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eHam Forums => Amplifiers => Topic started by: W6JHB on December 27, 2012, 05:03:55 PM



Title: AL-811HD - Three Questions
Post by: W6JHB on December 27, 2012, 05:03:55 PM
I'm currently running an Elecraft K3/100 - had the matching KPA500 solid state amp, but sold it due to financial issues several months ago. Nice amp, but $2k is a lot of money for a 600-watt amp, in retrospect. Anyway, things have changed and I'm again looking at QRO operation. Not interested in spending a bazillion dollars, so after some research, I think I've set my sights on the Ameritron AL-811HD. I like the idea of having the 572B tubes instead of the 811A's.

I ran the KPA500 on the 117V line in the shack. It worked OK, but I'm pretty sure I I'd be better off getting a 220V line installed in the shack and run the AL-811HD from it, and not off the same circuit as the rest of the room. So, question one - how difficult is it (what is involved) to change the voltage setting on the AL-811HD? The specs say it is "user selectable for 100/110/120/210/220/230 VAC operation".

Question number two - 10/12 meter operation. I thought that I read somewhere on a review that this amp can be made to work on 10 and 12 meters simply be cutting a "green jumper wire". Is this true, or is there another "option" that needs to be purchased and installed?

Question three - there is a $70 inrush current protector offered - worth the money?

Thanks!


Title: RE: AL-811HD - Three Questions
Post by: N3JBH on December 27, 2012, 05:16:12 PM
My question #1 is why is the 572-B tube listed for the 811-Hd $10.00 less then  there regular 572-B tubes ? I want to know that answer first. I think i know the answer but i ask that question. Second It work fine on 120 volts on it's own circuit. #3 well i dont think spend the extra $70.00 on the surge gizmo.   Now my opinion if you replace only three of the tubes with 572-B tubes and leave the 4'th hole empty i think you find that the standard AL-811H amp will work quite well that way. In that case i see if they send you one with no tubes and just get 3 from RF Part's And have them knock off the price of the 4 tubes that belonged in it. Or just order it with the 4 811 tubes and then swap oy the tubes and you have spares.


Title: RE: AL-811HD - Three Questions
Post by: KH6AQ on December 27, 2012, 05:45:39 PM
The inrush current protector is not needed (at all).

Ameritron can tell you what the 10/12 meter mod is. It's supposed to be a secret.

The 811A tubes are likely more reliable than the 572B tubes in this amp. While the AL-811H uses four unreliable tubes the AL-811 uses only three. So, you can expect 25% less tube failures and an 811A is just $20. While the AL-811H runs higher power on SSB both amps will run 600 watts on CW (even though the manual for the AL-811 says 500 watts).

DX Engineering sells the AL-811 for $709. Note, you will need an RF wattmeter to tune up this amp.


Title: RE: AL-811HD - Three Questions
Post by: W8JX on December 27, 2012, 05:59:52 PM
For little more then the cost of a 811HD you can get a real amp, a AL80B. A soft start is a waste of money with this amp as it has a small transformer and uses same one as in 3 tube 811 amp. If you want 572 in a 811 amp get 3 tube version and retube it and you will ge as much output from it as a 4 tube one as the transformer is the limit with 572's in the amp, not 3 tubes. Also you might actually have shorter tube life with 4 572's as the transformer lacks power to load them properly to heat them enough to getter. Also on 10/12 meters just clip the wire.


Title: RE: AL-811HD - Three Questions
Post by: WB2EOD on December 27, 2012, 06:15:02 PM
In general, I agree the with the opinions already offered. 
You understand that the 572B's won't give you any more power out of an AL811(h) amp.  The limiting factor is the power supply. 

The 572B's therefore shift the "weak point" in this amplifier from tubes to the power supply. 
For example, when subjected to serious user errors, the 811 tubes may simply fail, they stop drawing current or blow the AC fuse and that is the end of it.  They cost about 20 dollars each and are quickly and easily replaced. 
The 572B subjected to similar conditions, may not fail and may draw enough current to damage the power supply.

Having said that, I believe the 811 and the 811H represent possibly the best "bang for the buck" in ham radio.   
Just follow the instructions carefully, tune quickly and WATCH THE GRID CURRENT.

Hope this helps
73
WB2EOD


Title: RE: AL-811HD - Three Questions
Post by: N3QE on December 27, 2012, 06:29:09 PM
Having said that, I believe the 811 and the 811H represent possibly the best "bang for the buck" in ham radio.   

