[Hammarlund] SP600 receivers

[James A. (Andy) Moorer]

There are at least two: Both the JX-6 and the JX-26 were issued as R-274B at 
one time or another, the JX-6 being the earlier issues.

You can tell the JX-26 easily because the terminal strip E13 is a 
rectangular block (rather than a linear row of loop-terminals) and has 
screw-jumpers so that one wire may be easily switched between the N (Normal) 
and the DF (Direction-Finder) positions. The JX-6 has the linear row with no 
jumpers.

Plus, in both of these (and all other R-274 version SP-600 receivers), there 
will be four small screw holes in the front panel above the left 
frequency-readout bezel where the Signal Corps tag was.

Note that the later issues of both the R-274B and the R-274C were the same 
receiver (JX-26), so there is no way to distinguish them. At one time, there 
was probably a list of serial numbers that said which receiver went to who, 
but this list is lost in the backwash of time.

James A. (Andy) Moorer
www.jamminpower.com

----- Original Message ----- 

> How can I tell what series of SP600 is a R-274B/FRR.  Thanks
>
> J
> W7KSG