[Nathan Slingerland]

For the rubber tire question - see this article from the tech section:

http://philcoradio.com/phorum/showthread.php?tid=14970

[morzh]

Yes, used the same data for the tires for my 16.

keep in mind: if the existing tire has hardened, it might be a real pain to remove it. I spend over an hour trying to remove the large one. Soaking in various paint thinners etc did not help. No need to make the brass wheel squeeky shiny but try to minimize the residue so no residue remains above the knurling.

[Nathan Slingerland]

I've found it helpful to heat up the old rubber with a heat gun. That softens it temporarily - enough so that I can use a pointed tool to remove it. Any remaining bits I remove using a wire brush (brass).

[morzh]

Yes, also used brass wire brush.

[Chris h]

Thank you Nathan and Morzh for the links. I knew that I saw it somewhere! I had forgotten about the oil filter gaskets. I suppose I will have to pick up a filter. Although the large cross section O-ring seems to be working. The knurl on the tuning shaft is riding on a tangent of the round O-ring surface, not on the largest part of the ring. I don't know how long that will last.

I must apologize for some of the last post regarding the mounting of the tuning dial. In reality, the mask goes behind the dial, not in front of it. (I don't know what I was thinking!) So the felt pads will not ride on the printed face of the dial. The interference with the rivets used to attach the dial are with the tuning bracket, not the shaft end.  The rivets (or screw heads, if used) must be peened to within about 1/16"-3/32" above the back side of the tuning wheel surface to get enough clearance to clear the tuning bracket.

The lamps for the tuning meter and dial originally had a fish paper mask on the lamp assemblies to prevent the light from leaking around the back side of the lamps. One was completely gone and the other just crumbled. I am going to try to fashion a similar mask from some thin fish paper and bond it to the back side of the lamp assembly.

[Sean]

Chris,

For the large rubber tire on the dial drive, I used a couple of square cross-section o-rings I had bought from McMaster-Carr a while back. I did have to make a shim by wrapping strips of cloth around the hub to get the OD of the o-rings just right. If you want to try it I can drop a couple of the o-rings in the mail to you. Let me know if your address is good on QRZ.

[Chris h]

Hi Sean,

That would be great! Thank you. I am good in QRZ.

The trick is getting the right amount of stretch on the ring, or tire. The  O-ring I have now is just right, it just has the round cross section. I may run by the auto parts store tonight and pick up a filter to see how those gaskets fit.  I'll report back once tested for fit. The one that was on it looked like it had some adhesive applied to it in several places, and came off easy. It is still intact, just hard and slips.

[Nathan Slingerland]

The best fitting oil filter gasket according to that tech article (and in my experience) is 'Premium Guard PG195'. I've tried others that are more available from my local auto parts store but the PG195 is a better fit. I usually order them from eBay.

http://www.ebay.com/itm/Engine-Oil-Filte...1675857209

[Chris h]

Thanks Nathan. I have one on its way.

I installed the new tuning dial, shadow meter and the rest of the tuning mechanism, last night. Pretty much as expected; the shadow meter leaves a little to be desired. It will do, until I can find another one. I still need to play with the lamp alignment behind the tuning dial. My lamp leads are too short, and it is pulling the lamp in the BC position. A minor detail, I think.

Now to the RF/IF alignment, and need to do some speaker repairs. It rattles a little. Now I see some tears in the rolled suspension that I had not spotted before. Even with the occasional rattle it sounds pretty good.

[Chris h]

OK, I think I have figured out how to attach an image...finally!!!

This is my experiment with using an O-ring as the driven tire on the dial drive.

[Image: https://s19.postimg.org/jsmuvqk2r/20170804_202529.jpg]

Using this method, I have not used any adhesives to attach the O-ring to the drive wheel, just the O-ring stretch to keep it in place.  As you can see, the knurled drive gear rides near the OD of the rounded O-ring surface. I am hoping that this will keep the O-ring pushed up against the dial and prevent it from coming off.  If not, will have to revert to plan "B" or "C"or...

[Chris h]

When going thru the tubes, I found that someone replaced the #76 local oscillator with a #37. I should have caught this on the first pass, but didn't.  It looks like the 76 is better suited for the LO, but I am just wondering if there may have been a reason for making the swap, other than someone didn't have a 76 available at the time. According to my tube manual they are both medium mu triodes. The 76 has a little higher amplification factor. I don't have a 76 lying around to try it in circuit, but have one on order.  The radio plays well on the BC band, but haven't tried on the short wave bands yet. (No decent SW antenna in the shop). Will the 76 provide a little stronger oscillator on higher frequencies?

[Radioroslyn]

>Will the 76 provide a little stronger oscillator on higher frequencies?

I would think. It's an age old question 37 vs 76, 27 vs 56, and 6C5 vs 6J5.

[Chris h]

Oooooh...new and improved?!?! I thought they were roughly the same vintage.  Especially since the chassis uses both. Makes me wonder if the 76 wasn't a last minute upgrade or fix for a marginal oscillator? It still uses a 37 for the 2nd detector.
Always learning something new and interesting, no matter how old it is.

[Chris h]

I installed a #76 in place of the #37 for the local oscillator, as it should be, resulting in no decernable difference, that I could hear, anyway. With that I proceeded to alignment. IF alignment went off very well, with only slight adjustments.  The RF alignment is a little different story, though. I am going thru the Philco published procedure in the order they have it. When I do the trimmer adjustment at the 5mHz (roughly) dial setting, the trimmer is a little different from anything I have seen before, and is very touchy. I have adjusted it as close as I can. (I am using a tape wrapped nut driver, as I don't have a non metallic driver. Making very slight adjustments and pulling the driver away... Not the best but all I have.) The rest went ok, adjusting to the dial frequencies, with the generator set to the dial settings, and keeping output as low as possible. But something just isn't right. I can't put my finger on it. The sensitivity of the receiver just doesn't seem to be as sensitive as I have seen on other radios. I have gone thru the RF several times, but it is no better. On a tuned loop antenna, signals are real good. On a short piece of wire, tuning to local BC stations, the signal strength on the weaker stations just isn't as good as I have had with other radios of similar vintage. Maybe it is good, and I am expecting too much. Sorry for the sketchy description, but can't seem to describe it any better. Perhaps it is the lack of a tuned RF stage?

[462ron]

Chris, I have 2 long wire antenna sets that I have used the tuned loop antenna on, a 620 and a 37-116. On both sets, improved sensitivity and less noise pickup was experienced. Much better performance than using a long wire antenna.

Ron