Drake R4C is so "BAD" (as K1DA pointed out) is not because it is solid state, but because it ran Class A with so much quiescent DC collector current that the core of the output transformer became saturated.

Same deal with the Drake 2C, so there weren't any lessons learned there.


73, de John, KD2BD
 
RE: Convert Tube Receivers to Solid State  
by KV4JT on July 3, 2013 Mail this to a friend!
Thank you, thank you, thank you John, KD2BD. I am the author of the article. My plan was to duplicate each stage with a solid state equivalent. I was forced to use dual gates as mixers and I selected MPF-102 FET's elsewhere because they are popular, cheap and they work. I use an audio board purchased on E-Bay. My question to you is how did you handle your audio amp?? I thank you for backing me up on the idea. I suspect other hams have tried it and been successful but we have never heard from them. I have CAD drawings which I will release soon. Do you have any drawings that show your work? By the way the only real secret to a successful conversion is in the way the FET is coupled (de-coupled) to the IF coils. It only requires a resistor, choke and capacitor and it allows you to use all the original IF transformers and coils. How did you do it?

Thanks again,
Charles, KV4JT
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on July 4, 2013 Mail this to a friend!
>>>>By AE6RO on July 3, 2013 I'd really like to see a modern software or "electronic" engineer successfully convert a tube receiver to solid state. Tip: The cold end of the soldering iron is what you hold on to. I don't think that computer-aided design will help. Better take off your tie first. John<<<<

Well, to write such a thing, it's obvious that you have no idea what a current Electrical Engineering college curriculum looks like. They're graduating some of the brightest, most capable young people ever. Many are hyper-motivated, and are working in some very high-level technologies in research and industry. To suggest what you've written shows your ignorance and is totally bogus.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on July 4, 2013 Mail this to a friend!
G3RZP, Thank you for proving my point! You don't need the sheepskin to be able to do successful work in the field--but some employers still insist on your having it.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on July 4, 2013 Mail this to a friend!
JohnZ, What does that have to do with anything? If you served in the military, you paid for your education--why do you think the GI bill was established, anyway? To repay the serviceman for their contributions and their service, that's why.
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on July 4, 2013 Mail this to a friend!
You did not answer the question as to what branch of the military you served in? You state that one has first paid and then is repaid by virtue of military service. What kind of money are we talking here? I can find nothing in the GI Bill that even alludes to a Ponzi-type scheme of pay and repay. In your initial rant, you state that a "sheepskin" can only be obtained by someone who is willing to pay large sums of money (your words). Now you are saying that the GI Bill is some sort of Pay-and-Repay scheme. You never mentioned anything about a repay in your original remarks. Which is it?
 
RE: Convert Tube Receivers to Solid State  
by AE6RO on July 4, 2013 Mail this to a friend!
K9MHZ: You are absolutely right. I have no idea what a current Electronic Engineering curriculum looks like. Last time I checked our local engineering school the only Hispanic names on the Directory were for the Janitorial staff. However, I would expect the current curriculum to be heavy on software design and light on hardware design and implemention. I'm afraid most electronics are manufactured offshore nowadays.

I would advise anyone studying electrical engineering now to remember the slogan, "It's not what you know, it's who you know." Perhaps this explains America's preeminence in electronics today.

But getting back to radios, the input/output impedances are different between vacuum tubes and solid-state. I would expect such conversion would have poor dynamic range and lots of intermod and crosstalk problems compared to the original tube design.

I did convert a Heathkit VF-1 to solid state when I was a Novice. It worked well. But I wouldn't do that nowadays to a tube receiver. Cheers, AE6RO John

P.S. Don't be hatin'!
 
RE: Convert Tube Receivers to Solid State  
by KD2BD on July 4, 2013 Mail this to a friend!
Charles,

I used an LM-380 audio chip in my solid-state conversion.

The conversion was so simple that I never documented the process. (And I've never had to make any subsequent repairs, either.)

Once I found that I could make the local oscillator work and track properly with a JFET soldered underneath the 6C4 socket with a 12 volt external power supply, I figured the rest would be easy.

And for the most part, it was.

For the RF and IF amplifiers, I basically tied the Drain of each 40673 MOSFET to the previous 6BA6 Plate connection, G1 to Grid, and Source to ground through a red LED and a parallel RF bypass capacitor.

