wm-1 autec help

[1iwilly]

This question if for those who at one time or still have one a WM-1 autec meter I need to adjust the SWR side on my MFJ-259-B which I was lucky enough to have it re-calibrated in February 2024 before they shut down. on the mfj on 40 meters say 7.205 shows a 1.7 SWR the wm-1 shows 1.4 on 20 meters 14.260 mfj 1.1 wm-1 accurate 1.1. I have the manual and I'm a tad confused as to this step #2 do I adjust for a 1.1 not 1.0=meter don't move ?? look at pic Also use the 20 scale or 200 scale because if I adjust on 20 then 200 is off power and swr

 

[nomadradio]

The trimmer capacitors serve to set the 1.0-to-1 reading at 50 ohms. Naturally this is hard to do if your dummy load isn't 50 ohms. That trimmer cap is typically called a compensation capacitor. The idea is to get this setting close with the forward-side meter, then fine-tune its setting on the reverse side by reversing input and output. Naturally a load resistor closest to 50 ohms is the only way to get this right.

If you set any of the power-range trimpots, a droplet of control cleaner on each one before you turn it will improve the odds that the adjustment will remain stable after you set it.

73

 

[1iwilly]

The trimmer capacitors serve to set the 1.0-to-1 reading at 50 ohms. Naturally this is hard to do if your dummy load isn't 50 ohms. That trimmer cap is typically called a compensation capacitor. The idea is to get this setting close with the forward-side meter, then fine-tune its setting on the reverse side by reversing input and output. Naturally a load resistor closest to 50 ohms is the only way to get this right.

If you set any of the power-range trimpots, a droplet of control cleaner on each one before you turn it will improve the odds that the adjustment will remain stable after you set it.

73

close enough for me

 

[nomadradio]

Rock on! You're good to go with that one.

73