[Yaesu] FL-2100B Question.

[Dr. Gerald N. Johnson]

On 7/10/2014 9:21 AM, Gary H. Harmon, Jr. wrote:
> Restoration is almost complete on a FL-2100B amplifier.  Massive cleanup,
> installation of a three wire cord and repainting the cabinet from black to
> grey and the trim ring to its correct color.  Fans also needed cleaning and
> a relube plus some screw replacement to make it all look nice.
>
>
>
> In the SWR circuit are two variable resistors, VR1 and VR2 but I don't see
> any alignment instructions in the manual.  Does anyone have the process?
>
>
They set the impedance match of the coupling wires to the main coax. I 
wouldn't adjust unless I found the SWR indicated different from my 
tuner's meter or my best dummy load.

I'd adjust this way. With the amp not keyed (no need for power at all) 
and a perfect load on the output connector, apply drive to the input, 
probably 28 or 29 MHz for the greatest sensitivity, set for reflected 
power, and adjust VR1 (reflected side) for minimum meter indication. To 
adjust VR2, put the dummy load on the input connector and the drive on 
the output connector and the switch set for forward power. It won't 
affect those adjustments to turn up the sensitivity on the SWR set pot 
to see the null deeper. Use whatever drive power it takes to get a good 
reading on the forward scale. When set for the second adjustment, the 
neatings of Forward/Reverse on the switch are reversed.

73, Jerry, K0CQ
>
> 73,
>
>
>
> Gary H. Harmon, Jr. - K5JWK - HAM Radio Archaeologist
>
> 6003 Archwood
>
> San Antonio, TX 78239-1504
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> 210.657.1549h / 210.884.6926c/t
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>
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