Bob -
Cool!
Hopefully it had just gone up in value, as carbon comps are wont to do, resulting in toooo much
power. I replace them with a 1W "Flameproof" or wirewound or ceramic composition. Don't replace
with a carbon film or metal film. They don't do well with heavy currents.
Glad you found the CD useful. I just wish I had done it 30 years ago. It's depressing to think how
many hours of my life I could have saved with it! :-)
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Robert Fish wrote:
Hi Gary,
Thanks! That was it. R59 fried and in two pieces. I just couldn't see
it because it was still in position and appeared to be one piece.
No 3.3 ohm resistors in the junk box so I will place an order in the
AM. Maybe I will put a 1 watter in there just to increase the margin.
Your service CD just paid for itself by saving me time searching for R59.
Thanks Again Garey,
Bob K6GGO
Bob -
First thing to check is R59. It has probably gone up in value,
causing your meter to read high, and may even be the source of your
smoke.
Possible heater-cathode short in one of the Final tubes.
Also check R132 and R133. You may have had a momentary short from
one of the panel lamp socket lugs to chassis. They turn on the
socket and can touch the chassis.
Beyond that would take a little more investigation.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Robert Fish wrote:
Hi Guys,
About a month ago I was in a CW QSO using my C-line twins. While
transmitting I was getting a little long winded, nothing outrageous,
my transmission lasted
maybe 1.5 minutes at the most when a quite visible puff of smoke
arose from the T-4XC and the panel lights went out. Every thing was
dead. I have been fairly
busy lately and only now have I had a chance to try and figure out
what happened. I opened up the T-4XC and did a visual check top and
bottom and could find
no discolored or burnt components. I checked the AC-4 and the main
fuse (5 amp slo blo) was blown. I replaced the fuse and checked the
power supply voltages
everything was fine. I put the transmitter on a dummy load and it
loads up fine. The power out seems a little light. It seems like I
need an awful lot of plate current (nearly 400ma)
to get over 100 watts on 40 meters. I didn't keep it at that plate
current for very long. I did notice that the neutralization is off a
bit. I guess I should do a voltage check and a complete
alignment as it hasn't been done in a while. But I am not sure where
to start looking for the origin of the smoke. Any ideas as to where
I should start looking?
Thanks in advance,
Bob K6GGO
P.S. the 15 ohm cathode resistors are fine
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