[R-390] RF geartrain screws

[Roger Ruszkowski]

Chris,

The same bolts will work fine in the R390. The total part count may be different.

13 a bakers dozen would be a life time spare supply for a receiver.

But please put me down for 26 of the critters.

Roger Ruszkowski
104 Arintha Drive
Westminster SC 29693

Please post an address where I can send you a check when every thing gets firm.


I know about the #4 cap screw is .111-6, not .096-6.  bolts.
Some times the wrong part would get ordered.
Back in 73 - 75 we were using the .111 not the .096 as we could not get the .096
You picked where you stuck one in and swapped a .096 out to the needed places.
Never put a .111 in the IF and bandwidth switch extensions or the MC KC knob clamps.

I can believe many Fellows have a couple .111 's in their receivers and just think they are
living with a striped out spline.

Roger AI4NI


-----Original Message-----
From: Chris Farley <kc9ieq at yahoo.com>
To: r-390 <r-390 at mailman.qth.net>
Sent: Thu, Feb 27, 2014 2:52 pm
Subject: [R-390] RF geartrain screws


Hi all, 


Well I finally nailed down what is seemingly the one and only *realistically 
priced*  source some of the .096 spline/bristo/bristol screws used on the r-390a 
shaft collar/clamp screws.  *(Still not what I'd call cheap, but then again I 
had one supplier quote me $35 EACH!)  

These are the 4-40 x 9/16" long ones,  4-40 x 1/2" are also used on some of the 
smaller clamps.  9/16" being 1/16" longer than necessary for the smaller clamps, 
they can be left as-is or cut down 1/16" if preferred.  It was discovered that 
these screws are basically unobtanium, as the "standard" spline drive size for a 
#4 cap screw is .111-6, not .096-6.  These screws were a specially made item for 
these (and probably other) radio equipment.  The square nuts and washers are 
much easier to source.  


This screw purchase will likely be a one time buy due to the price and minimum 
order requirements.  Thus this is an email blast to see how many of you might 
also like some, so I can order the appropriate quantity.  


These are the same national stocking number that crosses to the original Collins 
part:  4-40 x 9/16" cap screw with 0.96" 6 flute spline drive, Spec'd to be zinc 
or cad plated steel, MIL-F-14072, yada yada yada. (Surprised these weren't 
originally stainless steel, but indeed they are not upon a closer look).  


For fellow list members interested, my final cost will be about $2.00/ea.  With 
a quick count 13 screws appear to be used per unit, including the two main 
tuning knob clamps.  Cost for a set of 13 with CONUS shipping in a padded 
envelope would be $28.  I may also put "kits" together with the washers and 
square nuts required, but haven't gone there yet.  If some of you wanted much 
larger quantities, say 100+, I can offer a slightly better price per unit.  

If you would like to be a part of this purchase, please let me know ASAP and I 
will place the order.  Note this is for the R-390A geartrain, I have not done 
research for the R-390 to see if they use the same hardware.  


Regards, 

Chris kc9ieq
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