The suggestions got me thinking -how to heat up the xfmr the easiest
way. Thanks everyone for the help by the way! (more questions below
though)
The variac was far away and mounted in a panel, and otherwise
occupied, so the heat method seemed easier.
I did drive out the moisture (I hope), using heat. I put the
transformer in a cardboard box (actually made the box around the
transformer since it is so heavy) and made a hole just big enough for
a 1500 watt hair drier to stick into. Made another hole diagonally
opposite, and fired up the drier. The drier did not blow on the
transformer itself. I monitored the temp with an HVAC thermometer. The
temp reached 160 degrees and I kept it there for 2 hours. I now have
siliconed up the messed up insulation, and all seems well.
The terminals on the transformer are marked, even the secondary, with
"P" and B+", so I am good to go there.
The suggestion to use a reactor, I have seen it done in a broadcast
transmitter in a book, but one was not included in this one.
Time for more dumb questions,
Is either of the circuits below the correct one?
Is there a formula or guideline for the reactance of the inductor and
capacitor vs. frequency response?
I have never seen actual values. I do have a pile of 10-20H inductors
and quite a few oil caps. I am guessing hi-pot to ground on those
might get critical.
I have noticed the secondary (modulated stage side) is the inner
winding on this transformer. The fact that the XFMR was mounted on a
wood base makes me wonder if the insulation of the secondary to ground
might not be intended for high DCvoltage, or maybe the builder was
being cautious? It WAS hooked up as to pass HV DC through the
secodary. -but go on about the reactor setup please, I have been told
this makes the rig sound better due to no unbalanced DC current in the
transformer core.
(In this transmitter, both MOD and RF B+ are the same, 3500V)
MOD XFMR CAP REACTOR
_________4-1000 RF CHOKE
304TH P____ __________| |_____|
)||( | | )||
)||( )||
B+_________)||( )||
)||( )||
)||( )||
304TH P____)||(__________________)||
|
B+
I have also seen this..
MOD XFMR CAP REACTOR
_________4-1000 RF CHOKE
304TH P____ __________| |_____|
)||( | | )||
)||( )||
B+_________)||( )||
)||( )||
)||( )||
304TH P____)||(_____GND B+_____)||
Which would seem to make more sense?
Thansk,
Patrick
