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AL-811H

SMILEX2692002

SMILEX2692002

Well-Known Member
Oct 26, 2011
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108
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I have a AL-811H i bought some time ago and really never used it.
I was bored so I hooked it up today and here is what I found.

On 10 meters I couldn't get more than 450 PEP on SSB from it. I got this with 40 watts drive from my TS480. When I increased the drive nothing more.

On 12 meters I couldn't get more than 350-400 PEP on SSB from it. I got this with 40 watts drive from my TS480. When I increased drive it made no difference.

On 11 meters (Shame on me) I can get an easy 500 PEP from the amp with 40 watts drive from my TS480. If I increase the drive to 50 watts I get 600 watts PEP, 60 watts drive around 750 watts PEP, and 65 watts drive gives me 800+ watts PEP.

My question.
Could someone have turned the input tunning adustment for the AUX (12/10 meters) band switch for optimum output on 11 meters?
I have no desire to run my amp on 11 meters.
Can I fix it?

All my tests were done on my Imax 2000 antenna.
I need to get a dummy load to test on to see what the outcome is in a perfect world.
 

Sounds like you do need to adjust the input impedance on the amp.

Easy enough to do if you have the proper adjustment tool.
 
NON-METALLIC hex tool 0.1 inch. Ameritron sells them and they may be available as part of a kit at RadShak. GC used to make the same sets.

And just as an "OBTW", many tube amplifiers that easily deliver rated power at 20/40 meters drop off quite a bit at the higher frequencies. Interelement capacitance in the tubes and circuitry, etc. Plus for the WARC bands, you have to make the decisions regarding which band gets your preference. Whoever owned it before you may not have had the same ones as you do.
 
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Beetle said:
And just as an "OBTW", many tube amplifiers that easily deliver rated power at 20/40 meters drop off quite a bit at the higher frequencies. Interelement capacitance in the tubes and circuitry, etc
Click to expand...
.

I go round and round with 11 meter guys in my area about this and they simply do not get it!!!!
 
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Beetle said:
NON-METALLIC hex tool 0.1 inch. Ameritron sells them and they may be available as part of a kit at RadShak. GC used to make the same sets.

And just as an "OBTW", many tube amplifiers that easily deliver rated power at 20/40 meters drop off quite a bit at the higher frequencies. Interelement capacitance in the tubes and circuitry, etc. Plus for the WARC bands, you have to make the decisions regarding which band gets your preference. Whoever owned it before you may not have had the same ones as you do.
Click to expand...

I agree.
I just found it strange that someone would take the time to adjust for 11 meter output.
I will look into getting the hex tool.
 
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TonyV225 said:
.

I go round and round with 11 meter guys in my area about this and they simply do not get it!!!!
Click to expand...

YUP! I run a Dentron Clipperton L on the HF bands and it will do every bit of 1200 watts on 75, 40,20,and 15 but only about 400 watts on 10 even with 100 watts of drive...
It gets me how these guys that buy a Heathkit SB 220 and use it on 11 meters brag "Oh it can do 2 KW!" I call BS when i hear that......:glare:
 
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A couple things,.... yes, check the input SWR on the amp on the desired band and frequency you wish to operate on. I agree with that. Also, those amplifiers aren't meant to be ran really "Hard". The 811-A tube will fall off as you go up in frequency regardless of amp design, and specifically in the Ameritrons due to design characteristics. But probably most importantly, keep an eye on plate current, and do not exceed max ratings regardless of output power unless you want to go through tubes very quickly.


The Ameritron 811-A series amplifiers are probably my least favorite when it comes to the Ameritron line, not because they use the 811-A tubes, but because they exceed the maximum ratings I would personally run them at, and also they do not cool the tubes very well or the sockets for that matter. Combine that with the design on the PI network, and you really should just run it conservatively.
 
IDK, I been running my 811 A amp at 500-600 watts on 10 meters SSB with no issues. been using the same set of tubes for about 2 years and no tube problems. I am driving it with about 70 watts I beleave but I need to check next time I run it. I do run it through a LDG 600 pro tunner with swr at 1.2.

I know some people say that they do not do this much but mine does, I tune it to the max output then back the exciter down to lower the watts coming out of amp when not needing 600 watts for the contact but maybe 200 or any where in between.

When I bought the amp it just needed to have a wire cut inside if I remember correctly to convert it to 10 meter but my memory eludes me right now.

AP
 
the 10/12 slug will adjust for best input on 10 OR 12, you have to make a choice,...... or a compromise

same for the 15 meter adj pot.
 
Staybolt said:
YUP! I run a Dentron Clipperton L on the HF bands and it will do every bit of 1200 watts on 75, 40,20,and 15 but only about 400 watts on 10 even with 100 watts of drive...
It gets me how these guys that buy a Heathkit SB 220 and use it on 11 meters brag "Oh it can do 2 KW!" I call BS when i hear that......:glare:
Click to expand...


And I bet you get out just fine with 400 watts and have no issues with getting the contacts. I think its an 11 meter thing that aslong as the meter shows MORE POWER!!! YEAH BABY IM GETTIN OUT THERE FORSURE!!! Again a QRP radio with a great antenna will do just as good but try to explain antenna theory to power mongers that are all on a power trip in a mind set meaningless power war!!!.
 
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TonyV225 said:
And I bet you get out just fine with 400 watts and have no issues with getting the contacts. I think its an 11 meter thing that aslong as the meter shows MORE POWER!!! YEAH BABY IM GETTIN OUT THERE FORSURE!!! Again a QRP radio with a great antenna will do just as good but try to explain antenna theory to power mongers that are all on a power trip in a mind set meaningless power war!!!.
Click to expand...

LOL. I have made contacts using PSK 31 and ONLY 10 watts and have talked to Germany and Ireland several times...
 
Yeah but my guess it wasn't on a band where 2,000 people were all calling CQ CQ CQ DX this is suger bananna bread loaf delta xxx break break break all with 1000 watts of overmodulated stuff while trying to make that contact so there is some power and directional antennas warranted when we are talking 11 meters. A lot of it all depends on the MUF too. 11 meters is a bit more difficult than let's say 20 meters on a clear frequency.
 
I find it more enjoying making a contact without an amp.
When I do use my 811H I find the output to be satisfactory with a 40 watt drive from my Kenwood transceier on SSB.
 
Not to derail this thread, but what amp would you guys recommend over the 811H? New, of course... not your favorite oldie but goody! And keeping with the theme, around 500 watts comfortably, 160-10, and without breaking the bank.

73,
RT307
 

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