My last amp project ( 3cpx5000a7 ) required a pretty hefty PS. I used a
couple of the transformers that were pulls from the Henry RF gens running
the 3cx3000a7 tube. On the secondary of each transformer I used full wave HV
diode modules, combining the rectified dc HV from each into a common B+
using only one oil capacitor at 24 mf. Seems to work pretty good.
Bill, aren't the power transformers used in the Henry 2000 and Henry 3000 RF
gens the same? I don't know what the ratings are for them but, judging from
the weight, I believe a single transformer would easly handle 4 KW PEP out.
Larry N5BIP
----- Original Message -----
From: "Bill L. Fuqua" <wlfuqu00@uky.edu>
To: <craxd1@ezwv.com>
Cc: <amps@contesting.com>
Sent: Saturday, May 22, 2004 6:31 PM
Subject: Re: [Amps] Note on paralelling transformers
I have a 5KW Henry Radio RF generator (20 meter transmitter?) in the garage.
It has two plate supply transformers in parallel. The 3KW version only has
one o f these transformers.
To check secondarys put them in series and measure the voltage output. If it
is high reverse the connections if it is not make sure that the low voltage
that you measure divided by the transformers secondary resistance is very
small compared to the current rating for the transformers.
73
Bill wa4lav
-----Original Message-----
From: Will Matney <craxd1@ezwv.com>
To: "amps@contesting.com" <amps@contesting.com>
Date: Fri, 21 May 2004 12:43:37 -0400
Subject: [Amps] Note on paralelling transformers
I figured I might as well add this because home brew amps have used
paralleled transformer in the past to either increase the voltage or the
current. When connecting the transformer windings, they must be "in
phase" with each other. Some transformers is hard to connect this way
because the have two of the same color wires for each winding. If the
transformers are connected "out of phase" they will buck each other.
When this happens, you would get little or no output voltage and they
would act like they were shorted. You will know when this happens
believe me. You'll get a BIG hum and the fuse will open. Hopefully it
wont damage the windings too! When winding transformers or ordering
them, always have a different color wire for the start and stop of each
winding. This way it is easy to keep them in phase with on another. On
the schematics you'll see a black dot at one leg of each winding. This
is put there so you will know the correct connection to keep it in
phase. On transformers with the same color leads like two black wires
for the primary, you will need to find which goes to the start and stop
of each winding. For parallel operation the two starts tie together and
the two stops. In series operation, you will have a start and stop
together with the other two going to the line. Anyhow, I've wrote about
all I can think of on this so have at it!
Will Matney
US Amp
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