[Collins] Collins 30L-1 misbehavior

[Jim M.]

I had borrowed a 30L1 once that did this when I turned it on.  I was
going to buy it but gave it back ... as I recall it had something to do
with the grid circuit in the 30L1.. the 30L1 relay, if my memory serves
correctly, is keyed or unkeyed by the transmitter by applying or
removing the grid bias supply to the tubes.  The 30L1 bias supply
actually powers the relay.  There was also a fried 47 ohm grid resistor
in this particular amplifier, indicating that one tube was drawing high
grid current.  I suspect that one of the tubes had a shorted grid and
was drawing current through the relay as soon as the power was turned
on.  This of course activated the relay, hence no received signals. 
Anyway, I never diagnosed it any further but there did seem to be a
connection to the grid circuit, oddly enough.  Try another set of tubes.
N4BE
"Dr. Gerald N. Johnson, electrical engineer" wrote:
> 
> Switching the amplifier power on shouldn't change the contacts in use or
> the pressure on them, so shouldn't change the received level. As Knepper
> points out, it sounds like a control line is being activated by that
> power like his leaky bypass capacitor. That's where I'd look. E.g. the
> amplifier IS being keyed though not necessarily by the exciter.
> 
> 73, Jerry, K0CQ
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