It's astonishing, isn't it? A tube from 1939 was a bit of a sleeper (wasn't even the "RF tube" in the RCA lineup, it was the "AF" tube!) until the late 50's when the 30L1 came out, and today it hits the sweet spot even better in the highly optimized Ameritron amps.


Title: RE: AL-811HD - Three Questions
Post by: W8JX on December 27, 2012, 06:55:01 PM
Having said that, I believe the 811 and the 811H represent possibly the best "bang for the buck" in ham radio.   

It's astonishing, isn't it? A tube from 1939 was a bit of a sleeper (wasn't even the "RF tube" in the RCA lineup, it was the "AF" tube!) until the late 50's when the 30L1 came out, and today it hits the sweet spot even better in the highly optimized Ameritron amps.


Kinda a counter-diction here. More have trouble with AL811 amps be it tubes or parts than any other amp. Its a shame that no one made a modern SB 200 as even a 35+ year old one that hs been gone through is better amp than a new 811 which are over rated too.






Title: RE: AL-811HD - Three Questions
Post by: K7MH on December 27, 2012, 11:58:48 PM
I have a 1993 AL-811 and I am the third owner. The second owner, a friend of mine replaced the tubes as a couple were broken in shipping to him. I recently had to replace the power switch and that is the only problem I have had with it other although I still need to add some capacitance to the 80 meter padding capacitor. I did add the grid protection board when I replaced the switch.
I also recently added a 240V line to the shack which is a happy thing!! Switching the amp to 240V is very easy to do. Take a look in the manual which you can download.
I would however agree that the AL-80B is the best bang for buck amp out there. If I were going to replace the AL-811, I wouldn't hesitate to buy an AL-80B.


Title: RE: AL-811HD - Three Questions
Post by: KC4MOP on December 28, 2012, 03:37:35 AM
The AL80B looks better after each post. 1 very good forgiving tube the 3-500Z and 800 watts.
Looks like a lot of short comings with the modern versions of 572B amps from the past and audio tubes as RF tubes.

Fred


Title: RE: AL-811HD - Three Questions
Post by: W8JX on December 28, 2012, 04:44:24 AM
The AL80B looks better after each post. 1 very good forgiving tube the 3-500Z and 800 watts.
Looks like a lot of short comings with the modern versions of 572B amps from the past and audio tubes as RF tubes.

Fred

Nothing wrong with a 572 in a amp as long as it was designed for it and has a proper power supply. It can use considerably higher plate voltage and current to be fully exploited and non of which a 811 amp can supply.


Title: RE: AL-811HD - Three Questions
Post by: KH6AQ on December 28, 2012, 09:30:29 AM
W8JX is right. The AL-80B has one reliable tube vs. four unreliable tubes in the AL-811H.

But if I were low on funds I would go for the basic AL-811 and take my chances with the tubes. I had one and loved it. 


Title: RE: AL-811HD - Three Questions
Post by: KF7CG on December 28, 2012, 11:06:46 AM
I have a "regular" 811H amplifier and it works great for me. No problems over the two years I have owned it. Careful on tune up and don't push for the absolute maximum power out.

The 10/12 meter mod is a piece of cake when you find the green wire.

Often audio and seep tubes perform excellently at RF if their internal capacitances to not cause problems. The have to handle longer peak currents at audio, especially bass, than at RF. Ran the same pair of 6LQ6s in a TS511s for 8 years without problems and with a very clean signal too.

Some tubes don't like sloppy operators! Further, what is poison to one tube may not be to another and vice versa. By the way if you keep your duty cycle in mind 800 watts isn't that far out of line for the tubes.

KF7CG


Title: RE: AL-811HD - Three Questions
Post by: KE3WD on December 28, 2012, 11:46:49 AM
Literally thousands of Collins desktop amps using 4 811 tubes were in service for almost the entire life of the Strategic Air Command, not one of them had a soft start circuit in them.  They performed year in and year out, day in and day out, some of the ones I used back in the day were dented, scratched, beat up, repaired Lord knows how many times, and I have even witnessed them being used in lieu of tent pegs.  And then placed back into service. 

811A "Instant On" tubes -- with unbelievably low starting temps in places like Greenland, then the same amp might be moved to the tropics and used some more. 

Just sayin'...


73


Title: RE: AL-811HD - Three Questions
Post by: W9KDX on December 28, 2012, 12:02:26 PM
Literally thousands of Collins desktop amps using 4 811 tubes were in service for almost the entire life of the Strategic Air Command, not one of them had a soft start circuit in them.  They performed year in and year out, day in and day out, some of the ones I used back in the day were dented, scratched, beat up, repaired Lord knows how many times, and I have even witnessed them being used in lieu of tent pegs.  And then placed back into service. 