The LED serves two purposes. It lights up so I can say my receiver glows in the dark (and therefore is "real"), and more importantly, it establishes a 2 volt fixed bias on the Source. This bias is needed to drive the MOSFET to cutoff when G2 is brought down to zero volts through AGC and manual RF gain control action. I think I put about 1000 or so ohms of resistance from +12 volts to each source to keep each LED conducting, regardless of actual Source current, which varies with AGC action.

So, Vdd for each MOSFET is fed through each IF transformer winding, just like Plate voltage was for each 6BA6 in the receiver's original design.

I think making plug-in modules for tube replacements would be difficult. Tubesters and Fetrons were attempts at doing this in the past, and only enjoyed limited success for a variety of reasons.

Sometimes it's better just to re-design a specific circuit based on the general needs of the circuit, not so much the specifics of the active devices originally used. For example, I would be more inclined to design an audio amplifier using an op-amp or two, configured for the impedances and voltage gain required, rather than try to design the solid state equivalent of a 12AX7 that I wish to replace.

AE6RO wrote:

> But getting back to radios, the input/output
> impedances are different between vacuum tubes and
> solid-state. I would expect such conversion would
> have poor dynamic range and lots of intermod and
> crosstalk problems compared to the original tube
> design.

Not so.

MOSFET input impedances are at least as high, and may even be higher, than those of small signal triodes and pentodes of the type used in HF receivers.

I have not had ANY crosstalk, dynamic range, or intermodulation distortion issues after doing my solid state conversion.

(I did initially when I used a 40673 MOSFET (6BE6 substitute) as a mixer, but those issues vanished after I replaced the 40673 with an LM1496 doubly balanced mixer IC.)

So, there! :-)


73, de John, KD2BD
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on July 5, 2013 Mail this to a friend!
JohnZ, My RANT? You just went off the deep end. The same as what branch of the service I was in. NYOB, just as it's none of mine what branch YOU served in. For purposes of this discussion, it doesn't matter. As far as pay/repay, it's obvious. Military volunteers serve our country and are repaid by things such as the GI Bill, commissary privileges, Veterans medical plans etc.

You're just another unidentifiable guy that likes stirring the pot, aren't you? Well, you can do as you please, I'm just not going to bother with your bullsh** anymore.
 
RE: Convert Tube Receivers to Solid State  
by AE6RO on July 5, 2013 Mail this to a friend!
Well I was half-right, anyway. Not everyone would know how to install an MC-1496 product detector in place of the previous tube diode detector. So they could get into trouble performing the conversion. By the way, isn't "source" supposed to be connected to Vdd? and "drain" connected to ground?

I just think tubes are more fun. I remember an article in a 1980s "ham radio" magazine about converting tube receivers to solid state, and another one in "73". But, nowadays many musicians, audiophiles and AMers prefer the warmer sound of tubes so some tubes such as 12AX7 and 12AU7 are in current production today. Other common types are available NOS. ;> 73, John

73, John
 
RE: Convert Tube Receivers to Solid State  
by SWL2002 on July 5, 2013 Mail this to a friend!
"By the way, isn't "source" supposed to be connected to Vdd? and "drain" connected to ground? "

Hmm, it is just sometimes better to shut up than continue speak and show us that you HAVE NO CLUE!
 
RE: Convert Tube Receivers to Solid State  
by JOHNZ on July 5, 2013 Mail this to a friend!
@K1CJS
Sadly, you have resorted to name calling. As a result, that is the end of any adult discussion. In reply to your curiosity, your branch of military service, if any, is relevant to our discussion, since you made the statement only people with huge sums of money can pay for a sheepskin. By using the GI Bill, I paid no money for a sheepskin. Incidentally, you are erroneously calling all who served in military "volunteers." That is not correct. Prior to the all volunteer military, the United States of American had an involuntary military draft. You never did say what branch of the military you served in? Had you done so, I would have been able to describe your options for not having to pay for a sheepskin. In addition to the GI Bill, active duty service members can also receive college tuition assistance, as well as command assistance for earning a sheepskin (college degree). Moreover, this leaves their GI Bill available for use after active military service. Despite having left active duty years ago, you may still very well qualify for veteran educational benefits? Good luck with your future educational endeavors, if you have any. If you keep the author separate from the topic being discussed, one can learn much in these forums. Unfortunately, that is a skill not often seen, which is why many of these discussion topics deteriorate into personal attacks and name calling. Well, again, best of luck in your educational endeavors, and don't hesitate to ask, should you have any questions I can answer for you in the future. 73, JohnZ
 
RE: Convert Tube Receivers to Solid State  
by KX4OM on July 5, 2013 Mail this to a friend!
I had been interested in doing something like this for 20 years or so. Finally last year I converted a Heathkit IG-102 sig gen to FETs using 2N5486 devices. I wired an LED to the former indicating lamp socket. I ran tests on the sig gen for about 3 weeks, tweaking the bias values to try to get good performance. I took probably 200 screen shots of scope outputs from my Velleman PCS-500 scope.

