[Kenwood] TM 721A Service Manual

[bruce.kendall at iird.vic.gov.au]

I am looking for a copy, either hard or soft, of the service manual for the
TM 721A.

I have two of them and one has developed a problem on 70cm high power
transmit.  When I key the Tx on high power, my external analogue power
meter momentarily deflects to 35w [max power] and then drops back to a much
lower power level.  On the low power setting [5w] this phenomenon does not
occur.

I am wondering if the VSWR protection circuit needs adjusting?  I notice
from examining the circuit diagram that there is trim pot VR4 [47K] on the
Tx/Rx [430/440MHz] PCB that appears to be the VSWR protection sensitivity
adjustment.  Assuming that my thinking about the cause of the problem is
correct, I want to confirm that this trim pot is what I think it is.

Any help that can be provided will be appreciated.


Bruce R Kendall  VK3WL




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