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

[John Parkins]

Hello Steve,

Tuesday, September 20, 2005, 9:19:04 AM, you wrote:


ST> You could see the same effect if the tank coil inductance is too low -
ST> eg if part of it  was shorted out when it should be in circuit.

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

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

ST> Steve

I was wondering about the tank coil although I've not noticed a
problem with it visually, perhaps adding a turn or two??

The HT runs at 2100 off load and 1950 on load. As I've said in other
replies I have a spare set of valves and switching them around hasn't
helped.

Gain and output seems to be OK, although I've seen that some say they
get more output, on 80 & 40m 80w in gets around 625 - 650w out. As far
as the anode current, dip it is deepest at max rf out.

-- 
Best regards,
 John                            mailto:kvp at bigfoot.com