[Amps] The maximum amount of 811As and 572Bs in parallel

[Will Matney]

Joe,

I imagine your right. That's the problem with triodes if you want to parallel them. One needs to go to tetrodes or pentodes for smaller output C. I have built some though for 10 meters that didn't use a Tune C. The output C was enough that load C was all that was required (output C equalled what tune C would have been). This was to be used over a narrow bandspread of about 50 kHz though. One could add some L before tune C making a L-Pi circuit, which has been done before. However, when it get's into paralleling that many, it would most likely be cheaper, and less complicated to go with 1-2 larger tubes.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 7/23/06 at 1:37 PM crawfish wrote:

>I have an article using 6 of the 811A's in parallel for 160 meters from 73
>Magazine, early 1980's. I would imagine the output capacitance of more than
>4 would be too much to tune the plate circuit on say, 15 and 10 meters.
>                                  Joe W4AAB
>----- Original Message -----
>From: "Hsu" <Jbenson at sohu.com>
>To: <amps at contesting.com>
>Sent: Sunday, July 23, 2006 6:05 AM
>Subject: [Amps] The maximum amount of 811As and 572Bs in parallel
>
>
>> Hi,
>>    I have seen some schematic diagram of amplifier, I found that the
>amount of 811As and 572Bs no more than four, Coud someone can tell me how
>much  maximum amount of the tubes in parallel?
>>   Thanks!
>>         73! Hsu
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