[Milsurplus] [ARC5] BC-221 Silly Question

[J. Forster]

Let me see if I understand.

On the upper band:  You are able to get the dial setting in the book to
zero beat with the crystal, as per the instructions, at the lowest and
highest points called out in the Cal Book, by using the Corrector

On the Lower band:  You are able to get the high end to zero beat with the
Corrector, but not the low end, and suspect it's due to the cracked wax?
So you recalculated the tables, using Excel?

If so, that's exactly the same issue as I have.

I can adjust the Corrector to zero-beat at the highest cal point, but the
main dial has to be about 40 points below thye nominal setting to zero
beat at the 2 MHz end.

Since the lowest dial reading is the highest value of the main capacitor,
it behaves as if the low-band coil inductance in my unit has decreased
slightly.

Frankly, I don't see how wax cracking could alter the coil inductance. I
suspect the thermal balancer might have moved or something similar.

Best,

-John

================





> John, Group -
>
> I have read these articles or manuals on the BC-221:
> TM11-300
> QST1965 01 09
> QST1965 05 28
>
> Made an Xcell -LS spread sheets to re-calibrate one of the BC-221-AK's
> that I have.  Added in Equations for a best fit line to the Xcell Spread
> sheet.
>
> Noted in the spread sheet:   On High band, set to 3666.665, Align
> Crystal Calibrator  @68 DegF or 20 Deg C.  That is 3666.70, X 3 High
> Variable Oscillator Harmonic  and  X 11 harmonic of the 1000.00 crystal
> Oscillator.  No mention of CASE  (ON or OFF)?  Did not add a reference
> of where the data came from.  Also documented the slow slide of the
> Crystal Oscillator frequency to Case internal temperatures for measured
> over 195 minutes.
>
> The Wax coating was cracked on the Low band and the settings were not
> correctable per the manual.
> I did the realignment and the produced a chart which allows the
> corrector to operate properly now for the Low band and High bands.
>
> Now if I had the skill to duplicate the format and print a new settings
> book that would be great.  Hmmm....
>
> In use,  a terminated line to feed a frequency Counter, which taps off
> the Antenna output typically through a gimmick capacitor.
>
> Hutch
>
>