[R-390] Re-hardware

[jcoward5452 at aol.com]

Hi
  I would replace hardware with as close to original as possible for the 
reasons mentiond.
  As to split lock washers:I worked for Avantek , a supplier of mil spec 
RF gadgets and wizbangs for 10+ years and all our hardware that used 
screws to hold it all together,was pan head phillips,split lock washer 
and flat washer, all stainless and this hardware combo was specifically 
called for in all the mil-spec requirement docs.The "ground" is 
provided by the contacting surfaces of what is being screwed.The 
lockwasher is there to provide some back tension against vibration.The 
flat washer was there to protect disimilar surfaces from getting gouged 
and becoming a source for corosion failure.Try submitting a test sample 
for "salt fog" testing and you'll understand a whole lot by what you 
get back!I thought it was a pain in the a** to load  0-80 screws with 2 
different washers and then get it all started without loosing it all or 
crossthreading the screw in the attempt! But thats why microscopes and 
tweezers are useful for us ageing buzzards. And, your hard work paid 
off when you passed the sine sweep and random frequency vibration tests 
and the most feared "drop test".Centrifuge was another one of those 
feared tests.I guy I worked with designed a couple of dielectric 
resonanator oscillators for the 2 and 3 gigahertz applications and sent 
them off for centrifuge qual.Well, the techs at the test lab misread 
1000g's as 10000g's.well the ceramic thinfilm circuits and the ceramic 
resonator turned back into their elemental nature.After cutting open 
the cases all that came out was dust and gold flakes.The screws and 
circuit carriers were still in place though.
 Jay

-----Original Message-----
From: bmw2002tii at nerdshack.com
To: R-390 at mailman.qth.net
Sent: Sat, 9 Sep 2006 11:43 AM
Subject: Re: [R-390] Re-hardware

Perry wrote:

> the SP 600 uses pan head flat slotted cadmium plated screws and star
> lockwashers. What are peoples thoughts about replacing it with
> stainless steel cross point screws and using SS split lockwashers
> instead of the star type?

It depends on what you want to end up with. If it is purely for your
own enjoyment and you don't care about resale value, replace away. But
most folks wouldn't pay full value for a radio with non-original
replacements, even if they were "better" than the originals. Split
lockwashers are not as secure as the star type, and also do not create
as good a ground connection wherever that may be important (although in
home use, neither is likely to cause any problems as a practical
matter).

Best regards,

Don

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