[Amps] [BULK] - Re: SB200 loading problem

[Steve Thompson]

Steve Katz wrote:
> It's not normal for the LOAD cap to be fully meshed on any band when
> operated into a 50 Ohm load.  On 80m, a 500pF (I think) padder is switched
> in parallel with the tunable LOAD capacitor, but it's not in the circuit on
> 40m or the higher bands.  If that cap were missing or bad (or the switch
> wasn't making contact in that position), that could explain why the LOAD cap
> needs to be fully meshed on 80m, but it wouldn't explain 40m...-WB2WIK/6  
You could see the same effect if the tank coil inductance is too low - 
eg if part of it  was shorted out when it should be in circuit.

Max load cap. gives you a high anode load resistance. The circuit might 
like this if the ht was higher than intended, but I can't see runnning 
240V into a 220V input, for example, making enough difference. Tired 
valves that don't have the emission to cope with a lower load resistance 
might also do it.

What gain and output power are you getting, and how do they compare with 
the spec. for the amp? Does the anode current dip - is the dip at max rf 
output?

Steve