[R-390] EAC Rocketship project--PTO endpoints WAY out.

[Larry H]

Glad you're making progress, Bob.

If the pto is good mechanically (tuning shaft: 1. turns smoothly, 2. no end
play, 3. has good light turning resistance (not too hard), and 4. is
straight,  then it might be worth while to try to save it.  Also check that
there is very little slack in the linearity compensator gear when the main
shaft is turned back and forth.  You can look through the linearity hole
and watch the disc move.  There's lot's of good info about them.  There's '*A
JOURNEY THROUGH THE COSMOS (PTO) by *Jim Miller at:
http://www.r-390.com/cosmos.htm  and mine at:
http://www.r-390a.net/Pearls/PTO_Cosmos_Observations.pdf and Tom Marcotte's
in the PTO section in the Pearls at the end:
http://www.r-390a.net/Pearls/PTO.pdf

18 kh is too much to correct by removing 1 turn off of the ep coil.  One
turn on a cosmos is about 6 kh.  This is less than the others, due to the
extra compensating coil in the circuit.

Keep at it and have fun.

Regards, Larry



On Fri, Aug 24, 2018 at 5:51 PM Bob Weiss <bobweiss1967 at gmail.com> wrote:

> Have been plugging away on the EAC, and have it up and running , at least
> well enough to pick up local AM stations.
>
> The Cosmos branded PTO cannot be endpoint adjusted, as the adjustment screw
> runs out of range. Unit is out by 18KHz over the 10 turns travel.
>
> It appears that a previous owner was already poking around (first sign of
> any work other than tube changes) in the PTO the factory seal tag has been
> violated, and signs of the green mounting screws and the endpoint adjust
> screw having been "diddled"with quite a bit previously.
>
> Anyone have a good PTO available, or thoughts on how to repair this one? I
> have heard about removing a turn from some internal coil?
>
>
> In other project notes, I was surprised to find the meters on this unit to
> be just as "hot" as the old ones I pulled from my Stewart Warner.  Trying
> to track down a suitable set of replacement meters for this one. I had
> heard that the later production were supposedly non-radioactive, but this
> being one of the last units built, I wonder how it got hot ones, which look
> original, no evidence of swapping.
>
> The cores in the IF cans are VERY stiff/sticky, particularly the bottom
> slugs.  Any particular solvent/heat technique to break them free without
> damage?
>
> Found a couple completely unsoldered connections in the AF deck, on the
> filter can sockets. They do seem to have been making good contact, no sign
> of arcing. Assembled on a Monday, and inspected on a Friday, I guess?
>
> After the recent thread about the filament choke burning up in the RF deck,
> I checked the area on mine. Mine was also quite close to grounding out on
> the chassis, but no sign of arcing/burning, so I redressed it slightly and
> it should be fine.
>
> Have lined up a set of IERC shields to replace the cheap silver ones (many
> of which are cracked/split). Guess the civilian market didn't rate those?
> Or were they all field change additions?
>
> The civilian unit apparently didn't ship with the tools attached to the
> rear panel. The spring holders for them were never installed.
>
> 73,
> Bob Weiss N2IXK
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