[Hallicrafters] Cleaning switches with aerosol

[Mark Shaum]

---- Original Message ----- 
From: "Mike Everette" <radiocompass at yahoo.com>


> I tend to agree, BE CAREFUL, and LESS IS MORE.

I also agree with Mike.  Sprays are nice for pots and rheostats,
linkages, and variable capacitor bearings in some cases.  On rotary
switches, presuming the shaft and rotors turn freely, the best approach
is a dot of lubricant/deoxidant right at the rotor blades where they
meet the stator contacts.  The Caig "pen" dispenser products, while only
7 ml of solution, will last through many, many switch contact little
drop cycles.

If there is an insulating medium involved, we just have to be aware that
SOME cleaners and lubricants will react with SOME materials.  Actual
instances of phenolic swelling have been reported over the years, but
unfortunately the cut-and-paste document I saved that category of
information on is not easily located this evening.  I know folks have
had difficulties with lab quality gear with very high impedance
circuitry such as the HP 410 and 412 series VTVM's when any type of
cleaning spray was utilized near the switches due to induced leakage
paths.  I have a 410C that didn't settle down until after the range
switch received many, many alternating sprays of alcohol (via an ear
syringe) and compressed air.

You can certainly go overboard with some spray lubricants.  I have an
S-38D where the entire bandswitch, including all connecting leads within
a quarter inch, is completely covered with some substance that has the
appearance of dark green axle grease, for lack of a positive ID. The
rotor tab contacts are quite clean at the small area they use as they
actually wipe between the stator contacts.  And the switch and set
overall works just fine.  Since it works fine, I have not taken the step
of attempting to remove the dark green gunk.  I'll try to post again in
10 years and report if there are any long term effects!

73! - Mark K9TR