[R-390] Autotuners

[Walter Wilson]

Thanks for all the discussion recently on the R-391 autotuner.  I spent 
some time this weekend and got mine working again.  Yeah!  The R-391 
autotuner may not be the most useful invention, but it sure is fun to watch.

I got mine about 1.5 years ago from Don Reaves (thanks Don).  It 
initially had a bad relay (K102) that I replaced with 2 newer relays, 
which fit in the same space.  There was also a small piece broken in the 
MC positioner, which I was able to make a replacement for from a similar 
piece of scrap metal.  I had trouble initially getting it synchronized, 
but finally got it today.  It's nice to have it working as it should.  
Now that the autotuner is working, I'll proceed with a decent 
restoration and alignment before it moves into one of the primary 
operating positions.

Again, thanks for all the discussion on this list.  You guys woke me up 
enough from my vacation to get me to "play radio."

Happy New Year to All,
Walter - KK4DF
http://www.r-390a.us

Drew Papanek wrote:

> Hello,
>
> Sandy Geiger expressed misgivings about firing up the autotune on his 
> Mish-restored R-391:
>
>> Guys-  I  have  an  R-391,  s/n  282,  that  I  got  from  Rick  Mish.
>> Electronically,  it is tweaked to the nines,as all Rick's restorations
>> are,  but  I've  never  been  brave-or  foolish-enuff  to  fire up the
>> Autotune.  Rick  kinda suggested it would be in my-& the radio's- best
>> interests  if  I  left  it  alone.  Too  many  tales  of R-391s eating
>> themselves have convinced me this is the right thing to do.-Sandy G.
>
>
> He cited Barry's observations:
>
>> It is impossible to walk this gizmo through manually in  steps, 
>> though you can put a bristol wrench in the synch >adjuster,  lock the 
>> knobs down and rotate it.  However,  it's not a complete simulation 
>> as the relay and control unit
>> aren't doing  their things. It's all hard-wired together -- including 
>> the relay -- no socket.
>
>
> I was able to manually operate the autotune and exercise the 
> electrical portion of an ART-13 by mechanically disconnecting the 
> motor from the rest of the autotune.  With power applied and channel 
> selected, the motor would run until I had turned the shaft (many 
> turns!) to operate the limit sensing switch, whereupon the relay would 
> pull in and the motor would reverse; running until I had turned the 
> shaft enough(the other direction) to operate the channel position 
> sensing switch (too lazy to go get the manual and see what they call 
> those switches).
>
> Yes, the slip clutches were frozen with gummed-up lubricant and I did 
> not force the movement.  Who knows what damage would have resulted had 
> I tested under motor power.  Disassembly, soaking in lacquer thinner, 
> relubrication and reassembly corrected the problem.
>
> I don't think I used a synthetic lubricant; the process will therefore 
> have to be repeated in another 20 years or so.
>
> There is a special tool for turning the ART-13 autotune line shaft; I 
> did not have the tool but it was a simple matter to make one up.
>
> It would be a simple matter to lower voltage to the motor to reduce 
> the torque for testing purposes (for the R-391, back on topic, whew!).
>
> I used an old Telco power supply salvaged from the junkheap for the 
> 24VDC - no construction required there.
>
> Drew
>
>
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