[ARC5] ARA, SCR-274-N, AN/ARC-5 Remote Control Box Dials - Questions

[Mike Morrow]

Here is a table of IDs for those small dials that are designed to be
installed on the remote control boxes for the associated receivers:

  Dial MHz      RAT/RAT-1     ARA     SCR-274-N    AN/ARC-5
0.19 to 0.55       --        #6051     MC-212     ID-25/ARC-5
0.52 to 1.50       --        #6052     MC-415     ID-26/ARC-5 
1.50 to 3.00       --        #7575       --       ID-27/ARC-5
3.00 to 6.00       --        #6053     MC-213     ID-28/ARC-5
6.00 to 9.10       --        #6054     MC-214     ID-29/ARC-5
13.5 to 20.0     #6056         --        --           --
20.0 to 27.0     #6193         --        --           --

It appears that none of the dials were ever marked with any of the IDs
shown above.

There were NO such dials for the eight-receiver RAV because it has no
remote control boxes.  It was supplied for local control only.

These dials for the RAT/RAT-1, early ARA, and SCR-274-N have their
frequency scale and figures inscribed in small non-luminous characters
on a sharply-inclined dial surface that limited how large those
inscriptions could be.

In contrast, the equivalent dials for the AN/ARC-5 have a greater area
of dial slope that permitted the frequency scale and figures to be much
larger and luminous.  It was a significant improvement for those AN/ARC-5
installations that actually used remote receiver tuning boxes or panels.

The drawing/part numbers in the equipment manuals of both dial types for
a particular frequency range are identical, oddly enough.

I have tracked ARA control box auctions on ebay, and even seen a few ARA
boxes at hamfests.  Other than in an ARA/ATA manual, I have NEVER seen
an ARA control box that used those earlier style dials that became
standard for the SCR-274-N.  I had assumed that there was some program
that replaced the old style dials with the newer, more-legible, "ARC-5"
dials on in-service ARA gear.

However, I just obtained a NIB Stromberg-Carlson receiver control box 
CCT-23251 with dials as listed in the table above.  It was made under
contract NOs-96736, Feb. 5, 1942, and bears an ACCEPTED date of APR 1943.
This dates the control box about eight months before AN/ARC-5 equipment
began appearing in general issue.  It appears that the dials with the
improved legibilty first appeared with mid-era ARA sets, well before
the AN/ARC-5 sets, and that such dials were not some later backfit.

So, one question:  Has anyone ever come across an ARA control box that
still had original dials such as the SCR-274-N used throughout its
production?  If so, does provenance indicate that the dials weren't simply
transferred from an SCR-274-N box, or was there the dial that could NOT
have been taken from an SCR-274-N box (a 1.5 to 3.0 MC dial)?

My last question:  Several have reported coming across the SCR-274-N
MC-415 dial for .52 to 1.5 MC.  Was is an early style like others used
in the SCR-274-N, or was it the mid-ARA and AN/ARC-5 style of dial?

Mike / KK5F