Date: Fri, 13 Feb 2015 15:41:18 -0600
From: Ed Hatcher <ed.kv5i@gmail.com>
To: amps@contesting.com
Subject: [Amps] Still looking for 7.5 volt, 42+ Amp filament
transformer
Close to North Texas if possible.
73,
Ed-kv5i
## U may have to get one from hammond, who bought out the dahl line,,,or else
where.
Plenty of xfmr makers.
## IF using a bifilar, even real heavy duty type, watch out, the fil V at the
socket will be slightly
less than at the xfmr output..... under load. My 3CX-3000A7 is 7.5 v at 50
A. Bifilar
is rated for 60A CCS. Fil V at the socket, even with rock solid connections
is only 7.1 or 7.2 v.
No big deal in my case, since the xfmr I used is a 8.25vac at 80A CCS
unit..with a 208 vac
single phase input. I have to use a small variac anyway... to drop the V down
to where I want it.
## But to get 7.5 vac at the socket, requires 7.9 vac at the xfmr lugs...
UNDER load of 50A.
## On my 3CX-6000A7 tube, it is 7.0 vac at 80A CCS..at the socket. I had
to use a 7.5 vac
rated xfmr...80A CCS... plus variac, to get 7.0 vac at the socket...again,
I lost .4 vac through the
80A CCS rated bifilar.
## Just something to be aware of. If u get a custom built one, get a few taps
on the primary.
Jim VE7RF
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