[Hallicrafters] RE: Contact Cleaner & Radio Chemistry 101

[Barry Hauser]

Just happened to catch up on the posts and came across this thread on
contact cleaner -- and there was also the one on chassis cleaning.  Some
of this I know first-hand, some is heard-tell and is identified as such:

1.  The present-day closest equivalent of Cramolin is DeOxit.  I thought
I read somewhere that Caig was going to market Cramolin once again for
old time's sake.  (Probably crossed wires or a rumour.)  DeOxit is
available in at least 2 formulations -- D5 which is 5% but has 20%
"cleaning power" (see Caig site), and D-100, which is 100% contact
enhancer/lubricant/oxidation preventative.  You want the D5 to clean the
contacts.  You could use tiny amounts of D100 after they are clean.  I
think they used to have a pump spray that was 20% -- i.e., D-20, but I
don't see that any more.

2.  DeOxit should not be used for pots.  Caig makes Cailube for that. 
DeOxit may destroy the binders used in the resistor material of certain
pots.  Some have used it and survived.  Better to use Cailube or
something else made for pots.

3.  I have heard and have had some direct experience with DeOxit causing
swelling of phenolic wafers and rotors.  It is best to spray the stuff on
mini-swabs or even frayed toothpicks to individually clean contacts. 
First study the switch construction.  If the clearance between the rotor
and wafer is tight, then don't saturate.  There is supposed to be a cure,
and I've heard that the swelling does go down after a while in many
cases.  I had a bandswitch jam up on me once.

The flat of the phenolic is generally resistant, however the stuff can
soak into the edges.  I have not heard of nor had any experience with
DeOxit making insulators conductive.  Sometimes, I resort to spraying
with the nozzle -- the stationary contacts in the SP-600's, the
bandswitch tower on the tube Transoceanics.  For the latter, it's
necessary to remove all of the black goo on the switch contacts.  If you
leave any, it migrates back and continues to cause intermittents. 
Generally takes several applications to clean it and I find I do have to
soak a bit.  I do make a habit of cleaning off any excess.

4.  I have also used D5 to remove light oxidation from plated chassis,
but WD-40 seems to work well in many cases.  WD-40 is also good for
cleaning knobs and most plastics.  (It is not a good long-term lubricant
or for contact cleaning).  Avoid using 409, Simple Green, etc. on
bakelite as it will erode and dull the surface.  (been there, done that) 
This can be fixed with some plastic polish or Brasso, some elbow grease
and patience.  Another often effective cleaner which is kind to most
surfaces is waterless hand cleaner, but be careful, there are two kinds
-- with and without pumice.  When cleaning chassis, try to vacuum out or
brush out as much of the debris as possible to avoid making mud puddles
which run into everything and make matters worse.  Some of the dust may
be abrasive.  Get one of those mini attachment sets that hook up to a
regular vacuum cleaner.  An assortment of nylon or natural bristle auto
detailing brushes and old (or new?) toothbrushes can be very useful.  If
using brushes, hold the nozzle of the vacuum near the brush as you work
it so as not to succumb to the "mummy's curse".

5.  I have read that there is a potential problem with certain cleaners,
like 409, Simple Green, Fantastic, etc. if these are allowed to saturate
phenolic, ceramic or other porous insulators, switch wafers, tube
sockets, etc.  These are supposed to be "ionizing" cleaners and can leave
behind conductive salts which are nearly impossible to clean out.  The
post I read a few years ago told of arcing that resulted from this. 
Someone else confirmed a similar experience. On the other hand, there are
those who liberally apply the stuff and wash the chassis out with a
garden hose.  Dave Medley says he routinely does this with R-390 modules,
but then flushes with distilled water and either oven or sun bakes dry
and others report success with similar procedures.  I have not
experienced or done any of this.  I mention it here because an earlier
post mentioned something about contact cleaners causing conductivity
where it shouldn't be and I suspect the origin may have actually come
from the 409 reports. Before resorting to Simple Green or 409, try
something milder.  A funny thing -- plain ol' bar soap -- fat/stearate
based -- is often just the thing to clean certain forms of goo,
expecially 20 years of fingertip fallout in knob grooves.  Experiment
first with the more benign cleaners, then you can bring out the big guns
if you have to.  These cleaners are available in full strength in the
form of such products as "BH38" which can be ordered from
industrial/janitorial distributors.  

Barry



On Mon, 2 Feb 2004 02:14:10 -0500 Kevin J Ward <kevin_ward at juno.com>
writes:
> 
> I worked in avionics for 15 years or more.  Those radios had lots 
> of switches in them, often ganged with many wafers.  We used Cramolin 
> Spray exclusively; it contains a lubricant, not surprisingly called 
> Cramolin Oil.  Some of these radios were tube types from the sixties. 
Never 
> had a problem with switches swelling or developing leakage paths or
poor
> conductivity.   
> We used Lubriplate or Lithium grease in the detent mechanism.  BTW,
> Vaseline will absorb moisture from the air.  Don't use it as a 
> grease. It's not grease.  
> 
> Kevin  N2IE
> 
> 
> ________________________________________________________________
> The best thing to hit the Internet in years - Juno SpeedBand!
> Surf the Web up to FIVE TIMES FASTER!
> Only $14.95/ month - visit www.juno.com to sign up today!
> _______________________________________________
> List Administrator: Duane Fischer, W8DBF **for assistance**
> dfischer at usol.com
> ----
> Hallicrafters Collectors International: http://www.w9wze.org
> ----
> http://mailman.qth.net/mailman/listinfo/hallicrafters
> 
>