[Kenwood] TS-940 LPF board relay chatter.

[Jon L. Turner]

Hello to All,

I have a question on one of my TS-940SAT radios and wonder if anyone else has run across this. After being turned on for a short period of time the relays related to the band I have the radio set to will chatter. When this happens it will not transmit but it does not effect the receiver other than the noise. They will clatter a bit than it is OK. I at first figured it was a bad relay until I did some checking. The power seems to drop off to 0 going to the respective relays. When they are at 0 in the LPF unit it will not transmit. Once the power comes back it is OK until the chatter starts again. Also thought it could be a CSJ and looked it over very close. Touched up a number of joints with no luck.

I did some voltage checks and was able to trace the voltage back to IC3 that actuates the relays. The 22.6 volts seems to drop to 0 out of the respective leg of IC3, a 7-UNIT 300mA SOURCE TYPE DARLINGTON TRANSISTOR ARRAY WITH CLAMP DIODE DESCRIPTION M54561P.
 The imput voltage seems to be there at all time on IC3. Even when the relays drop out it is still thereto the input side.

Has anyone else ever run across this problem with a TS-940SAT. I have to of these fine radios and use them about the most of all that I own.

Thank you in advance.

Jon