[Hammarlund] Thanks for help/Dial slipage on SP600

[Barry Hauser]

On Fri, 10 Jan 2003 08:05:41 -0600 "Charles and Sandi Hugg"
<chashugg@earthlink.net> writes:
> Thanks to all who responded to my plea for help on my dial slippage 
> problem on my SP600. I will try the suggestions this weekend. It may
require 
> some additional cleaning or lubing of the geared tuning mechanism. It 
> seems kind of tight, like it is taking a whole lot of effort to turn
it. Any 
> ideas on how to lube this?
> Thanks again for all of the help. This group has been a big help.
> Charlie Hugg, K5MBX

Charlie (& gang):

Recommend you don't try ALL the suggestions, particularly involving
solvent near the dial disk.  As someone pointed out, some solvents will
take the paint off the dial.

The correct method for lubing the SP-600 tuning mechanism has been the
subject of some debate.  There are those who might say the mechanism is
not to be lubed at all.  That's basically true, but not exactly.

One of the service manuals, AN16-45-222  says  "The radio receiver
requires no lubrication during the life of the receiver."

Yeah, but get this.  It goes on to say:  "The life of the receiver within
the scope of the present maintenance activities is ended whenever the
receiver is subject to depot overhaul.  The receiver overhaul
requirements may necessitate re-lubrication at the depot."  At this
point, it may be prudent to retain a boatanchor attorney, because it
sounds like a lawyer wrote part of the manual. ;-)  It also says, in
essence, that any replacement subassemblies from the factory that have
moving parts are supplied pre-lubricated.

As with many documents, both modern and ancient, there is a "catch". 
Here it's this "life of the receiver" business. Apparently the SP-600
dies and then is reborn again after a visitation to the depot.  Then, and
only then is it to be re-lubed -- only if it needs it.  There is no
mention of specific time frames, lifetimes per radio or per customer, nor
is there a clause about boatanchor enthusiasts in the 21st century.

OK, it doesn't end there.  We then go to AN16-45-223, the overhaul
instruction book for guidance.  (The depot 'r us!).  Page 7 deals with
cleaning and lubrication.  It specifies kerosene and carbon tet for
cleaning the gears and various metal parts.  It indicates two kinds of
grease to be used -- one for the tuning capacitor bearings and another
for the other shafts/bearings, which it lists and refers to a diagram on
page 5.  

Apparently, all the lubrication is with grease on bearings and shafts. 
No mention of oil or any lube on gear teeth.  However the gear teeth
should be clean.  The manual suggests using a pipe cleaner, but a small
flux brush (no flux) or stiff-bristled artist brush works well.  Just
don't splash any solvent around.

As for re-lubing the shafts -- doing it right involves disassembly of the
mechanisms.  The grease should be fairly heavy -- not something that will
run or drip.  If the existing grease has gummed up and you don't want to
tackle a teardown, there is a technique I've used with some success.

First, make sure the gear teeth are cleaned out.  Dried grease and dirt
may be causing binding.  Then, apply some penetrating or light machine
oil to the bearings while working the mechanism.  Let that seep in and
"revitalize" the old grease.  Wipe away any fallout with a swab as you
continue to work the thing.  Then, follow up with a small amount of Mobil
One motor oil or gear oil -- a drop or two and get that to work in and
displace the witch's brew you just made.  If you use penetrating oil
alone, the bearing will loosen up, but then dry like glue a short time
later.  Ideally, the mechanism should be disassembled and cleaned, then 
greased as it is reassembled.  The right grease is too thick to work into
the bearings with everything assembled.

The two manuals -- and others -- are available on Andy Moorer's website
along with others. (Thanks Andy)
http://www.jamminpower.com/main/sp600.jsp

There 'ya go ...
Barry

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