[R-390] Rack Mounted R-390A

[Robert Nickels]

dr7zyq wrote:
> Also, your message seems to suggest that you can bolt a '390/A into a 
> rack cabinet using the front mounting holes and let it hang in the 
> rack.  They are well built, but not intended for that.

Actually they are, as long as you aren't contemplating mobile 
operation.  From page 6 of  TM-11-856A 'Radio Receiver R-390A/URR' -

"Two cases and two rack-type cabinets (not supplied) are available for 
use with the receiver.  In addition, the receiver may be mounted in any 
standard 19-inch rack, if adequate ventilation is furnished.  In mobile 
installations, the weight of the receiver must be supported at the rear 
of the main frame rather than by the front panel alone".

The two cabinets are the light weight tabletop cabinet CY-917/URR and 
the more rugged CY-979/URR.  The manual later states that the 
"recommended cabinets have dowel pins that engage holes in at both rear 
lower corners of the receiver and provide the required support".

If hams were to install their R-390As per the procedures described in 
the TM, for Fixed Installations we would allow at least 1 3/4" (1 U) 
open rack space between receivers, and remove both top and  bottom dust 
covers  all  tube shields except those on V201 through V206, V505 and 
V701.  The  manual states that removal of these tube shields will lower 
bulb temperature of the tubes and prolong tube life, and that dust 
covers should only be left in place when extremely dirty or sandy 
conditions exist.  I suppose some hamshacks might qualify!

73, Bob W9RAN