[R-390] R-390A /CV-157 /CV-591.

[Flowertime01 at wmconnect.com]

John,

You ask if anyone here suggest a way to find a CV-157 , or a CV-591 cabinet.

The R390 and R390A mostly did not come in a table top cabinet like the ones 
you refer to. Mostly we were mounting them two or more in upright racks or side 
by side in a sloped front double wide cabinet. 

The receiver has a standard 10 1/2 inch 6U high front panel. A "U" being 1 
3/4 inches. I have no idea who standardized the U at 1.75 inches. and decided 
things should be in multiples of that unit.

Blank panels come in 1.75 high increments. And they are all 19" wide. 24" is 
also another standard width. 

Finding a table top cabinet that is deep enough can be a problem.

HP put some signal generators in some standard cabinets with RETMA mountings.
RETMA being the standard hole pattern that goes with the U panel heights. 

Once you under stand there is a method and pattern behind the madness you see 
the logic in the hole patterns along the sides of most military and heavy 
duty test equipment. Lots of it comes out of the little cabinets and get mounted 
in big racks in the shops and labs where it lives forever.

You can find short "table top" cabinets around. Watch your local swap meets. 
If you live near a big military contractor, watch for their surplus sales. 
These guy will some time put stuff out for sale. Hughes use to do employee 
preference sales on the first Saturday of the month in Fullerton California. Boeing 
did sales in Washington. Rockwell did sales in Los Angles.

Any way there are commercial cabinets available as used equipment. If you 
find one a bit more than 6 U high, you can put the receiver in it and fill in the 
extra space with a blank panel of 1, 2, 3 or more U high.

Cabinets are listed new in catalogs but the price exceeds the price you pay 
for the radio. Shop around until you hit the $40.00 range for a good looking 
used short rack.
Full "6 - 8 foot cabinets closed on sides with a back door can be had for $80 
- $100 dollars. You can also find short 4 foot floor racks. some on casters. 
Lots of these were old computer cabinets and are floating around.

The rail pattern is a standard pattern in all these cabinets. Any of them 
with a rail set 19" wide will work. Some have threaded rails for 10 x 32 bolts. 
some have holes and use a tinner nut (cheep "yea cheep" not the cheap) nuts or 
a good nut with a retainer clip that go with the rails. There are also "nut 
bars" which are strips of metal with 2 or 4 tapped holes that fit the RETMA rail 
pattern. Any of this hardware will work.

Try not to hang your R390 by the front panel. The receiver weight is to much 
for the front panel to support. The panel bends and will not look so good. 
Just because you can do it does not imply you should do it. The cabinet should 
have some blocks put in the bottom to support the receiver. Some table top 
cabinets will have internal rails to support the receiver. Floor racks typically 
have a set of rail holes inside to mount rails on that support stuff bolted to 
the front panel. These side holes and rails are also a standard type item. The 
rails are usually a 2 inch by 2 inch chunk of angle iron. In floor racks the 
back rail set is adjustable to fit slides and mounting rails. For being a 
standard item the stuff I have seen inside floor cabinet has ranged all over the 
spectrum. But it will all bolt up a lot like an erector set.

I hope this opens up your search window and you find a nice cabinet for your 
receiver.

You would like to have your receiver in a cabinet. If you wind up with a 
floor cabinet someday, remember you want to keep it enclosed and grounded. The 
whole idea of using a steel cabinet with an R390 on a table top is to shield it. 
Shield also implies ground. The R390's (and A's) will pick up a lot of local 
signal that mixes to noise in the audio output. Placing your receiver in a 
cabinet helps. Consider that at 30 Mhz a 1/4 wave is still several feet long. So 
small slots are still effective shields. If the AM band 1/4 wave is very long, 
an open cabinet side is not a shield. There is some rational between slots and 
screens being OK in shields and real big openings being not so good.

Roger KC6TRU