[R-390] Non-A alignment question

[Paul Staupe]

After several days of running down clues, I'm listening to jazz on the R-390
right now after all your help, and some phone conversations with Don
Heywood.

Long story short, it appears as though someone tuned it past the high band
stop, and the PTO was completely off.  I noticed that there was a red band
between the MC and KC which should have alerted me to the problem, but I
just thought that the display was different.  I had never a pure red band
before.

I took the RF deck out of the radio, and thanks to Don's help, I was able to
see that the cams in the rear aligned up, but in a completely different spot
than they were supposed to in the manual.

However, once I saw that the cams were lining up, it was only a matter of
time....

I went though the alignment process this afternoon, and was successful in
the 455 kc alignment steps, but I was less successful with the 2nd IF and
totally stymied by the first IF procedure.  I then tried to pump a 1500 kc
signal directly into the balanced antenna input, but really wasn't getting
anywhere, so I brought it back upstairs to plug into my 160M dipole which
should have melted the front end with BCB RF.. but nothing.

Then, I brought up the counter and attached it directly to the PTO output.
At the top stop "931" the readout was 2.2096 and I discovered a bottom stop
at -869 which was 3.221  The normal PTO output is 3.455 kc at the low end of
the band and 2.455 kc at the high end of the KC band (10 turns)

Out came the Bristol wrench, and I hand turned the PTO until I was getting
3.455 at "000."  Sure enough, I was getting a het with the BFO on a local
BCB powerhouse at 1330 kc, and knowing that I had my 2nd IF tuning way out
of whack, I started dropping the slugs back down, and the radio came to
life!

Tomorrow, I'll go though a proper alignment, since it is completely hot at
1500 kc and above, but pretty deaf at the low end which would be expected
since I tuned it up at the top end without test equipment to do the same at
the low end of each band .

Thanks so much for all your help.

Best regards,

Paul W0AD



On Wed, Feb 23, 2011 at 10:13 AM, Shoppa, Tim <tshoppa at wmata.com> wrote:

> Severely out-of-whack PTO, as in broken wire or cracked capacitor or maybe
> just a loose shaft clamp between main tuning knob/Oldham coupler/PTO?
>
> The original R-390 docs don't reference a frequency counter because that
> was only a gleam in anyone's eye at the time, but it's a very handy tool for
> 2011 :-).
>
> -----Original Message-----
> From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
> On Behalf Of Paul Staupe
> Sent: Wednesday, February 23, 2011 11:05 AM
> To: r-390 at mailman.qth.net
> Subject: [R-390] Non-A alignment question
>
> I recently got a R-390/URR (non-A) that was working properly when it was
> put
> in storage about 20 years ago.  When I received it, there was audio hiss,
> but no stations received.  I tried tuning it up using the manual with my
> URM-25D and a VTVM on the diode load to no avail.  I finally gave up and
> tried to peak a 1500 kc signal directly to the unbalanced input.  What I
> got
> was a band of BCB stations that was received about 630 kc higher than
> indicated on the Veeder Root counter... eg. WHO, Des Moines at 1040 would
> be
> received at 1670 kc, WLOL on 1330 would be at 1975 etc...
>
> Does anybody have any suggestions as to what this could be?
>
> Thanks,
>
> Paul W0AD
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