[Elecraft] KPA500 & Drake TR7

[ab2tc]

Hi Marcel and Don,

The TR7 is rated at 250W *input*. See here:

https://www.universal-radio.com/catalog/hamhf/tr7.html

With typical efficiencies seen in solid state PAs it is probably rated at no
more than 100W output, so the KPA500 should give you noticeably more power.
Anyway, Don's suggestion to use a constant (but variable) negative voltage
applied to the ALC input of the TR7 should work. Make sure that it is well
filtered, as any noise or hum will (AM) modulate the RF signal.

AB2TC - Knut


Don Wilhelm wrote
> Marcel,
> 
> Can you add a "Power Control" to the TR7?
> It may be as easy as applying a constant negative voltage to the ALC 
> input.  That constant ALC voltage will not cause the problems 
> encountered when using the dynamic ALC voltage that is applied from the 
> amplifier.
> 
> 73,
> Don W3FPR
> 
> On 1/12/2019 12:59 PM, Marcel Jorba via Elecraft wrote:
>> Greetings from Barcelona
>> I have here a K3-KPA500 setup that runs great
>> I also have a TR7 and I am thinking about using it together with the
>> KPA500 The obvious problem: The TR7 delivers a lot of watts (200 pep).
>> Is it an idea to discard? Or is there any reasonable approach to? ALC
>> control is not a good idea I think
>> As an alternative (500-1000 W), is there any small (in size) linear to
>> consider? I don't want to go back to the big tube linears. The KPA500 is
>> great for what I want to have here.
>> 73s de Marcel - EA3IN
> <snip>





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