[ARC5] Why is the ARC-5 Tx rack so hard to find?

[Mike Morrow]

> Weren't there as may ARC5 sets in use as SCR274? What's up with that?

It's pretty simple if one understands what service used what set, and which service operated the most aircraft.

The AN/ARC-5 is a Navy MF/HF/VHF command set that began introduction in mid-1943 in new USN  aircraft.  Earlier USN aircraft after 1941 requiring a MF/HF command set would likely have the original USN ARA/ATA set on which the USAAF SCR-274-N is based.

The WWII USAAF aircraft inventory and anticipated radio needs were much much greater than that of the USN.  Many SCR-274-N components were made in quantities well beyond 150,000 units.  It is doubtful that USN acquisition was even 20 percent of that, shared between the ARA/ATA and the AN/ARC-5.

All ATA transmitting components will work in a SCR-274-N system that is wired for low-z AF.  The ONLY electrical transmitting components of the ATA and SCR-274-N that will work in an AN/ARC-5 system are the dynamotor and the antenna relay.  AN/ARC-5 transmiiter components have ALWAYS been the most difficult to find.  Most of the connectors are unique...two in particular are much harder to find than the transmitter racks.

It takes a lot more time and money to assemble an AN/ARC-5 set than it does an SCR-274-N.  FWIW, for most of the same reasons, assembling an ARA/ATA set can be very challenging, but at least common SCR-274-N components can be substituted while awaiting the proper part.

Mike / KK5F