Modulation Bias Adj Pot value on Valiant

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w8khk:
Quote from: N1BCG on December 10, 2017, 07:32:23 AM

R21 (Modulator Bias) and R22 (RF Bias) are both 5k Ohm, 25 Watt wirewound potentiometers.

In some manuals, R21 and R22 are listed as R61 and R62 but the values are the same.


Thanks for the correction, Clark.  It seems my valiant, and manual, are an older version.  My apologies for the mis-information.

N1BCG:
Quote from: w8khk on December 10, 2017, 10:00:09 AM

Thanks for the correction, Clark.  It seems my valiant, and manual, are an older version.  My apologies for the mis-information.

No, no, no... it's not a correction. We're both right and it depends on the version of Valiant. I struggled with some Valiant issues for a month because the original builder followed the construction steps exactly. As it turned out, the engineers at E.F.J. had a change of heart (several times) and a friend's factory built unit featured some important updates.

The only reason I suggested the pots version is from the title of the post, and I should clarify that the resistor number references suggest the earlier schematic version and not just a component number change. Technically, R22 became R62, a potentiometer for RF Bias only and R61 and R63 were added as a separate Mod Bias circuit.

Here's an example of "We should start doing it like this from now on...":

WZ8J:
Thanks Clark,
That's the info I needed. I should have pointed out that the build manual I have is for the earlier version which had the taps vs. the pots. Either way, the reader will learn from the exchanges. 8)

WZ8J:
Quote from: WA5VGO on December 10, 2017, 09:52:52 AM

Try swapping the two outer leads. That should move the wiper to a different place on the element.


I like this idea. Will give it a try and let you know if that worked.

Thanks!

N1BCG:
Quote from: WZ8J on December 10, 2017, 11:45:24 AM

I should have pointed out that the build manual I have is for the earlier version which had the taps vs. the pots. Either way, the reader will learn from the exchanges. 8)

Here's the later schematic showing the bias adjustment pots:

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