<<<SPAM>: Re: [R-390] Cosmos PTO, spring-loaded linearizing core?

[Tim Shoppa]

Jim M. wrote:

> If I recall correctly, and it has been a while, the core of the
linearizing 
> coil is spring loaded inside in some fashion so that it moves in and
out as 
> the adjustment screw heads push against the slide (I dont have better
names 
> for these parts).

That was my understanding too. What I do NOT understand is why there's
no spring action and no spring and no slide inside this VFO's
linearizing
coil.

>  I dont recall if there was a lot of tension or not but 
> when you push on the little "nub" the coil core should go in slightly,
and 
> then spring back when you release the pressure.   The pressurization
inside 
> the can (if there ever was any) has nothing to do with it.  What is
going on 
> that you think this coild may be the problem?

Again, no spring action. Disassembly of the linearizing coil shows no
spring.
In fact the core sits on a screw that is threaded through the base.

It is VAGUELY possible that the base is actually two pieces, and the
threaded part is supposed to be sliding in and out. But pushing and
tugging
firmly on it shows no sliding. And it looks like it's just one solid
piece.
(And externally looks just like all the pictures).

If someone told me that this cylinder was supposed to slide, I might
start
putting it in a vise hammering on it or something. But short of that
it's not
gonna move.

> The only adjustable coil I know of with screw threads is the end point

> adjustment coil right next to the linearizing coil.

Yeah, I've got the end point adjustment coil and it is threaded.
(Actualy
the threads are not on the coil but on a brass insert in the bulkhead
that the
coil attaches too.)

BUT... my linearizing coil has a threaded base, and a core on the end of
a threaded screw. No sign of any spring or slider at all. Thus my
complete
mystification as to how it ever worked.

My pictures look just like those on the other websites of a Cosmos's
innards,
except that none of them ever got so far as unscrewing the linearlizing
core
to look for how it was supposed to work. Oh, one difference: on mine the
nub behind the ring isn't red, it's black. Don't know what that means.
It
looks original, it's a very snug fit into the bottom of the linearizing
coil's base,
but so snug that it never could've slid in and out.

I'm tempted to tear down my other Cosmos PTO just to see what the heck
is inside it.

>   If it doesn;t look like what's 
> pictured on the URL inside, then maybe it is something different or it
has 
> been modified sometime in its life.

Mine *had* been rebuilt by Raytheon (according to the maintenance
sticker)
sometime in the early 70's. But the coil base looks identical to the
other Cosmos
pictures I've seen around (of course they only show the outside of the
base
and not the threads or the slug on a threaded screw on the inside). The
only
obvious difference is that the nub that is supposed to ride the back of
the ring
is black plastic on mine.

The reduction drive for turning the screw plate in mine was pretty
grungy. Not
as much shellac and grit as the RF deck geartrain, but pretty bad for a
sealed
unit!

Tim.