[R-390] Continuing on the R-390A .........

[pete wokoun, sr.]

Mouser sells a 10 ohm pot that works perfectly.

Xicon/Alpha 24mm Wirewound Potentiometer
24MM WIREWOUND 10 ohm

Makes zeroing very easy.

pete, KH6GRT






>From: Bob Camp <ham@cq.nu>
>To: windy10605@juno.com
>CC: r-390@mailman.qth.net
>Subject: Re: [R-390] Continuing on the R-390A .........
>Date: Sun, 09 Feb 2003 19:38:06 -0500
>
>Hi,
>
>Odd thing about the 10 turn pot modification. You really need a different
>value pot. Strange but true ....
>
>If you take a look the pot has a 22 ohm resistor across it. When the pot is
>set to the high end the parallel combination comes out to 18 ohms. The
>combination is in series with a 680 ohm resistor so it's not like they had
>to do it to keep anything from burning up.
>
>I have checked a couple of radios and have yet to find one that comes up
>with more than 15 ohms for the combination of the pot and the 22 ohm
>resistor. Normally they seem to run around 7 ohms or so.
>
>If you can get your hands on a 20 or a 25 ohm pot that should improve the
>situation over the stock part 3 or 4 X. Of course you would have to change
>the 22 ohm resistor but that's pretty easy to do.
>
>Another way to do it would be 5 ohm pot with a selected resistor in series
>with it. Again you could use a small single turn pot rather than a big ten
>turn job. Getting the 10 turn pots under the bracket can be a pain.
>
>     Take Care
>
>         Bob Camp
>         KB8TQ
>


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