[Amps] input matching question on the YC156?

[craxd]

Bill,
In any amps I've made, I did kill the B- lead for the HV until the 
antenna relay pulled in even though it was biased to cutoff on idle. The 
reason being is that if the bias ever failed while the amp was at idle, 
you'd have a run-away situation that would happen fast. On tetrode amps, 
the screen has to be killed with the B+ plate. This is an extra I always 
did but the cost keeps the manufacturers from adding it. This will also 
kill an amp that might be prone to self oscillation on idle. I'm not 
saying that what they do is a design flaw but I'd like to see all of 
them include it.

Will Matney


Is this true even when the tube is biased into cutoff?  I've owned
four commercially-made amps and all of them apply HV as soon as the
power switch is turned on, but all four have the tube biased into
cutoff.  Are you saying that is a design error?

--
Bill W6WRT