[Milsurplus] Re: HF radios in WV 121 Connies and C 97 tomb raiding

[Mike Morrow]

>....see the inside of the Chanute Air Museum's 
>WV 121 Super Constellation. It had a ... an ARR 41 rcvr and two 618T
>HF SSB xcvrs.

It almost sounds like this aircraft had been in U.S. Navy service, having an AN/ARR-41 HF receiver which was usually paired up with the USN's AN/ARC-38 or -38A HF set. 

The 618T sets installed were likely the 400 Hz-powered military version, the AN/ARC-94.  In a transitional period, larger USN aircraft frequently had both a new AN/ARC-94 set and an old AN/ARC-38A installed.  It would appear that in the aircraft you saw, another AN/ARC-94 replaced the AN/ARC-38A.

> What struck me as unusual is that the 618 T was paired with the coupler
> that I usually associate with the ARC 38, I think it was a CU 351 ...

The AN/ARC-38 and -38A coupler is the CU-351/AR (nearly a 180L-3).  The 618T sets like the AN/ARC-94 (618T-2) and the 28 vdc AN/ARC-102 (618T-3) used an almost identical coupler, the CU-991/AR (180L-2).  I have both, and the *only* differences I know of between the two are a different type of power/control connector on the front, and the CU-991/AR does not have an antenna switching relay like that found in the box projecting out of the front of the CU-351/AR (The antenna switching takes place in the RT unit for the AN/ARC-94 and -102, and in the CU unit for the AN/ARC-38 and -38A).  Both the CU-351 and CU-991 are limited to use below 25 MHz.

>... not the usual 490T that I see paired with the 618T.

The 490T (CU-1669/AR) was a later development replacing the CU-991.  It allowed use of the full frequency range of the 618T.  But even in the late 1960s, new aircraft like U.S. Army UH-1D/H helicopters still used the older CU-991 if they had an AN/ARC-102 HF set installed.

>Was this standard or is it an artifact of a cosmetic interior restoration?

It is undoubtedly 100 percent authentic.

> I have some photos I can email if anyone is interested. 

I'd be interested...I always enjoy seeing military aircraft radio installations.

The 618T has to be the single most popular and long lived aircraft HF set ever developed, for both civil and military applications.  It is a beautiful system.  I'm still looking for a mount/inverter for my RT-698/ARC-102.  All it takes beyond that for a complete system is the C-3940/ARC-94 control box and the CU-991 or CU-1669/AR.

73,
Mike / KK5F