[TMC] VOX-3 question

[Chris Bolkan]

Hi John and all!
S Documents..........I had no idea. How cool are those?!?
Thanks! This is awesome!
Best regards,
Chris
KI7NXY

On Tue, Apr 12, 2022 at 1:49 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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