[Amps] 3cx800a7 Grid Current Problem

[paul at greenrover.demon.co.uk]

On 26/01/2012 07:14, Mike Tubby wrote:
> On 26/01/2012 02:40, TexasRF at aol.com wrote:
>> About a month ago, JE1BMJ reported a similar problem with his SB1000. In
>> his case, the problem was found to be inadequate bypassing of the plate rf
>> choke. Apparently enough rf was reaching the bypass capacitor to heat it up
>> and  cause it to change value and that was enough to detune the plate circuit.
>>
>> 73,
>> Gerald K5GW
>>
>
> This appears to be not uncommon across several amp designs - even the
> venerable TL-922 shows lower output on 160m than it does on 80m/40m and
> no doubt if the input power is there then the output is going
> somewhere... okay in the case of the '922 it might not be causing
> de-tuning and grid current but I bet soemthing's getting warm ;-)
>
> Mikie G8TIC
>

Hmm.. the original LAUK Explorer using a GS35b has the same problem, 
more bypass C needed for reliable (SIC) operation on the low bands.


73 de Paul GW8IZR


-- 
73 de Paul GW8IZR IO73TI
http://www.gw8izr.com