811A "Instant On" tubes -- with unbelievably low starting temps in places like Greenland, then the same amp might be moved to the tropics and used some more. 

Just sayin'...


73

Ah... but were those 811 tubes the current "Made in China" version?


Title: RE: AL-811HD - Three Questions
Post by: W8JX on December 28, 2012, 02:29:26 PM
Literally thousands of Collins desktop amps using 4 811 tubes were in service for almost the entire life of the Strategic Air Command, not one of them had a soft start circuit in them.  They performed year in and year out, day in and day out, some of the ones I used back in the day were dented, scratched, beat up, repaired Lord knows how many times, and I have even witnessed them being used in lieu of tent pegs.  And then placed back into service. 

811A "Instant On" tubes -- with unbelievably low starting temps in places like Greenland, then the same amp might be moved to the tropics and used some more. 

Just sayin'...


73

Ah... but were those 811 tubes the current "Made in China" version?


And the cost those amps new in todays dollars would be around 5 figures too. Not to mention very high quality too.


Title: RE: AL-811HD - Three Questions
Post by: KE3WD on December 28, 2012, 03:37:52 PM

Ah... but were those 811 tubes the current "Made in China" version?


And a Soft Start circuit is supposed to correct problems with badly manufactured tubes? 


73


Title: RE: AL-811HD - Three Questions
Post by: W6JHB on December 28, 2012, 07:14:33 PM
Guys - thanks for the many comments! After "discussions" with the XYL and reviewing the bank account, I took the low road and ordered a plain old AL-811 from DX Engineering. Yes, I'd love to have that AL-80B (or an Alpha for that matter), but household harmony wins out.  ;)

Oh yeah, had to get an RF watt meter to go behind the amp, so that just added more to the total. Arrghhhhh....!

Thanks again, 73 - Jim


Title: RE: AL-811HD - Three Questions
Post by: WB2WIK on December 28, 2012, 07:28:46 PM
Guys - thanks for the many comments! After "discussions" with the XYL and reviewing the bank account, I took the low road and ordered a plain old AL-811 from DX Engineering. Yes, I'd love to have that AL-80B (or an Alpha for that matter), but household harmony wins out.  ;)

Oh yeah, had to get an RF watt meter to go behind the amp, so that just added more to the total. Arrghhhhh....!

Thanks again, 73 - Jim

You just discovered why the AL-80B is actually a better deal.

Newer tube, much more powerful; larger power supply; built-in "inrush currect protector" (soft-start circuit, part of the base design); built-in PEP wattmeter/SWR bridge; and even an RF-actuated biasing system which reduces TX standby current to zero, saving some heat and electric power.

I have no clue why anyone buys the AL-811, when by the time you add these features, it costs as much as an AL-80B and still only runs about 60% of the power.


Title: RE: AL-811HD - Three Questions
Post by: KE3WD on December 28, 2012, 07:53:46 PM
Congrats on the new gear, Jim.  You should be able to get a lot of use and FUN out of it. 

And that's really what its all supposed to be about. 

"Don't let anybody steal your joy!" 

Enjoy,

es 73


Title: RE: AL-811HD - Three Questions
Post by: N7WR on December 29, 2012, 09:00:38 AM
Having owned a LOT of amps over the years I agree with those who suggest the AL 80 (A or B).  Run it on a dedicated 120VAC circuit and you will be fine.  I currently use an AL 811H with 811 tubes, run on a dedicated 120VAC circuit and never run at more than 550 watts.  Works great.  No real advantage to 572B's over 811's.  In fact the quality of 811's is better than the 572B's currently available.  No need for an amp interface either.

If you need to re-tube an 811 amp I suggest RF Parts.  If a tube goes soft during the warranty period they are great on providing a replacement under warranty. Finally, the 10/12 meter mod is simple.  Info on which wire to cut (already suggested by another) as well as photos depicting exactly which wire are available on line.


Title: RE: AL-811HD - Three Questions
Post by: KH6AQ on December 29, 2012, 09:07:53 AM
Jim,

you will have fun with your AL-811. Where are you ordering it from?


Title: RE: AL-811HD - Three Questions
Post by: W6JHB on December 29, 2012, 10:35:45 AM
The order was placed on Friday afternoon with DX Engineering in Ohio. Shipping is less than $13 and NO sales tax, so that saves me about $60 initially. I did look at RF Parts and see they have matching sets of 811A and 572B tubes offered. So, if the 811A's crap out I can see about getting replacements there. Hopefully it'll be a while before I need to do so.

