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wm-1 autec help

1iwilly

1iwilly

Sr. Member
Dec 7, 2008
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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
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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
 
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nomadradio said:
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
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close enough for me
 

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