[Kenwood] TS-940S

Troy Warren k5ohtroy at wildblue.net
Thu Nov 20 23:51:34 EST 2008




I just acquired a TS-940S/AT that appears to be in very good condition 
except it has a transmit audio problem. Would appreciate some help on this. 
This is my first Kenwood HF radio. Maybe someone has had this or similar 
problem with this rig. Would also like to know if there is someone who works 
on these radios in case I can't repair it. Here is what I have done so far. 
The receiver works great.
All of these tests were done with the radio connected to a dummy load and 
the RF control at minimum ( I also tried it at various power levels. I 
checked the output (key down in CW) with a bird wattmeter and it was 100 
watts plus on all bands.
 I hooked up a brand new, out of the box, MC-60 microphone.
I pushed in the "MONI" button and keyed the mike. I talked into the mike and 
increased the mike gain to about 9 o'clock (number 2 on the dial) while 
watching ALC on the meter. The audio sounded great. I turned on another 
receiver to monitor the audio and it was very distorted and the ALC meter 
was very erratic.
 I removed the top and bottom covers and checked all of the connectors that 
I could see on the IF, RF, and Control units (boards). All looked okay. I 
removed all of the plugs (connectors) on each of these boards and coated 
each pin with a Deoxit pen and plugged them back in to their receptacles. I 
also lowered the front panel and did the same for all of those connectors. I 
also checked the battery voltage on the back of the sub display. It was 2.94 
volts DC. The problem still exists. Receive still works great and all of the 
dosplays are good.
I don't think it is the microphone because the audio sounds great with the 
MONI button pushed however I do not have another mike to try.
After looking at the block diagram it appears that the IF unit (board) may 
be okay since the MONI feature is near the output of the board.
Any help would be appreciated.
email:  k5oh at mptelco.com

Regards, Troy, K5OH 



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