My initial plans are to run the AL-811 on a 117V line in the shack and see how it works. My K3 is solar / battery powered using three 120 aH AGM batteries in the shack, so there will be no 117V load from the K3. The AL-811 will pretty much be on it's own 117 circuit, so it might do OK there. We'll see.

Jim,

you will have fun with your AL-811. Where are you ordering it from?


Title: RE: AL-811HD - Three Questions
Post by: K4RVN on December 29, 2012, 11:25:58 AM
Jim,
I have owned my three tube AL 811 for 3.5 years now so can give you some advice that you can consider if so inclined. When you remove the cover to take the packing from your tubes, make sure all the screws are  in the sockects especially the ones grounding the grids. Also check the entire amp for missing screws and extra screws and nuts lying around the amp. Look it over really well including all the wires for any missed solder joints or splatters.
My tube socket was missing a screw and nut which grounded the grid and the antenna connection had no screws and fell inside when I was connecting the antenna. Despite these minor faults I love the little amp and have had no problems since the initial inspection. Also, tune it with a watt meter and take it easy on the tubes by running about 400 to 500 watts for a time. My 811As are still doing great and I now run it about 500 to 550 watts most of the time. It gets great reports connected to an Icom 7200. You don't need any extra parts, etc. for ten and 12 meters. A simple mod. can be had by sending the place you bought it a copy of your license by email if required. Learn to tune the amp quickly using the presets in the manual as a starting point. This is the lowest priced amp for the watts I have found and that's why so many newbies to amps abuse them and blow tubes, etc. That is not to say that some of the tubes are indeed faulty to begin with. I also have the AL 80A with the 3-500 tube which is a better amp but cost almost twice as much. The soft start is not neeeded in this amp and 120 volts with #12 wire should do fine for a good stiff supply. Also 572 tubes won't give you any more output but they are more rugged and stand more tuning abuse if you happen to get a good set on the initial purchase.
I would suggest copying the page from the manual several times to allow you to keep a copy of the presets for your own antenna to cover each band. Ameritron has the page in the manual for your convenience. Its a great little amp and good luck to you. Also Happy New Year.

Frank


Title: RE: AL-811HD - Three Questions
Post by: W8JX on December 29, 2012, 12:25:13 PM
Also 572 tubes won't give you any more output but they are more rugged and stand more tuning abuse if you happen to get a good set on the initial purchase.

Basically true if you run the 572's at 811 drive plate current levels. Given that you could run higher plate current on 3 tube unit and safely run 600+ma total on 572's (which you could run on 4 811's) and get higher output levels.  Since both amps use same power supply this is possibly. On 4 tube 811 amp there is no power left so you will not be able to push 4  572's harder like possible in 3 tube unit. That being said nothing really gained with 4 tube amp using 572's because of power supply limitation but in a 3 tube it could be viable.   


Title: RE: AL-811HD - Three Questions
Post by: W6JHB on December 29, 2012, 03:05:09 PM
Great info and comments, guys! This will actually be my fourth amplifier. My first one was back in the early 70's - a homebrew pair of 572B's. Due to complete operator stupidity, that one nearly put me in the SK listing in QST. The plate cap assembly popped off and hit my right thumb, while my left hand was on the chassis. Burned a hole in the end of my thumb and knocked me across the room. 1,700 volts is pretty unforgiving. I disassembled it and never looked at it again. My next amp was a Heathkit SB-221. Very nice amp, but for a rig with two 3-500Z tubes, weak. I now understand that was mostly due to an "underpowered" power supply. Kept it until the mid 90's and eventually sold it. As I mentioned in my first post, I recently had an Elecraft KPA500 but sold it after about a year.

With those last three amplifiers, I never drove them to full output - I always thought it was akin to driving your car with the gas pedal floored all the time! The KPA500 had the ability to put out about 600 watts, but when I used it, I usually kept it to about 500 - 525 watts. I'd be willing to bet that the extra 50 watts or so would never be noticed on the receiving end. And, it just has to help the longevity of the amplifier's components. So, with the AL-811 that's been shipped, it'll be kept under 100% output, too.

I'll certainly take a good look inside after I unbox it, as I've now read several posts about the poor workmanship that may be encountered. Hopefully MFJ / Ameritron has also seen those posts and addressed them, but one never knows.

Also, I got a quote from a licensed electrician on having a separate 240V line run to the room the shack occupies. Flat rate of $250. Not too bad, and certainly a good backup option if I'm not happy with 117V operation.