[R-390] PTO extender cable

[Barry]

Thanks for all the suggestions.  Yesterday, I took my working R390A, turned
it upside-down, and was able to confirm the "new" PTO is working.  I was
able to do the endpoint adjustment with this setup, but I'm figuring if I
want to tear into it to do linearity adjustments, I'd probably need a bit
more flexibility in the cable.

If the 100kc points are close, I won't have to mess with it.  I know my
Motorola isn't completely linear, but not more than 3 or 4 kc over the
entire range.  Maybe one day I'll get up the gumption to do it too.

As for the Z702 tool, I guess I'll just "roll my  own."

Thanks,

Barry - N4BUQ

----- Original Message ----- 
From: <Flowertime01 at wmconnect.com>
To: <R-390 at mailman.qth.net>
Sent: Monday, April 04, 2005 12:35 PM
Subject: Re: [R-390] PTO extender cable


> In a message dated 4/4/05 10:17:27 AM Eastern Daylight Time, n4buq at aol.com
> writes:
>
> Anyone have a source for connectors to make some extension cables for the
> PTO?  I want to do some linearity checks and would like to do it outside
the
> frame on the bench.
>
> Thanks,
>
> Barry - N4BUQ
> -------------
> Barry
>
> Thousands of old ASA 33's worked on these R390 and R390/A for years all
over
> the world for years and never even seen an extender cable. Not one Nota.
Old
> school knowledge was the extender cables introduced more problems in
feedback,
> loss of shielding, flaky connections than was gained by the extra working
> space.
>
> Stand the receiver on it end. Use a 2x4 to level the back of the receiver
> with its front panel. Pull the PTO connector bracket loose from the
chassis so
> you have some wire harness freedom. It is still a short leash. Set the PTO
on a
> small cardboard box so it does not have to hang on its wire harness.
>
> This setup was used to set the 10 turn end point adjustment.
>
> If you just need to run the liner deviation, pull the Standard BNC to Mini
> BNC adapter off the 455 output on the rear panel and use it on the end of
the
> R390/A PTO. The R390 is a bit more creative as it has the B+ on the coax.
You
> need to isolate the frequency counter from the B+ on the R390. Leave the
PTO in
> place and use the dial read out to count PTO shaft turns. Set one end at
455
> and zero the dial. Start rolling off turns. At each 100 on the dial
counter
> record the frequency counter reading.
>
> Just hanging the PTO out the up ended receiver and using a pencil mark to
> index to, we would get the end points to within 10 cycles or so.
Considering the
> counters and power company (Viet Nam, Korea, 69-75) we knew we were
kidding
> out selves with those numbers. But you can do it.
>
> If you were really going to go into a PTO and try to adjust the bank of
> little shins all stacked up along the PTO guide assembly, spring for the
connectors
> from Fair for the PTO harness. You likely have the coax BNC adapter and
can
> extend that cable to the counter with no problem.
>
> I have seen PTO that would not make end point spread and needed work. I
have
> not seen one that was considered so non linear as to warrant an adjustment
of
> the shin stack.
>
> However, these items are much older now and who knows what would do them
some
> good.
>
> Good Luck with this
>
> Roger KC6TRU
>
>
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