Disable Auto band sensing

[KD8K]

Is there a way to disable auto band sensing on the HR500 amplifier? When I transmit on 40 meters occasionally the amps bandpass filters will switch to 80 meters and then trip offline.  

Thanks

John KD8K

[jcve...@gmail.com]

Hi John,

There is a way to disable it but please first try making it less sensitive. On the rear panel board there are three LED If you are looking from the front of the amp the one on the right is labeled RF_DET. With the amp powered on but no signel, that light should be out and when signal is applied it should light up. The light lighting up is what triggers the frequency detector.  Over on the left side on the reaa panel board is a blue pot labeled COR ADJ. If you turn it fully CCW the light will stay on all the time which I think will disable the frequency detector. But if you start with it fully CCW then rotate around till the LED goes out then a bit more, it will take a larger RF signal to trigger the detector which should reduce false band selection. If it still get the wrong band try rotating it CW more and see if it becomes reliable.

I really do not suggest disabling it because transmitting on one band when the amp is on another is a good way to destroy a very expensive set of MOSFETs.

73,

Jim WA2EUJ

[KD8K]

Thanks Jim. Adjusting COR ADJ seems to have fixed it. I did not need to disable it. It also appears to have fixed the random CW PTT drop offs I was having. Apparently those were also due to random band switching caused by auto band sensing.

Thanks again for your help.

John KD8K