[Boatanchors] Hammarlund receiver

[James A. (Andy) Moorer]

Unfortunately, more than one Hammarlund contract got the Signal Corps R-274B 
tag. Indeed, the early ones were SP-600JX-6 receivers. That designation 
(R-274B) was used on receivers as recent as the SP-600JX-26. Thre may be 
some models in between that went by R-274B as well.

The only way to tell a JX-6 for sure is to look at the wiring. It has four 
distinguishing features - first is that there are no large (25W) power 
resistors bolted to the side of the chassis over by the power entry 
connector. Second, there is no connection on the power strip E17 on pins 1 
and 3 (this shows that the AGC voltage is not fed to the gate tube). Third, 
if you take the cap off the transformer T1 housing and count the wires going 
to the RF deck, you will find 6 wires, not 7. If you want a fifth 
distinguishing feature, you can look at E13 - on the JX-6, it is a strip and 
not a square block.

If it does have stuff connected to E17-1 and E17-3, and it does have the big 
power resistors, and E13 is a block instead of a strip, it may well be a 
JX-26, which also had the R-274B tag on it.

Hope this helps.

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


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

> Can anyone on the net tell me if a Hammarlud Sp600JX-6 is the same as one
> havin the number R274B/FRR on the nametag on the receiver.
> Dave K4nwt