[Amps] Help with ARRL handbook design 4CX1000A 2m PA

[Pete Lindsay]

Hi all and thanks for the quick replies!

>Is there something running hot in the output circuitry? Capacitors,
stripline, coil etc.?

Not that I can find.

>Or insulating material with high absorption at 2M

The only insulating material in the tank circuit is PTFE. I have also
checked for any ferrous material in there that might cause problems.

>What's the bias? Is it running class A?

The idle current at 250mA as per the design.

>You should send this mail to Don, W4OC. He and I have both built this amp
and enjoyed great success.
He still has his and should be able to help you.

Thanks for that, will do, do you have his email address?


Pete


2008/7/21 Roger (K8RI) <sub1 at rogerhalstead.com>:
> Pete Lindsay wrote:
>>
>> Hi Guys,
>>
>> I have a 2m PA built around the design in the 1986 ARRL handbook
>> chapter 31 using a 4CX1000A. It was built by a friend to a very high
>> spec and looks like an exact copy of the original design. The problem
>> is it has never really worked that well. The problem lies in the
>> output efficiency which, at best, is only around 30-35%. I am using
>>
>
> What's the bias? Is it running class A?
>
> 73
>
> Roger (K8RI)
>
>