Re: K3s no power on TX


Alan Baker
 

Hi Brian.

Have you checked that the rig is not in TEST mode?

RH Mode button, press and hold.

It's an easy one to miss when all else appears OK, but you get no RF output.

73,

Alan. G4GNX


------ Original Message ------
From: "Brian" <brian@...>
Sent: 18/05/2020 23:18:02
Subject: [Elecraft-K3] K3s no power on TX

Hi All

Hope you are keeping well.

I have a K3s that has no power output that appears to have failed while not in use.

In tune there is no detected output on a Bird wattmeter with a 50 watt slug. When connected to a KX3 via a 30 dB attenuator the KX3 reports an S9 for an instant when the K3s tune is pressed, quickly dropping to S5.

There are no apparent problems on RX. The KPA3 has been set to bypass for test purposes. 

The TX filter is set to 2.8 kHz for SSB and CW. Testing is mostly being done in CW.

It would seem that the problem should be in the path between the SWR bridge and ANT 1 connector ( no ATU in K3s), however, as receiver works as well as another K3s on an AM broadcast station on 40M this seems unlikely.

I suspect the 10W PA driver or the switching diodes around it.

Has anyone seen this problem that can give advice before I start taking the K3s further apart?

Thanks

Brian KF6C.

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