The primary to secondary short is a known problem with the 425's, and mine
went back to the factory some years ago for a replacement which is still
running fine today.
You can't go wrong with a Peter Dahl transformer as a replacement, but I
would suggest calling them on the phone. Here is a link to an article
about
beefing up the venerable 425 which is good for future reference even if
you
keep the finals and the plate voltage the same. The author used a
specially
built Peter Dahl transformer for the project which turns the 425 into 3.5
kW
ground pounder!
http://www.hamradiomarket.com/articles/Titan%20P%20Hybrid.htm
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Carlin Royal" <n5oe@nctwb.net>
To: <tentec@contesting.com>
Sent: Saturday, August 18, 2007 11:49 AM
Subject: [TenTec] Titan 425 Transformer needed
Sorry for the long delay on the re-post. After replacing/upgrading the
rectifier board, installing new filter capacitors the initial problem is
still there. I carried the amp to a local repair shop and it has been
determined for sure the secondary leads have shorted with the primary in
the transformer. SOOOO I am in need of a new transformer for the Titan
425 at this time. Since I have already come this far money wise and time
wise, I think it would be best to get a "really good" transformer this
time. I have emailed Peter Dahl with no response, are they still doing
this sort of thing for amateur use?
_"I have a Ten Tec Titan 425 that I have only had myself for about 6
months now.
The amp when I received it had 1 bad HV capacitor in the power supply.
Due
to
lack of funds at the time I replaced the one known bad capacitor. A few
months
later I was operating the amplifier during a cw pileup for about 30
minutes, I
set everything on standby and went to lunch. When I returned to the shack
I
find the amp had blown one of the 20amp fuses in the supply.
After checking in the PS, I found that R1 the 10ohm 25watt wire wound
resistor
on the rectifier board had went open. I replaced the blown resistor and
powered
the amp back up, this time again blowing a 20ampfuse and the same
resistor. Ten
Tec advised to replace the original rectifer board with a new one, (82112
rev E
I beleive) since they thought some diodes were probably leaking and was
the
cause of all my troubles. Now after replacing the old rectifier board
with
the
new one from Ten TEc, I power the amp on and it blows another 20amp fuse
but
did not appear to fry the resistor this time. Here is the main question
to
the
list; Could I have another bad capacitor that is failing under high
voltage
since they do not read any shorts on the VOM when individually beng
tested. I
have on order 8 new 400uf 450v caps from Newark Electronics and will be
replacing them this week, but I am looking for more input as to the
trouble. It
just seems odd to me that when sitting idle for just 3
0 minutes the thing went south and now I have had all this trouble.
Hopefully
I am on the right track and it will be one of the caps in the PS, but
would be
interested to hear any other areas that I might could check within reason
here
on the very limited bench. Thanks for any advise/comments.
73 "_
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