Flex 6300 ATU

Garyh

For anyone who has experienced 6300, 5000 or other radios with add on ATU, issued with tuning not always working, Strange tuning behavior etc.

I wanted to share with everyone that there is a relay on the 6300 and all other flex ATUs that switch the RF into the ATU when its enabled or tuning and switched RF aout of the atu or bypasses the ATU entirely id its not being used.

I first experience this on 2 5000A radios I had. One had the side burned out of this relay. On the 6300 its K3 and sits sideways between the two rows of relays for the matching circuits.

My 6300 would tune once every ten tries and most of the time it would not tune at all. I checked K3 and all the contacts were shorted even the normally open ones were connected with the relay de energized.

I replaced the relay as I had done on other ATUs and now it will tune my 40 M dipole on all bands . On a couple radios I cut open the relay and it was charcoal inside. I wonder if this happens if you try to tune up with no antenna connected by mistake.

Thought this might help others who I have seen reporting ATU strange behavior.

Relay PN EE2-12NUX but a TX2SA-12V will also work

Gary K4MT