[Milsurplus] 618S

[Mike Morrow]

>The 618S1 was a crystal only radio, or at least that's all I know. the ARC-38 
>replaced the 618S

The Collins 618S-1 was used by the USAF, and usually a "U.S." and a USAF-style
contract/order number "AF 33(600) xxxxxx" will be found on the name plate.

The Collins AN/ARC-38 was not a replacement for the 618S-1.  The AN/ARC-38 was the
USN set that replaced the USN AN/ARC-25 (combo of the AN/ARR-15 and AN/ART-13).

The USAF did not use the AN/ARC-38 unless it just happened to be in an aircraft
that had formerly been a USN aircraft.  Similarly, the USN did not use the 618S-1.
One can not be said to be a replacement for the other.

There are a lot more RT-594/ARC-38A sets out there.  These are USB-capable units
which RCA modified from the original RT-311 units in the very early 1960s.
As Jack mentioned, RT-311/ARC-38 units were easily available ten years ago.  I
bought mine at the Fair Radio warehouse during Dayton Hamvention 2002, even
though it was no longer in the catalog.  It helps to be able to paw through the
unadvertised stock!  I like its "purity" over the "Frankenstein" RT-594 USB mod. 

There is a version of the 618S-1 called the 618S-1/MC that was both tunable and
USB capable.  The USAF T.O. number is 12R2-4-6-32, dated 31MAY62, by RCA!  So
this version appears to be a USAF close equivalent to the USN AN/ARC-38A, with
RCA USB modifications, and with at least one important difference:  Its control
box CPC-1 was much smaller than AN/ARC-38 and 38A controls (no channel memory
feature), plus it allowed DIRECT numerical frequency input (no code book needed
to set cryptic code wheels).  I don't know if these were modified older 618S-1
units.  It takes a lot of work to transform a crystal-controlled AM set to a
tunable USB set.  At least the RT-594/ARC-38A was built from an RT-311 unit that
was already tunable.

There isn't any version called the 618S1-4, but there is a 618S-4.  I'm not sure
how it differed from the 618S-1.

I missed another Collins goody that Fair sold for years, the RT-380/AR.  This
is the USAF version of the 18S-4.  It was part of the AN/ARC-59.

Mike / KK5F