Brian,
Yes indeed; it appears to be the same power supply transformer in both the
AL-811 and the AL-811H.
The conclusion I'm coming to is, IF you can run 800 watts PEP output from an
AL-811H using 3 572B's, with the fourth tube socket empty, then you should be
able to run 800 watts PEP output from an AL-811 with a trio of 572B's in its 3
tube sockets.
Of course, there may be other limiting factors in the AL-811, as compared to
the AL-811H, of which I'm not aware.
In any case, I'll continue to run my AL-811 at no more than 600 watts PEP
output, just to be on the safe side. It's not worth pushing the envelope, so to
speak, for that additional decibel!
73,
Martin
W7MJM
----- Original Message -----
From: The Zwiener
To: W7MJM
Sent: Thursday, February 10, 2011 2:15 PM
Subject: Re: [Amps] AL-811 & 572's
The power transformers are the same in the 811 an 811H
I was curious too and looked at the manuals. Talk to MIke at Ameritron to
confirm.
Have fun and be safe!
73,
Brian
KF5CCN
________________________________________________________
> Thanks Bob and all those who responded to my queries. I now have a better
> understanding of the AL-811 vs. AL811H amplifier capabilities when
> retubed
> with three 572B tubes.
>
> To be sure, I'm not looking to squeeze out more wattage than these amps
> can
> reliably, and linearly, deliver, nor am I considering a bigger amp. I'm
> happy with 600 watts and have no desire at this time for more RF power. I
> was just curious about W8JI's suggestion some time back about running
> only
> three 572B tubes in the AL-811H, presumably at 800 watts PEP output, as
> opposed to running a trio of 572B tubes in the AL-811 at 600 watts PEP
> output.
>
>> From the various comments, I now understand that the power supply in the
> AL-811H is what allows three 572B tubes (or four 811A tubes) to generate
> 800
> watts PEP output, whereas the power supply in the AL-811 is what limits
> the
> output to 600 watts regardless of whether you're running a trio of
> 572B's or
> 811A's.
>
> When you come right down to it, it's the transformer that delivers the
> power, though I suppose you could take it further up the line to the
> power
> company's generating plant. The tubes are, well, "valves" as they say on
> the
> other side of the pond.
>
> In any case, my AL-811 continues to serve me well, with good reports and
> no
> issues three or four years after swapping out the 811A's for 572B's.
>
> Incidentally, when I removed the 811A's, which I had been using for maybe
> three years at the time I swapped them out, they showed the tell-tale
> silver
> plate welts, indicating that I had overheated them; sufficient reason
> for me
> to go to 572B's for their additional anode heat dissipation capabilities.
>
> 73,
> Martin
> W7MJM
>
>
> ----- Original Message -----
> From: "Robert Kirkland" <alpha76@triton.net>
> To: <w7mjm@arrl.net>
> Sent: Wednesday, February 09, 2011 7:17 PM
> Subject: [Amps] AL-811 & 572's
>
>
>> Martin,
>> The amount of plate current a triode tube will draw depends on it's
>> plate
>> voltage. The 572B is usually operated from 2200 to 2700 volts. The 811A
>> usually operates around 1500 to 1800 volts, be careful, some brands of
>> foreign 811A's are not rated for as much plate current as is necessary.
>> The full load voltage on the AL-811 is 1500 and the plate current is 550
>> ma. That's about 600 Watts output, with the 572B's there is not enough
>> plate voltage and plate current to produce much more. The only reason to
>> install 572B's is, used at these low ratings the tubes will last forever
>> and you won't over heat them on a long tune up. You could increase the
>> voltage by messing around with the power transformer primary input
>> settings but then the filament voltage would be way out of limits and
>> surely the transformer would over heat. If I had an AL-811 Linear and I
>> wanted more power I'd trade it in on another amp, or try to improve the
>> antenna.
>> Bob,
>> w5pvr
>>
>>
>>
>>
>>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
--
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|