[Milsurplus] Re: [ARC5] Curious what this originally went to

[Kenneth Corwin]

Hello, Everyone -

Gordon White and Dave Stinson are correct.

This special tuning knob (A.R.C. 18802; Dial, Control
MX-2871/ARN) was part of Electronic Equipment
Maintenance Kit MK-427/ARC.  The MK-427 was designed
to support the AN/ARC-60 and "certain components of
Radio Set ARC Type 12."

TM 11-6625-384-12 describes the application of the
MX-2871 tuning knob as used to position the tuning
capacitor of the R-508 (A.R.C. R-19) to its rf
alignment frequency, roughly as follows:

   a. Rotate the tuning knob counterclockwise until
the receiver's tuning capacitor reaches its stop.

   b. Remove the tuning knob without disturbing the
position of the receiver's tuning capacitor.

   c. Rotate the tuning knob until the red zero line
is in the uppermost position.

   d. Reinstall the tuning knob without disturbing the
position of the receiver's tuning capacitor, keeping
the red zero line in an uppermost position where you
can see it.

   e. Rotate the collar on the tuning knob until the
black fiducial mark on the collar is aligned with the
red zero line.

   f. Rotate the tuning knob 4-3/4 turns clockwise to
set the receiver's tuning capacitor to its alignment
frequency of 144 mc.

---

The R-508 (A.R.C. R-19) tunes from 118-148 mc.

The R-509 (A.R.C. R-15), the R-445 (A.R.C. R-13B), and
the A.R.C. R-32 use the same tuning capacitor (A.R.C.
11859) as does the R-508.  These receivers, however,
tune from 108-135 MC and have an rf alignment
frequency of 131 mc (also 4 mc below the top of their
band).  

Perhaps the same procedure could be used to set the
tuning capacitors of these receivers to their 
alignment frequency.  Almost none of A.R.C.'s Type  12
receivers had tuning dials.

Hope this helps.

73, Ken Corwin KF6NUR  Canyon Country, CA