Generally, the performance was similar to the original tube configuration except for the highest frequency range; it suffered from parasitic oscillations starting at about 40 MHz. One problem that showed up was a slightly flattened sine wave at the FET output transistor, and changing the biasing of that stage many times wouldn't cure it. The signals from the oscillator looked good on the scope (50MHz limit on the scope, 25 MHz limit on its spectrum analyzer functions.)

Except for the highest range,sweeping across the ranges with a log power meter at 50 ohms generated about the same levels before the modification. By the way, I powered the modified sig gen from a 9 volt battery mounted on a clip on the top of the chassis.

I ended the experiments, wrote up the compliation of the data and my findings, and I un-modified the unit back to the condition it was in when I previously had enhanced it 3 years ago: a 3-prong wire AC plug with grounded chassis, with a fuse in series with the power switch in the hot line of the AC cord. I replaced the 2 capacitors used as line filters with Y2 line rated safety caps.

I suppose that those safety mods would upset some serious purists, but the IG-102 as well as many other units where function can be improved with minimal change in form is OK by me. It might upset others that I'm also deconstructing 2 non-functioning Tempo 2020 late '70s hybrid transceivers to preserve the operating status of my working 2020 along with those of a few friends. I don't think that 2 scrapped relics of that somewhat uncommon rig or my other modified equipment will shock and dismay electronics archeologists 50 years from now.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on July 5, 2013 Mail this to a friend!
>>>>by AE6RO on July 4, 2013 ....I have no idea what a current Electronic Engineering curriculum looks like. Last time I checked our local engineering school the only Hispanic names on the Directory were for the Janitorial staff.....<<<<


I have absolutely no idea what that is supposed to mean. You have really taken this thread in an odd direction.
 
Convert Tube Receivers to Solid State  
by KE5ICG on July 6, 2013 Mail this to a friend!
K4VRP may be on to something here. As he has observed, lots of old radios have little or no true collector value. Should all of those be scrapped? Maybe not. I'll be interested to see what he comes up with going forward.

Press on K4VRP, and please keep the group posted.

73 -- Ray, KE5ICG
 
RE: Convert Tube Receivers to Solid State  
by AE6RO on July 6, 2013 Mail this to a friend!
To SWL2002: Sounds like you are one of those old "Popular Electronics" SWL callsigns. And, I do SO have a clue. The drain and source can be hooked up interchangeably, depending on the circuit. Nevertheless, tubes are better.

K9MHZ: Surely you understood what "it's not what you know it's who you know" means. Sadly this also applies to engineering, especially nowadays. John
 
RE: Convert Tube Receivers to Solid State  
by KV4JT on July 6, 2013 Mail this to a friend!
To KD2BD, Yes you can connect a FET drain directly to an IF transformer made for tubes but the coil will not peak properly. It will be very broad. To peak properly I decouple the circuit by doing this: I connect the drain through a resistor (usually 2200 ohms) and a small 2.5mh choke in series. The choke will satisfy the impedance requirement of the FET. Then I connect a small cap (sometimes as low as 15pf) between the drain and the IF coil. This will satisfy the high impedance requirement of the IF transformer and it will peak sharply. The values must be adjusted to the circuit. This arrangement will work in almost all circumstances. The source resistor and cap should be selected to satisfy each circuit requirement. The gate is inherently very high impedence and must be coupled to an IF coil with a small capacitor. A resistor in the order of 1 to 10 meg is enough to stabilize the gate. This circuit is the secret to making a conversion successful. The power supply works best between 21 and 24 volts in this arrangement. The RF circuit can be very tricky. The mixers almost always require a dual gate device. Sometimes direct mixing will work OK. There are other tricks to a conversion but it is all very straight forward, inexpensive and easy to do. When I publish my papers I will provide a complete explanation of all of it. Everyone will benefit greatly from it if they wish to attempt a conversion. I guarantee it will work. The tricks I have found will aid in converting almost any tube radio. I have not found one yet that could not be converted. Replacement modules could be made to work in many cases but I don't think it will ever cover 100pct of all circumstances without doing some under-chassis work.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on July 7, 2013 Mail this to a friend!
JohnZ, First you called my statement a rant, and now you say I'm namecalling. FWIW, you don't seem to know what you're talking about, since I did neither.

