[TowerTalk] F12 C19XR Rivets

[Jim Thomson]

Date: Tue, 8 Mar 2016 15:22:32 -0500
From: "Bert Almemo" <balmemo at sympatico.ca>
To: "'Roger \(K8RI\) on TT'" <K8RI-on-TowerTalk at tm.net>,
<towertalk at contesting.com>
Subject: Re: [TowerTalk] F12 C19XR Rivets

I learned long time ago that using pop rivets, blind or not, don't make for
a good electrical connection. For all antennas, using aluminum tubing, I've
used self tapping screws for the last 30 yrs and it's served me well. It's
also much easier to take antennas apart and put them together again using
screws. As always, OMHO!

73 Bert, VE3NR

##  The electrical connection is between the mating aluminum tube surfaces, not the  rivets/
self tapping screws.   A  1 inch OD al tube, with say a 3 inch overlap, will have 9 square
inches of surface contact.   Unless the self tapping screw is SS, it will rust.  If it is SS, then
you have the dissimilar metal issue.   Mosely etc, uses  SS  self tapping screws, and they work
just fine.   Heck, I used a single slot + SS hose clamps  for several years on my hb yagis...and
they worked just fine, with 100% of the RF flowing through the mating surfaces.   Hy-gain, wilson
etc, used those compression clamp assys....which I just hate with a passion.   Local fellow here had a 
hy-gain 204BA  up 100 ft near a cliff edge, and after a few years, some of the tips and inner sections 
were just about ready to pop right out.  They had migrated outboard quite a bit.   Same fellow also
had the old KLM 4 el 40m yagi......and it self destructed.   It was new at the time.  He ended up
buying a bag of SS  self tapping machine screws, and drove em in everywhere.   Problem solved
with the ele migration problem.  Next problem was the KLM 40 eles came right off the boom.
The ‘fix’  for that was to use multiple SS hose clamps to hold the lexan brackets to the boom.
Then drive SS self tapping screws through the slots on the SS hose clamps. 

##  I have never seen  SS self tapping machine screws ever loosen up, they seem to hold stuff
together quite well, just don’t  crank em in too tight, into al tubing,  such that they strip out. 

Jim   VE7RF