[Kenwood] Kenwood TS 570D Problem...

[Ken Burrows]

I have a problem with my TS570D transceiver...

On the 30 meter band sensitivity very low and there is no transmit
output. This has been this way for some time.

I have investigated with the service manual info and the problem
seems to be in the bandpass filter section in the front end.

There are  9 bandpass filters eg. 7.5 to 10.5, 10.5 to 13.0 etc.
The receiver section dies corresponding to these bandpass parameters
eg. no output 7.5 to 10.5 and then at 10.5 sensitivity comes back to 
normal. There is also no transmit RF over the faulty receive range.

The print shows two switching diodes, one at the i/p and one at the 
o/p of each filter, I assume these are biased on as the tuning dial
rotates past the filter switching frequencies.

I had been living with no 30M band, but yesterday the 80M band started
to show the same fault.

Has anyone else had a similar problem with this model?

Any tips re fixing the same? I assume i will have to replace the
switching diodes, it looks like a big job, as one diode is on the
top of the board and the other is on the underside for each filter.

I dread that this is a fault that can keep occurring at random and
I will constantly be replacing the diodes????

I live in Nova Scotia (VE1) and am in the boondocks regarding
parts procurement etc...

Ken Burrows
VE1DS






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