About one thing you're right--it is the end of any adult discussion. It's obvious you're not an adult. BTW, NOW I'm namecalling--in a general sense.
 
RE: Convert Tube Receivers to Solid State  
by K1CJS on July 7, 2013 Mail this to a friend!
Oh, dear, I have to apologize. I was wrong in that last statement since you can be an adult--and still act like a child that has no idea of the meaning of the words you use or the way concepts relate to each other. I'm sorry.
 
RE: Convert Tube Receivers to Solid State  
by KD2BD on July 7, 2013 Mail this to a friend!
Charles,

The decoupling method you described might be required when using single JFETs in place of pentodes, since the output impedance of JFETs is low at low Vdd potentials.

Based on the component values you used and the frequencies involved, it almost sounds as though the JFET is now looking into a series, rather than parallel, resonant circuit. (Not that there's anything wrong with that, BTW.)

I did not experience this issue when using 40673s.

The RCA 40673s have become obsolete, by the way, but I'm sure there are more modern devices available as replacements. In a pinch, a cascode arrangement of JFETs might serve as a good well, and I've read a number of articles that suggested using a cascode arrangements of JFETs as a replacement for a pentode.

As far as the "tube sound" being "superior" to that of solid state devices, the following article suggests the difference in sound is more a result of the circuit topology (transformers, damping factors, impedance levels, parasitic capacitances, etc.) than the performance of the active devices used:

http://electronicdesign.com/analog/tubes-versus-solid-state-audio-amps-last-word-or-house-fire-part-2

Seems they were able to create solid-state equivalents for tubes in some audio amplifiers, and the difference between the two was only a fraction of a dB!

And, yes, 12AX7s are still available today, but are terribly overpriced due to the hyped-up demand created by audiophiles.

Imagine the electric bill generated by running this tube-based digital clock:

http://www.jogis-roehrenbude.de/Leserbriefe/Bruegmann-Digital-Roehren-Clock/Digital-Roehrenuhr.htm

Yikes!

73, de John, KD2BD
 
Make tube radio parts available...  
by WB4LCN on July 8, 2013 Mail this to a friend!
If you are converting tube rigs to SS, maybe make available the parts that are removed for those who need the parts to keep their tube rigs alive.

dave :)
 
RE: Make tube radio parts available...  
by 9V1VV on July 8, 2013 Mail this to a friend!
I converted a Marconi Elettra marine receiver to MOSFET many years ago using 40673 mainly for the RF and IF stages. Other stages were normal bipolar. It worked fine, but the Elettra was a conventional single superhet. I would love to convert the RA17 (I have three of them and would keep two in their original state). The Wadley design makes it tricky to do - impedance matching is a headache. The best available MOSFETs available now are BF964A's - dual gate for AGC on the second gate.
It is actually easier to completely overhaul these receivers with new caps and resistors and wiring looms than convert to solid state however.
 
RE: Convert Tube Receivers to Solid State  
by KB6YH on July 9, 2013 Mail this to a friend!
Bill, you are 100% right. I've been into radios since 1950.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on July 9, 2013 Mail this to a friend!
>>>>by KV4JT on July 6, 2013....Replacement modules could be made to work in many cases but I don't think it will ever cover 100pct of all circumstances without doing some under-chassis work....<<<<

Yeah it's been quite a while, but I do remember a ma 'n pa company that made those and sold them in QST and 73. I think it was right around the time of hybrids (eg. TS-520S, etc), and people were interested in going solid state with their older rigs, while leaving the 12BY7 driver and 6146 PAs in place, just like the new Kenwoods at the time. I'm thinking it was short-lived, probably because of what you noted above.

Best,

Brad, K9MHZ

 
RE: Convert Tube Receivers to Solid State  
by WA7KGX on July 20, 2013 Mail this to a friend!
I did a Google search on "frame grid pentodes" and found fascinating information. Some Tektronix equipment used some of these tubes. The cost of replacing these tubes as they went flat inspired solid state conversions. But did radios by Hallicrafters, National et al. use frame grid tubes?

