[Milsurplus] BC-348R Oscillator Issue output Frequency is 0 for part of band 4 : 6 - 9.5 MC

[Mark K3MSB]

You can load down an oscillator real fast by a direct connection with a
probe.   I use this when adjusting oscillators....

[image: image.png]

.... attached to either a scope or frequency counter.    I have a few of
them with different loop sizes and number of loops.

73 Mark K3MSB

On Thu, Aug 21, 2025 at 11:24 PM hwhall--- via Milsurplus <
milsurplus at mailman.qth.net> wrote:

> That's an unusual approach to aligning the tuning.  Are you quite sure the
> freq counter isn't loading down the oscillator output & sometimes just
> killing it?
>
> Wayne
> WB4OGM
>
> On Thursday, August 21, 2025 at 05:47:35 PM MDT, jphutch60bj <
> jphutch60bj at gmail.com> wrote:
>
> Reading the Manual TO-12R2-3BC-112, Revised 15 April 1957,  Page 4-3
> paragraph 'e'.
>
> On the four lower frequency tuning bands the
> oscillator frequency is higher than the desired signal
> by the intermediate frequency. On the two higher
> frequency ranges, bands 5 and 6, the oscillator is on
> the low frequency side of the desired signal. The latter
> results in a more uniform tuning ratio over these
> bands and increases the image rejection ratio.
>
> Before I start doing Brain surgery on BC-348R by pulling the RF Units .....
>
> I was Checking Oscillator output frequency with a frequency counter,
> tweaking the outputs from the oscillator on each band.
>
> Band 4, frequency range of : 6 - 9.5 MC,  reading the manual the
> Oscillator High Side output should be between 6.915 - 10.415 MC  for band 4?
>
> My Oscillator goes dead no output,  between DIAL Frequency reading of:
> 7.2  to 8.8 MC - which equates to an Oscillator output frequency of
> "+.915"  should be between  8.115 - 9.715 MC.
>
> Issue the output Frequency goes to 0 as measured  on Pin 8, VT-91, 6J7.
>
> If the manual is not wrong,  why is the oscillator output dropping to 0,
> on this one band?
>
> It aint the tuning cap!-} , as there are no problems with other bands.
>
>
> Thanks for you thoughts in advance.
>
> JPHutch
>
>
>
>
>
>
>
>
>
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20250822/7152716b/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image.png
Type: image/png
Size: 172445 bytes
Desc: not available
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20250822/7152716b/attachment-0001.png>