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Author Topic: Tube Amp "Component" Kit  (Read 17224 times)
K7PEH
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« on: February 22, 2013, 10:21:46 AM »

Has anyone created (recently and still available) a tube amp component kit?  What I mean by this would be an amplifier kit using a standard available tube capable of about 1000 watts or more to legal limit plus.

By component, I mean a kit that specifies and provides printed circuit boards for particular area such as power supply, rectifier and filters, and maybe components (or, sources) for pi-network inductors and capacitors.

Close, but not quite to the level I am asking about, might be some of the amp designs in the ARRL HB.  Although I understand the problems and cautions of providing a complete, high-voltage, tube amp kit, something that outlines details and provides components or good sources is more of what I am looking for.

So, I am familiar with everything available in the last 10 years of the ARRL HB but I am looking for something that may be more than the typical HB article.

When I was in high-school (circa 1964/1965) I built a dual-811 linear amplifier from the circuits available in the HB back then.  It worked fine with the slight problem that harmonic suppression was not as good as it should have been by today's standards.  I just might want to build another tube linear amp before all the key components (power transformer, tubes) are lost to antiquity.

Thanks.

73, phil, K7PEH
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KD0REQ
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Posts: 839




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« Reply #1 on: February 22, 2013, 10:26:21 AM »

this has been asked before.  consensus is that with the FCC spectrum purity regs required of manufacturers, nobody would touch this with a ten-meter pole (heh, heh.)

you might build it well.  but Splatterin' Sam Slipshod down the block, well, a propane torch and hammer are not the tools of choice to maintain good RF and ground paths inside.
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N8CBX
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« Reply #2 on: February 22, 2013, 11:29:34 AM »

You say this has been asked (and discussed, I guess) before, and I would like to review those discussions if I can find them, but I don't think the FCC as any rulings against electronic "kits" manufacturers, do they?
Jan N8CBX
« Last Edit: February 22, 2013, 11:32:03 AM by N8CBX » Logged

Dayton Ohio - The Birthplace of Aviation
N3QE
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Posts: 2029




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« Reply #3 on: February 22, 2013, 12:14:39 PM »

I think everything that would go in such a kit, can be ordered as a part or assembly or PC board from Ameritron or other vendors right now.

As a practical matter, buying new parts from the catalog is a very expensive way to get most of an amp. Many folks do it more economically by taking a junker amp or two (aka "project amps") from hamfests and re-using parts/chassis to make a new amp. Some of these projects center around past homebrew attempts, others center around modding an amp to handle a band it was never built to handle, and some bear little to no resemblance to the original amp just re-using some parts.
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K6AER
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« Reply #4 on: February 22, 2013, 12:55:39 PM »

A - The FCC would have to have the kit mostly assembled for the type acceptance to be issued like the KPA-500.

B - The company lawyers would never let it out of the building for liability issues with High Voltage.

C - The kit would cost more than an assembled unit.
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K7PEH
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« Reply #5 on: February 22, 2013, 03:04:21 PM »

OK, I think my question might have been misunderstood.

I am not looking for some commercial product, that is a kit product such as Heathkit used to provide.  But, rather, I am wondering if anyone has provided some of the harder to DIY components for such a home-brew amplifier.

Example -- for a number of the projects listed in ARRL HB there are PCBs available at a reasonable cost.  In fact, such kits are nothing other than a schematic, a parts list (of major parts), and some textual description of details for the kit.  What I am wondering is the next level up.  I do not expect, nor would I want is a kit that is a box with all the parts, all the cabinet pieces, and so on.

Another example, more of what I am looking for, is the offerings of the Communication Concepts web site for solid-state amplifiers.  They offer circuit descriptions, heatsinks, combiners/splitters, and so on as individual components useful in building one of their amplifier designs.  I am looking for the same kind of thing (maybe) for tube based amplifiers.  Maybe it does not exist, too bad if it doesn't.

73, phil, K7PEH
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QRP4U2
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« Reply #6 on: February 22, 2013, 03:19:31 PM »

Not that I am aware of.

Now, what you can do is go to some of the earlier ARRL publications, such as QEX or their Amplifiers publications, 73's Magazine, or the Internet, and build your own Amp from collected parts.

You can find parts and tubes from AES

http://www.tubesandmore.com/ and http://www.esrcvacuumtubes.com/ and

http://www.rfparts.com/ or MFJ or by attending Hamfests, especially parusing the tailgaters.

As far as PCB's,  FAR Circuits  http://www.farcircuits.net/  has a lot circuit boards for various projects.

And oh yes, go to he Homebrew and Boatanchor sections of various ham related web sites such as
http://www.eham.net/ehamforum/smf/index.php/board,16.0.html and

http://forums.qrz.com/forumdisplay.php?32-Homebrew-and-Kit-Projects


Phil - AC0OB

« Last Edit: February 22, 2013, 03:45:51 PM by QRP4U2 » Logged
K8AXW
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Posts: 3602




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« Reply #7 on: February 22, 2013, 08:32:27 PM »

Phil:  What you're asking would be nice.  Unfortunately, this no longer happens since Heath went out of business.  I understand you're not asking for a "kit" as in Heathkit but still, this just doesn't happen for the reasons already mentioned.

A good project for you would be to source ALL of the parts necessary to build a linear that you have selected from the HB or other source.  I'm sure this will be an eye opener, with the final cost being as high if not higher than an assembled commercial amplifier.

I build a 1400w 2 X 3-500Z amp from the HB several years ago.  My total cost for this amp was $600.

This didn't include the Eimac aluminum air sockets, chimneys, commercial tank circuit,HV power transformer, a never used $600 Bud computer cabinet and a few other smaller components which were given to me by other hams or my place of employment.

