[R-390] R390/URR and R390A/URR clamp screw torque

[jkharvie]

 Nice catch!Tighten larger Shaft Clamp screws within range of 8-10 inch pounds 
Tighten Smaller Shaft Clamp screws within range of 6-8 inch pounds

John 
N3JKE


    On Friday, July 24, 2026 at 04:30:28 PM EDT, Nick England via R-390 <r-390 at mailman.qth.net> wrote:   

 See notes 15 and 16 here for original spec
https://www.navy-radio.com/rcvrs/r390a/drawings/17310-07/07-28-SM-D-248975-TRAIN%20ASSY%20-%20GEAR.pdf



Nick England K4NYW
Chapel Hill NC
www.navy-radio.com

On Fri, Jul 24, 2026 at 3:57 PM Perry Sandeen via R-390 <
r-390 at mailman.qth.net> wrote:

> List,
> I was trained on the R390A in USAF tech school in 1963. There was no
> training or information given about clamp torque.
> However list member Glen Scott who has done total remand (including
> complete panel restoration) of the R390A for years as a living, posted on
> this list his experience.  It involved using a torque screwdriver and the
> value he found optimum for no slippage or clamp  breakage.
> I don't remember when it was posted so if someone would re-posit it, it
> should provide the necessary information needed.
> 73,
> Perry KM6FQV
>
>
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