[ARC5] R-26/ARC-5

[Mike Morrow]

>The small dial mounted to the tube cover underside is indeed for the
>remote tuning box.

The most common remote unit for receivers that are to be remote tuned
is the C-26/ARC-5 "box" or the C-125/ARC-5 "panel".

>The local knob was used by the tech to set the freq on the bench...

The local tuning key is the A.R.C. 9554.

>...and then returned to its tube cover mount...

The tuning key would *not* be returned to the storage base on the
tube cover.  Instead, the key would be reversed and screwed down 
over the front panel spline port to cover it.  (It keeps out dirt,
protects threads, and provides positive indication that nothing
should be connected.)

>...before the set was re-installed in the aircraft.

I suspect that it was more common to set the frequency of a lock-tuned
receiver while the unit was installed in the aircraft.  Each lock-tuned
receiver would have an associated transmitter on the same frequency
that would require adjustment in the aircraft, so there would not be much
time saved by pulling the receiver and tuning it on the bench.

>You can tell you have a lock-tuned set if there is a yellow circled 
>stamped above the tuning spline.

The other indication is the presence of the small white MC/DATES plate
below the tuning port.  These are found only on receivers designed
to be locked-tuned (R-25, 26, 27), and will not be found on R-23 or 24.

The only control available on the remote control boxes for a locked-tuned
receiver is sensitivity/volume (NO frequency, BFO, or power).  There is
a somewhat scarce single locked-tuned receiver control (C-27/ARC-5), but
the most common control box that was used with lock-tuned receivers is 
the C-38/ARC-5.  It has controls for the AN/ARR-2 homing receiver, plus
audio controls for the R-28 VHF receiver and up to two lock-tuned
MF/HF receivers.

Mike / KK5F