A Call for Help.

[VE3QVC]

Hi All,
I have a Kenwood TM-271A with an issue I am hoping someone can diagnose and correct for me.
Anytime I key the radio to transmit, the power shuts off briefly. If I hold the PTT key it will re-power before releasing the key. I have tried three different power supplies, all exhibit the same problem while the radio is connected. To add some excitement to this problem, this is not a constant problem, just a "most of the time" problem.
Are there any club members who would like to take a crack at figuring this dilemma out? It has been going on for maybe a couple of years now and seems to be getting worse.
Thanks,

Philip

[Rob_Walker]

I had the same problem with mine and the hot lead had a loose connection.  My loose connection was at the PSU.

73 Rob

[Tom VA3TS]

First step is to see what the voltage is doing as close to the radio as possible. Use straight pins to pierce the conductors so you can read the voltage with your multimeter. Key the radio and see what the voltage does while its under load. If it drops look for less than perfect connections at fuses or connectors or indeed at the power supply itself... 73

[VA3KOT John]

This sometimes happens with other radios if you transmit into a high SWR. It has happened to me when I accidentally key the radio without connecting an antenna. The transmitter's foldback circuitry will appear to briefly shutdown the radio to protect the finals. Check the antenna to make sure the coax is good at both ends or try a different antenna or dummy load.

You may also be interested in a TM-271A forum on groups.io:
https://groups.io/g/tm271a
If you can't diagnose the problem from the suggestions here you could try asking for help there. Good luck Philip.