[Guest]

This only happens when the gang totally closes. It does not appear to be due to bent plates but rather the rotor going too far and touching the stator.

I have made a fix by putting a loop of black lacing string, between the middle two plates of each rotor section. This simply goes around the bar that holds the plates together.

In practice it works but I wonder if anyone else has come across this or if there were originally (now missing) some sort of stops that prevented this from happening?

thanks Gary

[AI2V]

Look to see if there are any outside rotor plates that somehow got bent in to create your short. Don't be afraid to bend the outside plates- that's why they have slits cut in them. After that-

On the back of nearly every tuning cap rotor is an adjustment screw with locking nut that adjusts the axis depth. It's rare that this needs adjustment and it is only used when there is a large dial tracking error in the middle of the dial.

You can usually see that the rotor and stator plates are not centered (evenly spaced) and if they aren't, this adjustment needs to be made. It will often eliminate shorts at max.C.

If you have a capacitance meter, disconnect any wires going to the stator and adjust the rotor axis screw for minimum capacitance when in full mesh.

After doing this adjustment all alignments in the procedure after the IF must be done over.

[Guest]

Thanks for your interest and reply but this is not the answer. I had previously had the gang off and cleaned and checked all plates etc. This included removing the rear bearing, cleaning all the old gunge and relubricating it and the front bearing. All nicely set up for no end float on the rotor but the least resistance to turning. This is essential else the dial cord drive will slip.

Actually the problem is interesting. It got me looking at other tunning gangs in 'stores'. Old 20's ones have a pin on the rotor shaft that limits the rotation. Modern ones have the ends of the rotor joined by a punched paxolin panel. When this contacts the fixed non-earthed plates it obviously doesn't short them out. Not so with my 118 which has a metal plate, to secure the ends of the rotor. So there must have been something that limited rotation or prevented shorting. This is the most likely and possibly there was an insulating buffer secured (glued?) somehow. It explains why my loops of lacing string work.

So, bit of a pain, but I will have to look in my other Philco's and look at the gangs on those.

Gary

[AI2V]

Why not push a small piece of wire insulation between the plates up against the plate separator?

That will reduce rotation travel only a fraction of a degree, and supply a soft rotation stop with insulation.

[Guest]

Thats not a bad idea Peter and neater than my lacing string. I could even put a dab of superglue on it to hold it in place.

I am interested in how it was done originally so I will inspect my other Philco's (I dont have another 118)

thanks Gary

[etech]

Gary,

It is interesting that you brought this topic to our attention. I have a Philco 90 chassis here that has the same issue. That is, the tuning condenser has one section that shorts at full capacity. The same as yours, this is not an issue of bent plates shorting. It is what I would consider over travel of the rotor. I have never really pursued it since it occurs below 550 on the dial and no damage occurs to the radio when it occurs. It is interesting that both are Philcos, though. Maybe our resident Philco experts can chime in on this one?

Ed

[gary rabbitt]

HI, Just a thought,

I was rediong a Philco 20 and had the same issue. IIRC, I has to make sure that tha the end of the dial travel, the tuning cap was just above the shorting point.

So perhaps putting your dial on the extreme end of travel, then loosen the tuning cap shaft and raise it up just slightly, like a couple of mm, so it doesn't short.

I didn'lt find the exact location the plates would touch, that may be the best solurion, then isulate that point.

[Guest]

Had a look at a Model 60 and there is a spacer that stops the gang being shorted out at max capacitance.

[Image: http://i236.photobucket.com/albums/ff64/...odel60.jpg]

This shows the spacer from the top but it extends inder the plate as well. Presumably the moving gang plates are stamped with a notch so the spacer fits flat. It can be seen with a torch but I couldn't get a pic of it.

So why not something like this on the Model 18? Are they all like mine? Does it matter? Not really, it stops the oscillator but does no harm. Anyway I have left the loop of lacing string, as the original post and that stops it happening.

Gary