[Milsurplus] A Little on the ARC-2

[Mike Morrow]

David wrote:

>The AN/ARC-2 doesn't get the attention it deserves;
>it was a big techno-leap forward for a WWII rig.
>The WWII vet is the RT-91/ARC-2; the RT-298/ARC-2A
>is a post-war version with several circuit improvements.

I've always liked the AN/ARC-2 ever since I saw the Roy Pafenberg hack-up article on them in 73 Magazine, 43 years ago.  I finally got one from Fair Radio in 1975, when they were going for $50 plus considerable shipping charges.  I've owned several since.  I have an RT-298 and MT-431 and C-244A, which is just about the complete system if one assumes that there will be an interphone system to handle the audio connections and level adjustments.  But I've still got my first RT-91 too, which I last tried on the air with a 28 vdc power supply 27 years ago.

Thanks for the run down on the electrical differences between the ARC-2 and ARC-2A models.  Very nice summary of the internal alterations.  I have one of Robert's (WA5CAB) excellent manuals on this gear.  The manual covers both the ARC-2 and the ARC-2A and is highly recommended for anyone doing any work on this complex (for the era) set.

There is a cosmetic difference between the two models that can be seen on the front panel, aside from the RT-298's two fuse holders on the right side and the spare fuse box in the middle.  The RT-298 lacks the RT-91's meter switch which allowed the meter to be connected to an RF thermocouple (also not present on the RT-298) for RF amp indication.

I think that most RT-91 units got some of the superficial modifications which appeared on the RT-298.  Many RT-91 units have been modified to add the front panel fuse holders and spare fuses of the RT-298.  Also, some RT-91 units had the RF amp indication defeated and the meter switch removed, some had the RF amp indication defeated but the meter switch left in place, and some RT-91 units retained the RF amp function even though the front panel fuse mod had been performed.

The RT-298 also uses cheaper plastic tuning knobs with fixed handle, while the RT-91 units have a milled metal knob into which the tuning handle folds when not in use.  Frankly, to me the RT-91 looks like a better quality set.

These units don't seem to bring much on ebay.  Very surprising.  I recently got an excellent condition RT-298 for $300 (about equivalent to the $50 I paid for an RT-91 in 1975), and I was the only bidder.  This unit still had the vent filters and wrench, and all the internal wrenches and screwdrivers.

>To get the cover off the rig, you first must remove the
>round "air filter" vent covers.  If you have the "C" shaped
>spanner wrench on the back, that's its purpose.

The wrench is often missing, also the filter vent covers are often gone.  Some got lazy.

>It's a very cool set. 

I agree 100 percent.  It's likely the very best set of its type from late WWII.  Most appear to have had a long service.  I remember seeing the AN/ARC-2 still in service on USN TS-2A aircraft at NAS Corpus Christi in 1972.  I talked to one of the avionics techs about them, and he said they were a real pain when it came to getting replacement parts.  But I'm happy to be able to say I've flown on a couple of USN aircraft that carried the AN/ARC-2 (and a R-23/ARC-5 too).

73,
Mike / KK5F