Geo, you make an important point about the purpose of the adhesive blob
that bridges the male connector nut to the threaded portion of the
female connector. I have seen it used that way in all the space hardware
that I've worked on (as well as on fastener heads). I've heard it
claimed that this strictly for inspection purposes (i.e. did the torqued
connector nut move after the unit was subjected to a launch level
vibration test?) and that it provides no significant holding power. I am
not sure I believe that, but non-withstanding it's contribution to
connector nut locking, it certainly does serve as an inspection aid.
When doing tests at work where RF phase stability is paramount, loose
connectors can show up as noise in the test data, so I make a big fuss
about making sure all the RF connectors are properly tightened. The
other thing I fuss over is making sure cables are properly strained
relieved. SMA connectors are small, so if the cable is heavy and/or
stiff it can easily impart enough torque on the SMA connector to loosen
it when things are being moved around or just from gravity. When using
SMA connectors in a ham shack, paying attention to those two things
without having to resort to adhesive staking should suffice in most if
not all cases.
73, Mike W4EF...............
On 12/4/2022 3:44 PM, GEO Badger via TowerTalk wrote:
Do not put any adhesive on the threads. Do get a torque wrench, they won't go out of spec in
your lifetime, or a 5/15" wrench to dedicate to your SMA use. Or a SMA finger
wrench, https://www.rfcafe.com/miscellany/homepage-archive/2014/SMA-Finger-Wrench-Bracke-Manufacturing.htm, that
slips over the nut and you tighten/loosen the connector. They are available in plastic or
brass. It's difficult to over torque a SMA connector, if you're not ham handed. These
connectors are in use in major hi-reliability applications and they do not come loose with
proper application. BTW, there are SMA push-on connectors for the test environment. Also M and
N push-ons.
As pointed out, the shield connection is the interior face of the connector,
not through the nut. Once the assemblies are interconnected, they should not be
moved about unless connected by a very flexible coax.
After the final assembly on can put a dab of Sentry-Seal on the connector where
the threads are visible. This doesn't prevent loosening but will notify the
operator if the connection has failed or been tampered with.
Geo, who may or may not have used a bunch of SMA connectors and their
derivatives in a past professional life, and sold connectors for M/A-COM
Omni-Spectra, who I believe originally developed the SMA.
---
Ciao baby, catch you on the flip side
73 de W3AB/GEOAFA9GB
WA2LSI, KE6RJW, W6B, W7B, AAR9AG
http://www.w3ab.org
Jazz is a pencil sharpener. Jazz is a frying pan… Jazz is a beautiful woman
whose older brother is a policeman
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