[R-390] DA-121/U Dummy Antenna

[eldim at att.net]

Hello David & Fellow BA'ers,
If memory serves me correctly, I believe that the DA-121/U was the Dummy Load that was supplied with the military AN/URM-25, AN/URM-26 Series Signal Generators.  It may have been a supplied accessory with one or both signal generators. Hard to believe that it has been over 30 years since I last used on of these.  I just looked at my FEDLOG and it was still lasted as of Mar 05, with two part numbers.  The DA121U and  ENTRON INDUSTRIES LP, FOREST HILLS, N.Y.  Part Nr. 157C4.  National Stock Number 5985-00-557-5717; Last procurement shown is 12/86 at $169.58.  The DA-121/U is a 50 Ohms, 0.5 Watt, 0-50Mhz Dummy Load.  I recall that the URM-25 had four or five different types of attenuators and a Dummy Antenna Load in the lid.  These were a small rectangular aluminum box with a cover secured by 4 screws.  Each one had a BNC Input and Output Connector,  with the exception of one that had a BNC Input, and a Black and a Red Wire with alligator clips for the Output. I also think that I hmay
 have seen these in a tubular metal configuration, but don't hold me to that.  The TM, T.O. or NAVSHIPS Manual on these generators had pictures and electrical diagrams.  I'll bet if you go over to BAMA you may find the info that you are looking for.  Good Luck.
73,
Glen Galati, KA7BOJ
Tacoma,. WA
eldim at att.net

-------------- Original message from "David C. Hallam" <dhallam at rapidsys.com>: -------------- 


> Searching through the archives for information about the DA-121/U dummy used 
> to connect the SG to the R-390 balanced antenna terminal, I found a 
> reference that indicated it was constructed with approximately 100 ohm in 
> series with the load and 60 ohm in parallel. Is this accurate information? 
> I want to build one. 
> 
> David 
> KC2JD 
> 
> 
> 
> 
> 
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