MFJ-1924 Mobile Screwdriver Antenna Controller Settings

I have been using an MFJ-1924 Controller on my HiQ 4/80 mobile antenna for a number of years. The Controller started having an issue when it was very cold outside (very cold here in VA is < 30 F.). It seemed like an intermittent connection, causing me to fail to get pulse counts from the antenna to the Controller. The result was that I could not use the PRESET buttons to get to stored settings reliably. Since this one was getting old, and it was my only means of antenna control, I bought a new one.

I installed the new one, and all was well, for awhile. Then is started failing in a different way. This time, when it was failing, the antenna could not be moved at all. No PRESETS, and I could not use the UP or DOWN buttons. So I started to suspect the antenna or my wiring between the antenna and the controller. More troubleshooting to do.

I built a couple test harnesses, so I could use either Controller at a position right next to the antenna. Results were interesting. The old one seemed to work fine (it was only about 45 Deg F, so this is not conclusive on the original COLD issue). But the “new” one (2015 vintage) could not be used to raise or lower the antenna at all! So I did what all Engineers do as an ultimate last resort – I sat down and read the manual. I learned something about this Controller.

There is an antenna Stall Current setting, which is supposed to default to 0.75 Amps. They warn you to calibrate the Stall setting for your particular antenna. Since the original Controller worked fine with my antenna, I did not check settings on the newer one. Checking the Settings on the two Controllers, one was indeed set for Stall Current of 0.75 Amps. But the newer unit had a setting of 5.00 Amps. I am probably lucky I did not damage the antenna (or Hi-Q put protection in it, that saved me from myself). I adjusted the Stall Current setting to 1.00 Amps which seems like a good number for my motor. Now the new Controller works just fine.

I am a little worried about the 5.00 Amp setting, which I should never have seen. Hopefully it will not return. In the mean time, I will be carrying my spare Controller with me in the upcoming VA QSO Party. If you are not familiar with the VA QSO Party, please check it out and look for me as KG3V/M this year.

73, Tom




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