[AMRadio] BC-610

D. Chester k4kyv at charter.net
Wed Nov 23 19:02:36 EST 2011


> From: Warren Elly <w1gud4 at gmail.com>
>
> My I Model sealed mod tranny has "talked back" from day one (five years on 
> air), reminds me of the
> broadcast boxes I was around as a 3dclass endorsed kid reading meters in 
> the 60ies...
>
> My beast sits 6 feet behind my operating postion...but I've operated 
> sitting in front of it as well, and never found the talk back to be a 
> problem...


Are you sure it is the mod transformer, not the overload relay that is doing 
the talking back?  The cure for that problem is to wire a capacitor between 
the midtap of the power transformer and ground - something very easy with 
the open frame plate transformer, but more difficult with the potted version 
with the terminals on the bottom.  That by-passes the relay at audio 
frequencies, but allows it to still function to pull in with an excessive DC 
load on the power supply. Use a "computer grade" electrolytic, about 100 
mfd.  The positive terminal  goes to ground and the  negative to the 
transformer.

Don, k4kyv
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