[R-390] R-390 AGC/ Time constant

[Mike Andrews W5EGO]

On Wed, Dec 31, 2008 at 08:08:24AM +1100, Pete Williams wrote:
>   G'day...when does a capacitor  become a battery?
> In trying to sort an obscure fault in a R-390/URR agc /TC problem in a IF
> module, I've discovered that the 2 mfd TC capacitor appears to be generating
> a 20+ mV charge that won't go away.
> It's  still there  after standing still for  hours and not  affected after
> shorting--- the charge returns.
> Anyone else seen this?-Other 2 mfd caps don't show this effect.
> Changing to see if the problem in the radio is still there yet to be done.

Hi, Pete. This is a known effect, which leads makers of really big
HV caps to short the terminals before shipping them. Not all caps do
this, but some do.

Would anyone be interested in reading the story that W9LBB posted to
the Glowbugs list a few years back about the test facility at the VERY
High Voltage cap. mfg. plant? I find it hilarious and scary at the 
same time, and very definitely educational. He mentions shorting the
cap terminals before shipment as an aside, too. 

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin