KENWOOD TS430
LATIN31
I have a TS 430 radio that has a problem with the out put power when
transmitting on SSB. When I first start operating the radio it works okay, but
after few seconds of operation or some times after few minuts the the out put
power goes dow to just few watts.
Does anybody have any ideas on how to fix this problem?
Please send any replay to Lat...@aol.com
Thanks
Jose (KC7KXN)
Scott Dickson
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I had the same problem, and can tell you how to fix it.
The RF power transistors are riveted to the Printed Circuit Board, and
the connection goes to high resistance/open circuit intermitently.
The fix is to solder those connections. Full details are below.
Below are several other items of interest pertaining to the Kenwood
TS-430s.
--Scott, KD5CAS
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KW TS-430 TX probs
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This sounds suspiciously like a problem I had with my 430 on voice.
It would behave quite similarly, losing power and becoming distorted
on an occasional basis. There was a well reported problem with early
430's where the finals were riveted, but not soldered, and the rivets
could eventually develop a high electical resistance, with ensuing
power problems. This was diagnosed and corrected by Kenwood early, so
I doubt it would be a problem in a unit manufactured as late as yours.
(I bought mine in late 1984, and it already had a modified PA --
believe me, I checked!)
My problem turned out to be a marginal connection in the internal
switch on the XVTR jack on the back of the rig. This is the connector
with 8 pins. The switch is integral to the connector and works when
the plug is inserted. The fix was to insert and remove the plug in the
jack several times. Since I have done this, my 430 has never shown
this symptom again.
====================
To all Kenwood users:
The 430 has a corresponding problem to the older rigs:
specifically the 520(S), 820(S), 530S, and 830S rigs....
Power drops while running... if this occurs, tighten the screws on the
driver board and IF board.
Had this happen to me and friends a few times...also watch out for the
coax connector on the back...they get loose too...no lock washer on
the back
.-----------------------------------------------------------------------------------------
I had a similar problem with a 430. Mine was intermittent. Finally one
cold day it became permanent. I traced my problem to an open via
connection on one of the final transistor bases. This resulted in that
device not getting a dc return to ground. I re-soldered the via to
my success!
I found it by checking dc bias on each final transistor and found one
being different in voltage reading.
===============
KD7EV advises intermittent power output problems on his '430 was cured
by installing a more conventional nut on the rear panel UHF style
antenna connector. Apparently a faulty ground connection at this
point caused a change in the VSWR which affected the sensing circuit
and thus reducing the RF output power.
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Subject: TS430S intermittent power output
A recent bulletin, from WA2PAY, asked for help for a TS-430S which had
intermittent power output; it would suddenly drop to ten watts, then
go back to full power on its own. Interestingly enough I just
recently fixed a TS-430S which had precisely this symptom. The
intermittent nature gave me fits, since there was nothing I could do
to it to make it come and go. I tried heat (hair dryer and running
the rig under a towel on the bench), cold (overnight in the fridge),
beating, pounding, thumping, probing, all to no effect. The problem
finally turned out to be bad feedthroughs in the base circuits of the
final amplifier. The base leads of the finals are soldered onto PCB
foils on top of the board. They go nowhere else on the top. The
signal is carried through the board to the foils on the bottom sides
by some feedthrough rivets. When I lifted out the final amp PCB, the
bad feedthroughs were immediately obvious. (I have been fixing bad
rigs for years and years, and solder joints are always a prime
suspect). There were some very obvious cracks in the solder around
them, and they were only making contact intermittently. Soldering
them with sufficient heat and solder cleared the problem. I also
found a few bad solder joints on other parts of the PCB, by the way,
but the ones on both final amp transistor bases was the main cause of
the trouble. By the way, if I kept the key down continuously while
the rig was in the ten watt mode, one of the base resistors eventually
started to smoke. If you have this problem, inspect all the resistors
in the base area of the final amp PCB for signs of overheating. In
many cases, they will be burned. Over the years I have cleared a lot
of problems in a wide variety of Kenwood rigs, both HF and VHF, by=20
resoldering PCB connections. It never hurts to give the evil eye
to the solder side of PCBs when you have problems.
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