I currently have two tube type radio receivers.
A 1936 Stromberg-Carlson 12 tube radio uses 6K7 metal tube pentodes. A Hallicrafters S-76 uses a 6CB6 RF amp with 8000 umhos transconductance.

My first project for the S-C is to replace an audio transformer with a long-tailed phase inverter to correct the poor bass.

My first project for the S-76 is to correct audio distortion that seems to go away after it warms up.

The second project is to add a product detector to the S-76. This could be a pair of FETs or transistors.


 
RE: Convert Tube Receivers to Solid State  
by KJ4IOR on July 29, 2013 Mail this to a friend!
"To me this is a bit like putting a string bikini on Grandma. Some things you should not do."

But if Grandma looks like Raquel Welsh or Sophia Loren, I say go for it!! :-P
 
RE: Convert Tube Receivers to Solid State  
by N1DVJ on August 5, 2013 Mail this to a friend!
Years ago RCA used to offer solid state equivilents for a number of tubes. These were true workalikes in that they even loaded the filament connections fairly close to what the glass tube did. With that in mind, what's the point.

However it was a neat idea. By taking it a little bit further, it could make a neat way to save an old radio. Make up small modules that emulate tubes, but don't worry about the filiments. For filiments, either redo all the tubes on that leg to solid state and not connect at all, or put in a single ballast for whatever you had to take out of the loop. Sure, it might take a little bit of rewire/hacking to do it right, but in the end you'll have a workalike radio that still maintains the 'flavor' of the original.

If that glow is all important to you, put in a few yellow and red LEDs hidden in the chassis so you can see the glow though the slots.
 
RE: Convert Tube Receivers to Solid State  
by K9MHZ on August 10, 2013 Mail this to a friend!
Kind of like a microwave in a cave, but it's all OK.
 
Convert Tube Receivers to Solid State  
by VE3CUI on August 10, 2013 Mail this to a friend!
Do what you will, the choice is certainly yours, but personally I would NEVER convert a tube-type rig to solid state at all here...

It's like acquiring a stock, original 1925 Model T Ford, then dropping a Chevy 350 V-8 into it, replacing the drive train, & adding "trick" mag wheels. To some, the result is a beautiful 1925 Model T Ford hot rod---but to me, is ghastly!

To each, his own, I s'pose...!
 
Convert Tube Receivers to Solid State  
by VE3CUI on August 10, 2013 Mail this to a friend!
Do what you will, the choice is certainly yours, but personally I would NEVER convert a tube-type rig to solid state at all here...

It's like acquiring a stock, original 1925 Model T Ford, then dropping a Chevy 350 V-8 into it, replacing the drive train, & adding "trick" mag wheels. To some, the result is a beautiful 1925 Model T Ford hot rod---but to me, it's ghastly! Keep it stock, & original, as much as possible.

To each, his own, I s'pose...!
 
RE: Convert Tube Receivers to Solid State  
by WB6DGN on August 11, 2013 Mail this to a friend!
"Jack KZ5A: What someone does with HIS OWN radio is NONE of your business."

And, conversely, his legitimate OPINION, is none of YOUR business. This, after all, is a DISCUSSION BOARD where people share diverging opinions. THAT'S WHAT ITS FOR! If you don't agree, that's fine, state your alternative ideas but DON'T attack him for his. Nobody wants to hear your personal attacks.
Tom
 
RE: Convert Tube Receivers to Solid State  
by WB6DGN on August 11, 2013 Mail this to a friend!
"Would those saying "it can't be done" kindly step out of the way of THOSE DOING IT!"
Tom
 
RE: Convert Tube Receivers to Solid State  
by K4KYV on August 13, 2013 Mail this to a friend!
I wouldn't recommend a wholesale conversion of the entire receiver. A worthwhile improvement might be to convert the high frequency oscillator and BFO to a FET and let them run all the time with a small auxiliary power supply, eliminating the warm-up drift.

I wouldn't mind tearing into a piece-of-junk set (that's what a lot of the ones made in the 50s and 60s were, from the outset). But a nice classic piece like a Collins 75A-4 is a different matter. I might make a modification to one of those to improve performance, like converting the PTO to solid state, but I always make sure any mod to a set like that is completely reversible. I cringe when see a fine set, like the otherwise mint-condition 1935 HRO I picked up years ago at a hamfest, that had a couple of 3/8" holes blasted in the front panel to accommodate some Hammy Hambone modification that didn't even work.

Don k4kyv
 
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