[Milsurplus] URM-25 Question

[Michael D. Harmon]

Hi Folks!

For years I had a URM-25B.  When I bought it back in the early 
Seventies, it had every accessory that they originally came with - TM, 
all the adapters, cables, etc.  I used that thing for years! About 10 
years ago, I decided to try to "modernize" the bench a little and phase 
out some of my hollow-state test gear.  I put out some feelers as to 
what the military had chosen back in "the day" to replace the millions 
of URM-25's that were out there.  The answer - the SG-1144/U.  This 
generator was built by AUL, and it looks like a twin of a Logimetrics 
sig gen, but it's not exactly the same unit.

The SG-1144/U covers 50 kHz to 80+ MHz, has AM and FM modulation as well 
as CW, and has an attenuator with -120 to +10 dBm output.  It also has 
100W reverse power protection on the RF output.  The primary negative 
about the unit is that the frequency display is derived off the VCO, 
rather than being a true output frequency measurement.  I removed the 
display and the two plug-in cards and installed one of the W3ZI counter 
units.  I sampled the RF output going to the attenuator and replaced the 
original display with the LCD panel attached to the W3ZI board.  I 
replaced the "Display Test" button with a mini pot used to adjust the 
LCD backlight/contrast. I'm very happy with results!

I would suggest that anyone interested in getting an SG-1144 go through 
the unit FIRST and replace the orange-dipped tantalum electrolytics with 
decent aluminum caps.  Those orange tantalums are notorious for going 
dead short (as any Cushman service monitor owner knows all too well)!  
Manuals are available online at http://radionerds.com/index.php/SG-1144.

I haven't seen of these units lately on E-Pay, but you mil-surp guys 
probably have connections that we mere mortals are not privy to!

Mike, WB0LDJ