[Kenwood] TS-850 Transmit filter problem (FIXED)

[Don Winn]

I have found the problem with the 30 meter band not having any output and 
blowing fuses.
What I found was a pinched wire at the back of the Automatic Antenna Tuner. 
This wire (10M) goes from Q1 to relays on both the Filter board and Antenna 
Tuner board. Normally it is low and when selected is pulled to 14 volts 
with Q1 on the Filter card. With it being pinched (grounded), Q1 was 
drawing excessive current and would quickly fail. The wire was not always 
shorted which made troubleshooting more difficult.  I also found in the 
service manual that TB0-3 on sheets 29 and 30 are backwards. 1=0 and 0=1.
Don  AF4Z




At 09:44 PM 04/06/2005, Don Winn wrote:
>I am trying to repair a 850 which first showed a problem of no RF output 
>and if the output was set to max, would blow the fuse.
>I have found that the correct transmit filter is not being selected  with 
>the control lines TB0-TB3.  The logic levels are inverted for all 
>frequencies from what is in the Service Manual..
>
>I have tried resetting the radio .  All the other outputs from IC3 appear 
>correct.
>
>Has anyone else had this problem?
>
>Don  AF4Z
>
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