#20 Kenwood TM 621A deaf 220 MHZ Receive

[Radio Tech]

#20 Kenwood TM 621A deaf 220 MHZ Receive

In this video I attempt to repair the 220 MHz receiver in a 621a. I have no service information on this rig but have repaired several of them. There are no free copies of the service manual online that I can find. I use the TM-721 block diagram to trouble shoot. The 721 is a 2 meter 70 center meter unit.

 

[Robb]

So; that transistor is a typical problem with this radio?

What is causing it to fail?
Too hot of a signal?
Or is it an improperly spec'd part; or engineering problem?

 

[Radio Tech]

So; that transistor is a typical problem with this radio?

What is causing it to fail?
Too hot of a signal?
Or is it an improperly spec'd part; or engineering problem?

Really think it is more of a design issue than anything else. Have to remember there is not a lot of 220 gear out there. I think Kenwood was just chomping at the bit to get this radio on the market over looking critical designs flaws. One day when I can get a service manual I like to go in and do some testing on the front end of the 220 band. The receiver is pretty hot and may be suffering front end over load.