This final cost did include some niceties like two vacuum variables, 3 wide-view Triplett meters, B&W turns counters and a few other things not found on the usual homebrew amplifier.

It took 5 years to accumulate enough parts to build this amp, which is always a factor in homebrewing an amp.  I'm talking about a lot of hamfest walking and haggling!

Yea Phil, it would have been nice to have access to a kit of parts, or even a partial kit but such will never be the case.

This isn't to discourage you or anyone else from building an amp but simply to point out what is involved.  The personal satisfaction of building something like this and bringing it to life is an awesome experience.  If you enjoy building, I recommend an amp.  Just be aware of what is involved.
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N3QE
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« Reply #8 on: February 23, 2013, 05:46:30 AM »

They offer circuit descriptions, heatsinks, combiners/splitters, and so on as individual components useful in building one of their amplifier designs.  I am looking for the same kind of thing (maybe) for tube based amplifiers.  Maybe it does not exist, too bad if it doesn't.

The RF-specific parts are readily available from Ameritron/MFJ catalog new, and other sources too. Things like variable caps, sockets and chimneys, bandswitches, etc. They even have HV/filament transformers and already-assembled boards.

All the other parts are available from the major electronics and industrial distributors.

Buying all new parts, you will end up paying many more times than what a new amp costs. If a middleman made a kit out of these same new parts, you will end up paying even more!

I still strongly believe the "kit" you want, if you want to save money, is the junker/project amp on the table at the end of the hamfest.

Tim.
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N4OI
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« Reply #9 on: February 23, 2013, 06:42:06 AM »

Ameritron offers several amp kits -- they happen to be assembled, but you will still enjoy the "building experience" while you work out the initial bugs.

73 ES GOD BLESS U ES URS DE KEN N4OI  Grin
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K7PEH
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« Reply #10 on: February 23, 2013, 07:42:09 AM »

Ameritron offers several amp kits -- they happen to be assembled, but you will still enjoy the "building experience" while you work out the initial bugs.

Ha!  I did that kit about 9 years ago.  The AL-572 worked great for about two days and then two tubes would not light up.  Opened it up and found a broken cold solder joint feeding the filament wiring for two of the tubes.  I sold the AL-572 about a year later.  Currently, my two amps are both solid-state.

A previous message mentioned hamfest junkers.  I have been keeping my eyes open for those.  Indeed, mostly because the idea of merely using the cabinet alone if nothing else survives would be useful.  I did see a junked old home-brew amplifier at a recent (just last week) hamfest here in the northwest.  No tube but guessing it might have been a 4-1000 amp.  Also, the power transformer was missing from the amp and the owner was asking way too much.

73, phil, K7PEH
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K8AXW
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« Reply #11 on: February 23, 2013, 08:46:55 AM »

Quote
I did see a junked old home-brew amplifier at a recent (just last week) hamfest here in the northwest.  No tube but guessing it might have been a 4-1000 amp.  Also, the power transformer was missing from the amp and the owner was asking way too much

This is the second part of this sad story Phil.  In recent years I've noticed the lack of usable linear components and what I have seen were priced out of sight.  I know there are hamfests where a lot of this stuff is still available but for the most part, I believe that hamfests are simply becoming places to dispose of junk, computer junk and Chinese tools.

I'm leaning toward what seems the only viable option (assuming you want to build) which is solid state and obtaining PCBs and some parts from companies like Communications Concepts.

Even with this, it will be necessary to do a lot of research on the Internet to find what pitfalls and problems others have encountered trying to get these amps to work properly.

While the finished product can be great, getting there is like walking through a cow pasture.  You need to watch every step!
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QRP4U2
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« Reply #12 on: February 25, 2013, 08:00:50 AM »

Quote
Also, the power transformer was missing from the amp and the owner was asking way too much.


This is where you make an offer 10 minutes before the close of the Hamfest.

Sometimes negotiations have to be done. If the seller doesn't acept your offer, you keep your money and he has to haul the stuff home.

Phil - AC0OB
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K8AXW
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« Reply #13 on: February 25, 2013, 10:22:47 AM »

Phil:  Right on!!  I usually try negotiating as soon as I see something I might want.  If I'm unsuccessful I move on but make a note of what and where.  Close to the end of the hamfest I beat feet back to the #1 item on my list and if it's still there start to work on the guy.  

If he's unrelenting on his price then I move on to the next item on my list and so forth.  Working hamfests is a learned art.... and it's also great fun.  The one thing to be remembered is to be pleasant, understanding and make a point not to insult the guy.  After all, it's HIS stuff and he's the one who puts a value on it.

Perhaps the greatest compliment I've ever received at a hamfest was once when I was selling.  I had a load of stuff to get rid of and I was hawking my wares to everyone that came by, but in a pleasant and lighthearted way.  It was surprising how most responded to this with amusing return banter or looking and buying something.  By the end of the day I had unloaded most of my junk.

In contrast the guy next to me had sold almost nothing.  As he was loading his stuff for the return trip home, he turned to me and said, "Do you mind if I ask you a question?"  I told him "No, go ahead."  

He then asked me in a very sarcastic tone, "Did you ever work in a carnaval?"
« Last Edit: February 25, 2013, 10:29:11 AM by K8AXW » Logged
K7PEH
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Posts: 1125




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« Reply #14 on: February 26, 2013, 05:12:08 PM »

This is where you make an offer 10 minutes before the close of the Hamfest.

Problem for me is that I am never around at the close of the hamfest.  I have never seen anything interesting to buy that I would spend the time to stick around for a cheaper price.  Typically hamfests start at about 9 AM but it is a very rare occasion for me to be around as late as 12 Noon let alone the afternoon hours.  Another problem is that when something does catch my interest, it is usually gone early.

73, phil, K7PEH
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