[Milsurplus] ARN-6 vs. 7

[Mike Morrow]

>Did the ARN-6 replace the ARN-7? Was the 6 a better or newer design?

Yes to all questions.  

The R-5/ARN-7 was essentially simply the older BC-433-G (SCR-269-G) ADF
with a fourth band added for 100 to 200 kHz, plus a switch on the C-4/ARN-7
control box for MCW-CW selection.  It required both 12/24 vdc and 120 vac
400 Hz power.  It came out in late WWII.

The R-101/ARN-6 is a post-WWII ADF, used by all services, that required
ONLY 28 vdc for power.  It covers the same frequencies, is a little smaller
and lighter, and the loop is much smaller.

BTW, the JAN component number, rather than the JAN system number, is
USUALLY (but not always) the best indicator of the order in which a
component was developed/deployed.  Hence, the R-101 was later than the R-5.

>When were the last ARN-6 systems in use?

The TS-2A training aircraft at NAS Corpus Christi still had the AN/ARN-6
in the early 1970s.  It is quite a good ADF in aircraft that can support
the weight, so it wouldn't surprise me if there aren't AN/ARN-6 sets still
flying in some remote parts of the world.

>...the ARN-59 series receivers, maybe something with seven and nine pin tubes.

That was early Vietnam era, used a lot by the US Army and Air Force likely
well into the 1980s in older aircraft.  It uses pencil-subminiature  
wire-in tubes.  The all solid-state Collins AN/ARN-83 started replacing the
AN/ARN-59 by the mid-1960s.

>Looking for the ADF system to go with my ARC-38, ARC-55 and ARC-73
>system and cannot imagine it would be an ARN-6, that would be the
>only radio with octals.

Imagine differently!  The AN/ARN-6 is without ANY uncertainty THE ADF that
would most likely have been installed on aircraft with the sets you list.
If you had listed only the AN/ARC-73, which is the most modern set in your
list, then I would have say to choose the AN/ARN-59.

The AN/ARC-38 is USN (not USAF), while the AN/ARC-55 and -73 were predominantly
used by Army and Air Force.  I never saw an AN/ARC-55 or -73 in naval service.
The USN used instead the pressurized equivalent, the AN/ARC-27.  The USN seems
not to have installed a lot of VHF-AM command gear in their aircraft, the way
that the Army and Air Force did.

Of course, any AN/ARC-38 installation should also have the AN/ARR-41 auxilliary
receiver installed.

Mike / KK5F