[ARC5] UK R1155 Receiver Gurus?

[David Stinson]

Working on a U.K. R1155N receiver,
sent by a generous and kind gentleman
I am privileged to know. Got it playing,
but it needs a careful alignment.

I can find only partial manuals and some
schematics on the web, none of which
cover the alignment procedures.

The IFs need tweeking, but the cans have
holes in the sides through which one can
see iron cores, but they do not appear to
have slots or key holes one could use to
align them. The IFs, normally 560KC,
  were mis-tuned to 566KC.  For now, I aligned
the BFO accordingly.  Anyone have the procedure
or experience aligning these IFs?

I have not attempted to align the RF circuits
without the proper information.  Also, the
coil slugs are varnished into place.  Someone
already broke one trying to "gorilla" the
varnish.  Has anyone found a solvent which
will not harm the coils?

I have been known to accept moderately degraded
performance as a "fair exchange" to prevent damage.
I could live with the set as-is (I'm not using
it for DXCC afterall), rather than break things.
It plays and sounds decent.  My "A" model has
  somewhat better audio, but there may be
issues in the audio output as yet undiscovered.

The "A" model has run well for years with
regulated 135V B+.  The power supply is built
into the speaker enclosure and includes
a sand-state audio amp to drive the speaker,
since the R1155 is designed for headphones.

The power supply transformer is a toroidal
as used in many "ac inverter" circuits.
It has dual 115 VAC windings and dual 12VAC
windings.  One 115 winding is used as a primary
and the other is bridge-rectified for B+,
being about 180 V unloaded. This is fed to
an NTE1743 HV regulator providing 135V B+
with *Floating B-* like a BC-348.  The
regulated B+ makes the rig quite stable-
not as good as a refurbed and B+ regulated
TCS receiver, but close.
I will likely build a duplicate supply/amp into
the speaker for this set as well.

One of the 12 VAC windings is bridge-rectified
and fed to a small DC-DC buck converter with
provides 9 VDC to the speaker amp.  I could have
done that for the filaments using the other 12V
winding but I had already mounted a separate 6.3 VAC
transformer for filaments before I thought of it.

So- Who knows how to align these IFs and who
knows how to dissolve the varnish on the
RF coil cores?

Also- Both this "N" model and the "A" model
seem to suffer from images.  Anyone
else see that?

If you happen to work on an "N" model some day,
note that when you are using the two lowest bands,
the set gets antenna connection from pin 2,
"Trailing Aerial."  When on the higher bands,
it connects to pin 1, "Fixed Aerial."
You can jumper these two in the connector
if using one antenna.

N Model playing (short):
https://photos.app.goo.gl/zMDvVrLWyF9ebvJi7

TNX OM ES 73 DE Dave AB5S

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