[Milsurplus] BC-221-AK frequency spread question

[John Hutchins]

Pete
Yes please transmit the procedure.

After setting the  Trimmer on the high end of the band with the 
Corrector maxed out the low end beat note is off  the mark
at the low end with the Corrector set a minimum by 4.4  ticks.

Hutch


Pete Williams wrote:
> John... it maybe that the 'heterodyne ' trimmer may have to be adjusted to
> get zero beat correction at the  xtal checkpoints using the CORRECTOR
> capacitor... The prohibition on readjusting the oscillator trimmers as
> mentioned in the TM11-300 manual para 32e  was rescinded in February 1946.
> . I can scan/email the correction procedure if you need further info.
> Pete Williams VK3iz
>
> -----Original Message-----
> From: milsurplus-bounces at mailman.qth.net
> [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of John Hutchins
> Sent: Monday, December 29, 2008 3:42 AM
> To: milsurplus
> Subject: [Milsurplus] BC-221-AK frequency spread question
>
> All -
> First Seasons Greetings to all.
>
> Initial condition found the Low and High band did not match the 
> frequency setting book.  All the serial numbers match on the equipment 
> and the frequency setting book.  The over all frequency spread over the 
> bands had, shrunk, narrowed, pulled in a bit.  I took pictures to make 
> sure the wires and components were placed as close as possible to there 
> original positions.
>
> Finished rebuilding the Master oscillator re-checking Coils, Capacitors 
> and Resistor values. Replaced 3 of 4 resistors which were way out of 
> spec.  One resistor was still dead nuts 5K. Replaced resistors 14, 
> 15,19. All the CAPS were with in 5% tolerance.  Both the Low and High 
> band coils were within 5% of specified value on the schematic.  After 
> replacing the components, another story, the band spread out a bit but 
> not quite back the original positions with in range of the Corrector.  I 
> can get the top end in but the lower end of the band is off a bit, not 
> with in correctable range of the Corrector. 
> Low Coil spec 7.06 mH measured 7.00 mH
> High Coil spec 25.84uH measured 26.2uH
>
>
> Any ideas on what causing the band coverage to narrow? 
> Any ideas on getting the band with in the range of the corrector cap?
>
> I am going to remove the MO coils and re-check again the corrector plate 
> distances.
>
> Ideas greatly appreciated Thanks
> Hutch
>
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