[Milsurplus] ARR-41 Info...now 618S

[WA5CAB at cs.com]

Mike,

I don't really collect aircraft sets anymore and have only a passing 
acquaintance with Post-War sets.  However, I do have a Service Manual on 618S-1 and 
618S-4.  I was going to quote a paragraph on Model Differences but the short 
answer is that the difference between the two is the 250 KC I-F Amplifier in the 
618S-4 radio has squelch and Selcal.  According to the manual, all other units 
in both model radios are the same, aside from any production modifications 
which could show up in either model.

In a message dated 9/13/2006 12:17:04 PM Central Daylight Time, 
kk5f at earthlink.net writes: 
> I have a USAF-contract Collins 618S-1, and the USN's Collins RT-311/ARC-38 
> and RCA/Collins RT-594/ARC-38A units, and I am familiar with the gross 
> differences that exist between these three non-equivalent units.
> 
> However, I do *not* know the difference between the civilian models 618S-1 
> and 618S-4, nor do I know the significance of the "/MC" that appears at the 
> end of some 618S model numbers.
> 
> If I understand correctly, you are saying that the 618S-4 is the exact 
> civilian equivalent to the RT-311/ARC-38, complete with SMO.  If so, did it use a 
> control box that had direct frequency entry somewhat like the later 618T, or 
> did it use complex frequency-versus-code thumbwheels similar to the 
> C-1398/ARC-38?
> 
> 

Robert Downs - Houston
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