[Hammarlund] Cleaning Old Radios, second steps

[Tisha Hayes]

What I have found that takes a radio to the next step after the scrubbing
and cursing is to replace all of the screws, washers, nuts and bolts with
stainless hardware. This is a good opportunity to re-cinch all of the
hardware and do spot-cleaning on places you would never see. It is amazing
how organized everything looks when you get rid of the poorly done
cad-plated screws. I even replace the screws holding the coax connectors and
terminal strips to the rear chassis.

Of course I am a heathen and have diverged a bit from the factory standard.
I have an obsession with Type N and TNC chassis connectors so all of the
coaxial hardware has been pulled and "Tisha-graded" to comply with
everything else I use (down with the PL-259!).

I am fortunate enough to work for a company that has a panel fabrication
shop where I can use whatever I need for small hardware. Since the things
our company make end up in corrosive atmospheres, everything is stainless
hardware. Going to a hardware store to pick up 4-40, 6-32 or 8-32 stainless
hardware will set you back some cash.

If you feel comfortable with dropping the front panel and undoing the
geartrain, you can really make this area shine. The front sub-chassis where
the gears mount is cadmium plated and usually looks like hell. I have used a
metal polish with a drill mounted lambs wool buffer pad to take off at least
some of the grime and put down a protective finish of polish. Then you can
hand polish all of the brass gears, lube up some of the totally inaccessible
places like the floating bearing ball between one of the gear shafts and the
sub-chassis plate and the spring loaded tension plates for the gear-train.
It is amazing how many of those floating plates are locked in place or where
the tension spring has no tension.

While in there, get some grommet material and make a grommet for the
wireways between the lower chassis and the front panel. Unsolder switch
leads and put heat shrink on some of the wires that have cracked insulation
from the abrading contact with the circular wireway. On one of my
restorations, nearly every front panel switches were frozen so I replaced
the front panel switches and one bad potentiometer that could not be
restored with DeOxIt. I removed a bit of the spring loading tension on the
band switch as I was getting a Hammarlund version of R-390 wrist while
changing bands.

The biggest pain in the arse was making sure that the magical metal on metal
contact that gives the tuning dial on the SP-600 it's special feel was
absolutely clean of anything that has lubricating properties and the
electro-mechanical-magic connection near the flywheel would work
consistently.

I had not been clear on the questionable uses of WD-40 in my first post. The
only place I see it as having a value was as a water displacer. For a
quickie wipe-down of a chassis it is fairly good at removing crud but it has
few other redeeming qualities.

Oh, if you do the water bath procedure, you really need to be careful in
powering up the rig for the first time. I would suggest checking every cap
for a sudden departure into the realm of being a resistor or fuse. If you do
have BBOD's (and even a few poorly installed ceramic disk) capacitors the
water may creep it's way inside of the component and short it out. I have a
old Biddle megger that I use to do ground system testing and with a pair of
alligator clips I give each cap a litmus test with a hand-cranked megger to
find the definitely bad caps. BTW, this is not a good way to find out the
capacitance, just a tool to rapidly find shorted caps.
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