[Milsurplus] RAF R1155 Wonders and Woopsies.

[David Stinson]

RAF: R1155 Wonders and Woopsies.

The R1155 project continues 10 mins here, an
hour there.  Work and life keep interfereing 
with the important stuff! :-)

Refurbishing the type 13 tuning mechanism.
There is a YouTube video that discusses this.
I recommend it.
https://www.youtube.com/watch?v=-n7fQcQDDJI

A couple of important notes:
Note that little knob "set screw" with the small post
that fixes the "fast tune" knob- once your unscrew
it enough to remove the knob, the screw is fully
dis-engaged from the threads!  If you turn the knob
upside-down, the screw will fall out, the
Screw-Gremlins will grab it and you can forget
ever, ever finding one like it.  Careful!
Also:  Getting this screw engaged in that hole again
is a booger-bear.  I think the bad rep of the type 13
tuning mech probably comes from struggling to 
get this blasted screw back in place.

I didn't use cardboard to replace the old cork
friction bed.  I used green hobby felt like you 
can find at any WallyWorld.
https://goo.gl/photos/TNpyySto3rH6Eda88

The "Star Spring:"  the YouTube fellow says his
was "sprung" to 3mm.  Mine was 1.2 mm and flexing
it to 3mm made it drag so hard that the "slow" knob
would turn the "fast" knob as well.  1.2 mm worked
for me.

There are three gimbles inside the "slow tuning" knob.
They get dirty.  I cleaned them with naptha (lighter fluid)
and put a drop of oil on each end.  Don't, don't drop 
them.  The screw gremlins lust after these.  They will
be gone and you will find them the same place as
that weird pig-tail knob set screw- Nowhere.

This is how mine came off- Note the gimbles are 
conical.  One of them was facing the wrong way,
which munged the tuning.  The small ends should
face inward.
https://goo.gl/photos/Wt5WACjqukAitg7E7

Had to adjust the "star spring" tension and 
place a drop of oil on the brass washer.
Now works smoothly and as it should.
If someone knows an easy way to re-engage
that stupid "screw with a tail," knob set screw,
please tell us.

Low B+ tests:
The minimum B+ needed to start the LO reliably
on all bands is about 100V.  If one can live with
a couple of small dead spots for the sake of preservation
(and I can), it will play well as low as 75-80V.

I've aligned the set and, for a wonder,
 had it playing on the bench for 2 hours 
without any parts changes and no "creeping current" 
rises.  All seems well.
https://goo.gl/photos/tGKUMy5tzjGUeua77
https://goo.gl/photos/fLxk4wh3HQFJHKqX9

But "too good to be true"  keeps tugging on 
my hair.  So I thought I'd unsolder at least a couple
of leads from the triple .1 bypass cans and test them.
I tried to unsolder a lead and the formerly nice and
supple rubber split and peeled back.
Red wire connected to the upper left at
 the "postage stamp" mica.
https://goo.gl/photos/ihKkFFCCPoyGpCLD6
I refuse to accept this kind of damage just to 
chase a "problem" that doesn't seem to exist.

I will make some resistance measurements and
tack some modern resistors across older ones
that have drifted high, but other than that I will
make no repairs unless there is a stage failure
and then only that stage.  

I'm debating whether to take the dial cover off
and clean the inside.  The plastic is good and
the dial itself is clean, but dismantling this might
lead to cracks or flakes.  I can live with a little
crud vs. inflicting damage.

Still much more to do.  I think I'm not going to 
be so lucky with the DF circuits; we'll see.
All the photos/videos so far are available at:
https://goo.gl/photos/2xzNu7dc46UakF7d8

My thanks again to the members of our great
community who have provided info, docs and 
wisdom that make a project like this possible.

GL OM DE Dave AB5S