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Faulty Yaesu FT840

Posted: Thu Oct 06, 2011 1:30 pm
by Ronald
My FT840 STOPS TRANSMITTING A FEW SECONDS AFTER PRESSING THE MIKE. THE ANTENNA, ATU AND POWER SUPPLY ARE OK. any idea what the fault could be. The ATU shows power out for a few seconds and then drops out. Thanks

Posted: Thu Oct 06, 2011 2:32 pm
by SawzAll
Just two possibilities come to mind - to me.

One, is that the antenna SWR is outside of the range of its ability to tune the antenna you are using.

Second, since the SWR cannot be found acceptable by the radio after the antenna tuner failed to tune the antenna; the radio will fold back the output power ('protection circuit') in order to protect the final output transistors.

Just an observation - BTW.

Posted: Sun Oct 16, 2011 11:39 am
by !KANT
I'm sure the tuner can tune for the radio to see a minimum VSWR [since it's an external unit.] Check the jumper cable between the rig and tuner. Also, specify whether or not it's occurring on all bands or just a particular band?? Continuing, do have any RFI anywhere at or surrounding area to the station--lvingroom, bedroom appliances??

Posted: Sun Oct 16, 2011 12:06 pm
by Ronald
!KANT wrote:I'm sure the tuner can tune for the radio to see a minimum VSWR [since it's an external unit.] Check the jumper cable between the rig and tuner. Also, specify whether or not it's occurring on all bands or just a particular band?? Continuing, do have any RFI anywhere at or surrounding area to the station--lvingroom, bedroom appliances??
Thanks for reply. Problem solved. Faulty power supply1

Posted: Sun Oct 16, 2011 10:17 pm
by !KANT
Ronald wrote:Problem solved. Faulty power supply1
Was going to be my next question, "What is the rating of your P/S??--make and model wold be helpful also"

Happy you have it solved. :wink: