[Milsurplus] Fair radio

[Mike Morrow]

Scott wrote:

>The 618S-1 = RT-311

Er...that's perpetuating the error that the Collins 618S-1 and the USN RT-311/ARC-38 are the same.  They are not.   I have both the 618S-1 (military contract) and the RT-311.  Externally they look almost identical.  Internally most of the modules are the same.  But the 618S-1 is crystal controlled.  The RT-311 has the stabilized master oscillator instead of the crystal bank assembly as the principal difference.  But because of this, the 618S and the RT-311 and related support components are in no way equivalent or interchangable with each other.

>It seems that most USAF installations used the 180-L3 couple, whereas the
>USN installations used the CU-351, which has a MS power connector, rather
>that the legacy K connector that dates back to the 18S installations. 

This makes sense, because the USN's AN/ARC-38 is NOT part of the commercial 618S series.  It has its own CU-351/AR coupler (using the same type of connector as is used through the AN/ARC-38 system), while the commercial 618S uses the commercial 180L coupler.  It would be really unexpected to find the 180L used with the RT-311, or the CU-351 used with the 618S.  In addition, the RT-311 was developed after the 618S.

There's also a military version of the 180L-2 coupler, the CU-991/AR.  This was used with many AN/ARC-94 (618T-2) and AN/ARC-102 (618T-3) installations on into the 1970s, even though it had a 25 mc upper frequency limit.   I have one for the AN/ARC-102 that I'm trying to assemble.

73,
Mike / KK5F