[AMRadio] Old Iron

[Brett Gazdzinski]

How do you figure?
My 32v3 gets the screen voltage from the plate supply, which has nothing to 
do with the low voltage trans.
R301 is the dropping resistor.

I got my 32V3 about 30 years ago for $50.00, and at that time plugged in 
solid state replacement diodes, run it on the 700 volt tap, and have not had 
to do anything to it ever.
Same tubes, same iron, I use it as an exciter for the big rigs, so its on a 
lot, and I also use it as a standalone rig.

I have even variac the rig up to 800 volts and run it there without 
problems.

I keep waiting for something to go wrong with it, after all, how long can it 
keep going like this?
About 60 YEARS now with the same tubes?

My take on the low voltage trans is its overloaded with filament current.
I pulled all the tube rectifiers and have not had any problems at all.

Brett
N2DTS




----- Original Message ----- 
From: "David Knepper" <collinsradio at comcast.net>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Friday, February 03, 2012 7:18 AM
Subject: Re: [AMRadio] Old Iron


> The loss of the low voltage transformer can be traced to leaky bypass caps
> on the screen of the 4D32.  Also reducing the line voltage helps
> considerably.  That little transformer as Todd points out is the weak link
> in the 32V.  If it is warm to the touch, it is only a matter of time when 
> it
> fails.  I have been lucky so far in three of my 32V unit but one never
> knows.  Some folks will reduce the strain on the transformer by using
> solid-state rectifiers and lifting out the 807 modulator tubes if they are
> using the transmitter on CW.
>
> There was an article on this subject in an earlier Collins Journal.
>
> Replacing the low voltage transformer with a new one can cost you big 
> bucks,
> unfortunately.
>
> But, Gary can do the job for you.
>
> David Knepper, W3CRA/W3ST
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