[Elecraft] KPA100 power on 20m/30m, update

[Vic Rosenthal]

Bill NY9H wrote:
> i just received 2 ka100 mod kits...... for both radios...
> 
> My question, should I be changing out the C80 & C81 while i messing in 
> there...
> or do the changes in the "ka100 MOD kit"  eliminate the need for a change.
> 
> Looks like the R19 & R20 are changed in the 'mod'  and are sitting right 
> there.

I wish we could get an official statement from Elecraft on this issue.

<begin MY OPINION>

Apparently the metal-film resistors used in this application vary widely 
in inductance.  Some resistors have an  inductance that seem to resonate 
with the capacitors near the 30/20 meter bands, basically putting a 
parallel trap in series with the drive, and causing the driver stage to 
have to work harder.  This shows up as high current and/or reduced 
output on 30/20 meters.  Hence whether or not you need to change the 
capacitors and if so to what value depends on the resistors that you you 
have.  Note that this depends on the physical construction of the 
resistor and it's (unwanted) inductance, not its resistance.

<end MY OPINION>

I guess the question is 'what capacitor value is appropriate for the 
resistors shipped in the mod kit'?

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco