RadioBanter - View Single Post - TS-450S output reduced

Jim KW6JIM · January 28th 12, 04:12 PM

I have a similar, yet different, problem. When I first turn on my TS450s, it works great. However, after a short time I lose my modulation. The radio will key, but no modulation moves thru it. It still seems to be transmitting the proper wattage in other modes.

Prior to this problem beginning, there were some scratchy-popping noises coming thru the speaker. I dont know if the two are related. The scratchy noise has stopped. I assumed at the time that a compontent died, but I don't know what it may have been.

Any ideas?

Jim
KW6JIM

Quote:

Originally Posted by Fred McKenzie

In article ,
rahulkapoor wrote:

3. Shack temp had become very hot last few days. Day temp in shade is
40 degrees C plus.

Rahul-

Unless you ran it key-down for an extended period in CW or FM mode, it
is unlikely that your ambient temperature caused a transistor to fail.
Power transistors normally operate somewhat higher than 40 degrees C.

Lack of any ALC reading is most likely the result of low power. The
cause of low power could be a bad transistor, but is more likely a leaky
or shorted capacitor loading down the voltage supply to an RF stage, or
a voltage-dropping resistor that has gone high in value.

Another problem you might look into, is a connector on the rear panel,
where a transverter would normally be connected. Some Kenwoods have a
closed-circuit switch built into the connector, and sometimes the switch
contacts get oxidized from lack of exercise. There would have been a
mating connector in an accessory packet that came with the radio. If
you still have it, try plugging it in several times. The wiping action
of the switch should clean up any oxide coating.

73, Fred K4DII