[TMC] VOX-3 question

[Nick England]

Yep - I figured there was an S but I couldn't remember where they were
squirreled away.
See page & of S-110 for RF section alignment....
https://tmchistory.org/tmc_drawings/drawings_db/s/s-docs_100_199/s_110.pdf

Have fun, Chris.....
Nick England K4NYW
www.navy-radio.com


On Tue, Apr 12, 2022 at 4:50 PM John Poulton <jp at cs.unc.edu> wrote:

> I haven't had time to research this, but it's possible that one of the
> S-documents (Specifications, located under "S" in the Drawings part of
> tmchistory.org) may include a document that outlines the factory procedure
> for VOX alignment.  They exist for some TMC products, but not all...
>
> And, I'm assuming you guys already checked the various manuals for the
> VOX..
>
> Sorry not to be more help!  This week has turned into a bit of a nightmare,
> time-wise.
>
> 73, John K4OZY
>
>
>
> On Tue, Apr 12, 2022 at 11:38 AM Chris Bolkan <bolkyboats at gmail.com>
> wrote:
>
> > Hi Meir!
> > Thank you for that restoration link. I completely missed that. There is
> > so much on John's site! I will check it out.
> > It is unfortunate that the frequency multipliers have no calibration
> > procedure. I'm not as troubled about fiddling with the multipliers as I
> am
> > by further messing up the tracking and endpoints of the master
> oscillator.
> > Best regards,
> > Chris
> >
> > On Tue, Apr 12, 2022 at 4:19 AM Meir Ben-Dror WF2U <wf2u at ws19ops.com>
> > wrote:
> >
> > > Chris,
> > >
> > > The only procedure for disassembling and repairing/calibrating the MO
> is
> > > in the link
> > >
> > >
> >
> https://www.tmchistory.org/tmc_restoration/paul_spivak_docs/gpt_750_mo_repair.htm
> > > .
> > > The GPT-750 MO is identical to that of the VOX and PMO series master
> > > oscillators.
> > > In the procedure covered there is no mention of how to align the
> > > multiplier/output stages.
> > >
> > > Good luck with the VOX-3.
> > >
> > > 73, Meir WF2U
> > > Landrum, SC
> > >
> > > On Apr 11, 2022, at 7:27 PM, Chris Bolkan <bolkyboats at gmail.com>
> wrote:
> > >>
> > >> Hi TMC lovers!
> > >>
> > >> I now have the VOX-3 back together and working. Everything seems to
> > >> function more or less. The master oscillator works very well putting
> > out a
> > >> nice sinewave throughout its frequency range.
> > >>
> > >> Unfortunately, I lost track of the exact relationship of the tuning
> > shaft
> > >> to the counter dial, and of exactly where within the almost inch
> travel
> > of
> > >> the calibration slug, the movement limits are established by the
> control
> > >> mechanism for it.
> > >>
> > >> So, even though I set the counter dial to be correct at 3Mhz, it is
> off
> > a
> > >> bit at each end and I am not sure if placing the calibration slug in
> > >> another segment of its travel will help.
> > >>
> > >> I did not mess with the fancy eccentric calibration tracking mechanism
> > >> built into the master oscillator capacitor. All I did there was
> > carefully
> > >> clean and lube everything so it all worked again. I think if there
> was a
> > >> way to calibrate the end points, it might be pretty close in the
> middle,
> > >> but I am not sure.
> > >>
> > >> The other thing that doesn't seem exactly right are the frequency
> > >> multipliers. They all work...sort of.....with reduced amplitude and a
> > funky
> > >> relationship to the output control, where the output control "peaks"
> the
> > >> output rather than just acting like a level control. The output
> > waveforms
> > >> are not super clean either with differing amplitudes over many cycles
> > >> probably indicating they need to be tuned up.
> > >>
> > >> I am only starting to dive into this, but thought I would ask if
> anyone
> > is
> > >> aware of a factory calibration or setup procedure for the VOX when it
> > was
> > >> originally being built. I think if one exists it would be very useful
> to
> > >> me. The VOX-5 manual I have is very helpful but does not dive into the
> > >> areas I took this thing apart so does not provide what I am looking
> for
> > >> unless I have somehow overlooked it.
> > >>
> > >> Thanks in advance if you can point me in the right direction!
> > >>
> > >> Best regards,
> > >>
> > >> Chris Bolkan
> > >> KI7NXY
> > >> ------------------------------
> > >>
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