[R-390] Suggested Test Equipment for R-390A Alignment ??

[Gregory W. Moore]

Well, Terry,
    Call me old-fashioned if you will, but I can't recommend anything 
better than the AN/URM-25. I own a 1960's vintage RCA WR-50B sig 
generator, and a General Instrument 1310?? (the nomenclature number is 
partially obliterated on the front panel) Audio generator. I also happen 
to be partial to Boatanchor test equipment for Boatanchors, such as 
using my trusted Simpson 260 meter, instead of a state of the art 
digital meter for measurement, because, in all probability, that was 
probably used in determining the resistance and voltage figures to begin 
with, when the manuals were first written.

    There is such a thing as "how much precision is enough", and , since 
the R-390 was originally manufactured and tested with analog equipment, 
that is what the measurements were determined with. If one were to use 
one's modern digital meter, one can fall into tthe trap of "decimal 
madness" and take the precision way too far. Basically, there is no real 
need to look at all the decimal places when working on this equipment.

    The same goes for a signal generator. The URM-25 is robust, rugged, 
complete with accessories, has built in modulation sources, and, like 
all tube equipment, rarely fails. I realize that some of my loyalty 
comes from having used this (the URM-25) and other such equipment in the 
Navy "back in the day", and finding it absolutely reliable, but that is 
the truth. It is reliable, and again, is what the manual, and most 
likely the manufacturers calibration and test department used when the 
390's were shiny and new.
 < rant>< venting>
    I also carry this same theme through my other test equipment. My 
scope is "hollow state",  I have an L/C/R bridge which is also "hollow 
state" and a frequency counter similarly "hollow state. Although I have 
a full stable of up to date, state of the art, whoop-de-do computerized 
equipment, I still enjoy using the older equipment because, frankly, I 
enjoy using it, and enjoy the sights, sounds, and smells from "hot 
vacuum" and the deposits of many years of cigarette tar on various 
items. Although I no longer smoke, it brings back memories of far better 
times, when one was allowed to indulge ones pleasure without shrilly 
screaming soccer moms telling me what I should and shouldn't do. I also 
enjoy remembering the era when we did, actually, have a manufacturing 
base here in the good old US of A, and electronics people were a sought 
after commodity.
 < /rant> < /venting> (Big Evil Grin)

All the above being said, I can't think of a better signal source than 
the URM-25. Like the "Energizer Bunny (TM), it just keeps on going and 
going. The frequency range covers EVERYTHING  in LF-MF-HF communications 
which I am liable to run into in the natural course of things. If one 
carries out proper maintenance, and uses deoxit, etc. etc,  one doesn't 
have any problems.

73 es tnx de Greg Moore WA3IVX, etc etc, etc.



tburr@dixie-net.com wrote:

>Can anyone suggest/recommend a good basic list of "test" equipment to
>check the operation of the R-390A.  Is the AN/URM-25 absolutely a must -
>or can anyone recommend a specific substitute type signal generator ?  I
>have 2 R-390A's in storage that were operational years ago, and want to
>get them out put them to use ("If my back does not give out on me").  I
>plan to be asking a lot of "stupid" questions in the future, so please do
>not be too harsh on me.  I am not a tech, but I am sincerely interested in
>learning about the R-390A.
>
>Terry.
>
>
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>  
>

-- 
"All that is necessary for the triumph of evil is that good men do nothing."
                                                   --Edmund Burke

Greg Moore NNN0BVN PA
U.S. Navy-Marine Corps Military Affiliate Radio System (MARS)
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