[R-390] alignment assistance for an R-390A beginner

[Barry Hauser]

Greetings Antero and Welcome Aboard!

Also apologies to the List as I think I just hit the send button before
typing anything, so there will be one of those reply posts with no reply in
it.

>this is the first, but probably not the last time I write to you.

Well, I hope someone writes to the group -- it's been too quiet lately. ;-)

>I have just recently acquired an R-390A receiver from Fair Radio. Having my
background in >humanities (linguistics), I chose the "checked" option in
hope of a working unit.

That makes good sense.  Something to keep in mind about Fair Radio.  They
are true to their name.  This is a good time to look over the receiver
carefully for any missing or broken parts, just in case they missed
anything.  In particular, check for any broken shaft clamps, but also any
missing hardware, etc.  Make sure the receiver is truly working on all MC
bands.  If a few are not, it is probably a bad crystal.  Fair is good about
replacing any missing or defective parts and it is usually not necessary to
return a bad part to get replacements..

>After having paid almost another USD 550 for shipping, value added tax and
customs duties, I >finally have my radio on my desk here in my hometown of
Nurmijarvi, Finland. I think I got a >nice receiver: it has an engraved
front panel (without a manufacturer's tag), one fuse, the PTO is >a Collins,
power transformer from EAC, AF subchassis from Capehart... well, all in all,
a nice >example of the modular construction principle! These all are from
the 1960-1961, or >thereabouts, contracts.

Wow!  I suppose that was for air freight.  At some point you might want to
get a repro tag for the front panel depending on what the receiver mostly
is.  However, it seems it is the traditional "depot dog", so a generic tag
might be most appropriate.  They can be mailed in an envelope for about 80
cents US postage.

>I resisted the temptation to apply power to it before I had changed the
critical capacitors in the >IF subchassis (C-531, 547, 549, 553).

A good move.

>Obviously, I also had to make the necessary changes in >the power supply
for our 230 VAC. >Further, I have now changed all the capacitors in the AF
subchassis listed on KK4DF's >homepage.

Also good.

>At this point, the receiver is working surprisingly well, taken into
account the little work I have >done so far. Signals are present on all
bands, random checks into tube sockets show >approximately the correct
resistance and voltage values, and test point E607 provides exactly >150
VDC.  In fact, my R-390A receives just about every signal my other receiver,
a Drake >R8B, receives. Not bad, although I do notice that the Drake is more
sensitive on the medium >wave band, at least so far...

A small digression:  Now that you have an R-390A, with all its substantial
knobs, etc., the Drake's tuning knob may feel particularly cheesy
(cheap/light) by comparison, if you have not yet "upgraded" it.  This is
done by filling the hollows with something like steel balls and glue or by
substituting the tuning knob from an Icom R-72, which is available from Icom
as a replacement part.

>Of course, my R-390A probably has who knows how old tubes and it probably
is not perfectly >aligned, which brings me to, yes, alignment issues:

It would be good if you could acquire or borrow a good tube tester.  While
you can simply substitute known good tubes, some replacements require an
alignment.  It is also important to check replacement tubes for shorts
before using them.  A short in a tube can cause other damage.

>I can at the moment adjust the frequency display to indicate the correct
frequency as described >in the Operator's manual, but I notice that, using
the "zero adj", I end up at the very limit of the >KC knob's range of
movement without the last three digits of the display changing. More
>specifically, I can't move the KC knob to the right (higher frequencies).

>Further, the mechanical alignment at the frequency reading of 07+000 is
slightly off, with the cam >plates (all of them) better in place at
frequency reading 07 990. Now, in such a case, the manual >suggests the
remedy is to set the cam plates to their correct position, and then manually
change >the frequency reading to 07+000. In my case, then, I would have to
add 10 kHz to the reading. >But here's where my confusion already starts: if
I add 10 kHz to the frequency reading, I can't >correct that using the "zero
adj." as I'm already at the limit of its range. Further, the nice balance
>of approximately 35 kHz above and below a "XX 000" reading on the frequency
indicator will >be gone, right?

It seems that -- provided all the cams are lined up at 07 990 -- you might
simply adjust the reading of the counter with the gear on the counter shaft.
However, the +/- 35 kHz will be off at the ends of the 10-turn stops of the
KC shaft.  It would seem that you should be able to adjust for that with the
appropriate clamp on that shaft.  But first ....

Do you have the Bristol (spline) wrenches of the correct sizes?

>So, as you notice, I'm a bit confused as to what setting affects what other
settings and what the >correct order of doing things is. Is there a
procedure described somewhere that corrects the >frequency error, centers
the "zero adj." to the middle of its 15 kHz range, and restores the 35 >kHz
on both sides of a "XX 000" reading? Of course, what I'm after is a
non-techical >description using layman's terminology and definitely not
using signal generators, oscilloscopes >and other equipment that I don't
happen to own! I have downloaded TM 11-5820-358-10 and >-35, and the 21st
century technical reference, but can't seem to be able to extract the
>information I'm after.

The alignment procedures are all in the manuals, however they presume going
from start to finish, beginning with a full mechanical alignment.  There
isn't much in the way of isolated, individual "tweaking" instructions,
because the receiver is so complex mechanically, and so much is
interdependent.  The only way to assure that the receiver is running at peak
performance is to go through all the steps.

It seems as though you have been very thorough, however, it might be a good
idea to do some more checking.  For example, is the PTO fairly linear over
its range?  In other words, is the dial accuracy about the same at the low
and high ends of the bands?  Did you allow the receiver to warm up
completely?  Might take an hour or two for best results.  If you have not
already done so, "walk through" the full alignment as much as possible
without changing anything.

You can do some alignment just using the crystal calibrator, however, it
would be better to have a signal generator available.  A modest unit will be
good enough, however, for accuracy, a frequency counter should be used along
with it.  The small pocket-sized counters are sufficient.

Hopefully, someone else on the list can suggest a simple adjustment --
perhaps just the coupling on the PTO.  However, any quick fix may throw
something else off, even slightly off peak and you will not be getting
maximum performance.  Considering the investment you already have made, the
accuracy you seek and the fact that you are an R8B owner, I suspect you'll
be shopping for some test equipment very soon ;-).  I only spent one day in
Helsinki a few years ago on a Scandinavian cruise, and I do not remember too
much of what I saw through the tour bus window, so have no idea as to
availablilty.  Typically in the US, a suitable signal generator can be
purchased for under $100.  A new, small frequency counter typically sells
for under $75.  Radio Shack used to have one that went on sale for less than
that.  A signal generator with the built in accuracy required generally
costs more that the sum of the two.  You may be able to borrow these -- and
possibly borrow the guy that owns them.  I am sure there are sources in
Europe where the base price might be higher, but shipping and customs would
be less.  You don't need an oscilloscope.

Hope this helps.

Barry