Philco 89 (123) (Update-Coil rewind) - Printable Version

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+--- Thread: Philco 89 (123) (Update-Coil rewind) (/showthread.php?tid=1934)

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Re: Philco 89 (123) UPDATE/Coil rewind? - Ron Ramirez - 08-15-2009

gary rabbitt Wrote:Here are the questions I am dealing with right now.

***Is this the winding that needs to be rewound after the "baking in the oven" procedure? As seen in the photo it's the smallest winding.

***How many turns should it have? I believe I have the same diameter wire on hand.Looks like about 29 to 32 turns.

*** Is the winding just one layer?

I assume there are no taps on this winding. The diagram shows just a small coil on the Cathode of the 36 tube.
NOTE: I had measured this winding when I first started and it measured 150 Ohms. The spec says 5.25 Ohms.
Probably part of my original problem.

Okay, Gary...let me answer your questions in order...

1. Yes, that is the winding that always goes bad. Bake the coil in your oven at 180-200 degrees for about 30 minutes. Remove from oven and wipe off the excess wax.

2. The cathode winding, which is the winding your arrow points to in your picture, should be 28 turns of 38 gauge enameled magnet wire. Wind the turns clockwise as you are looking at the bottom of the form (where the lugs are).

I should add at this point, that you should throw away that old nitrocellulose insulator under that winding, and use Mylar tape instead as insulation between the inner and outer windings. You can hold the beginning and end of the winding in place with dots of hot glue, carefully applied.

3. Yes, just one layer. No taps.

When you are done, spray the coil with some clear Deft or other clear lacquer. This will protect the coil much better than the wax ever did.

Good luck.

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Re: Philco 89 (123) (Wirewound resistor Wattage) - gary rabbitt - 08-15-2009

Thanks Ron.
I will try and rewind it today, it shouldn't be that bad to do.

The other windings look ok, but when I took the inner coil form out, (shouldn't have) I broke one of the wires on that form. I did a micro mini splice to repair that so it should be fine.

I'll let you know how it turns out, and thanks again.
Best regards,
Gary

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Re: Philco 89 (123) (Update-Coil rewind) - gary rabbitt - 08-16-2009

Well, the coil wind went OK, reinstalled it and I have the same problems.

Mainly a squeal when tuned to the higher freqs. But it is not constant.

The set would pick up great say 1200, then tuning thru 1280, then higher it starts to squeal. Tuning back, the squeal does not stop. YOu have to fanagle with the tube caps, or touch the grid of the 2nd Det to 'reset' it.

I can take off the grid cap of the 36, and will stop. Volume down and cap reconnected, the set will receive ok on the high half of the band.
If I turn up the volume and tune higher than about 1200kc the set will squeal again.

I have canged the Osc cathode resistor to 8000 Ohms, but have tried other values. The only thing that changes it the squeal pitch. A 1300 Ohm squeals a lot lower.

Here is something I don't understand, when the grid cap is off the 36 tube, I can tune the lower end of the band. Otherwise the low end is not receivable. After about 750 kc the noise drops off, and I can't pick up a signal.

I am going to realign the IF tonight, but I think it is pretty much dead on at 260kc.

There is something that I am overlooking, but as far as I know, I"ve been over the set a few times, and all resistors within spec.

I dislike giving up an a set, but this one is giving me grief. Same situation os Chuck's Philco from He__*
http://www.philcorepairbench.com/tips/svctip42.htm
I only have one other #36 tube to swap, but it shows the same issues.

Perhaps making a little video would be in order.

I'd like to get this off to the owner, but I am afraid that I will not be able to get it working right.

Take care,
Gary.

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