The PHILCO Phorum

I recently picked up what I thought to be a Philco 60L radio. I'm sure the cabinet is correct but now after looking at the chassis and comparing it to the 60 schematics I just received, it don't look right?
Also it has been converted to a PM speaker system some years ago. As a new-bee, I think I got took on this one. Help please me identify this chassis so I can order the correct schematic and start the restoration.
Ray








http://www.nostalgiaair.org/Resources/793/M0013793.htm

Looks like a 60 to me but the photos are small so it's hard to say for sure.

Here's a restoration thread on my 60L with lots of photos you can compare to your set: http://www.videokarma.org/showthread.php?t=249144

That's definitely a 60 chassis. Looks like it has been rebuilt a couple times under the chassis, so that might be causing confusion. I have a 60L just like yours in fact and it had to had a PM speaker adapted to it since the original had the cone torn out by someone's bratty kid years ago.

Thanks for the quick reply's Yes, it looks like a lot of work has been done under the chassis, the capacitor block is missing and a
fiber board has been added much like my model 66. Quality of work is terrible on the repairs. Guess I'll forge ahead with the restoration,

Ray

If the original speaker field has been replaced with resistor (and no choke) you'll want to use filter capacitance higher than original.

Bill,thanks for the input on the filter caps. The original e-caps are 8uf, what would you suggest as a substation?

Ray

To get a capacitor that isn't physically too skimpy, you nowadays need to go to about 40uF/450Vdc. This will slightly increase the peak current in the type 80 tube, but the power-transformer impedance will keep within the ratings of that tube. The cadmium on your set looks good. That is what usually keeps me from buying.

I would not go over 15mf on the first filter cap. 10mf is the spec. for that rectifier. You can go larger on the second one provided the correct choke or resistor is in line.

The dial scale is a dead-give away.

It's a model 66, a MUCH better set in my opinion, as it has a wider shortwave band.

Not a tough set to wok on, sometimes the band switch freezes up.

TA, I have a model 66 cathedral radio and when I looked at this one it sure looked like the 66 to me. Been to cold out in the garage to spend any time taking a closer look. The band switch is really frozen on this radio. What or how do you suggest freeing it up? I presently have used WD40 on it hopping the shaft will free up.

Ray

Ah, I guess the 60L and the 66 used the same cabinet then.

The model 66 is a year newer, it was the replacement for the 60 brought out in 1935. I have a 60L from 1933 but I think they carried that lowboy cabinet over into 1934 since the 1934 models have hex knobs and a Bakelite escutcheon. That cabinet was also used with the model 89 chassis and a few others, according to Ron's book and gallery. That cabinet may have been offered with a 66 chassis or it may be a Frankenradio, though a mild one since it's a bolt in.
I would use a filter choke rather then a Pi filter (resistor) either a traditional inductor or a solid state substitute. While you can get away with using a Pi filter in a five tube set a choke filters better with less voltage drop, it can always be bolted to the speaker basket along with the output transformer.
Regards
Arran

Arran, thanks for the information. The 66 chassis bolted right in the 60L cabinet with out any modifications that I can see. I will take your suggestion on the filter choke. I have no idea as to what to order. The schematic shows a resistance of 1140Ohms. I would guess that I need a replacement with approximately the same resistance? Suggestions appreciated.

Ray

The dc resistance in a choke is deliberately minimized, so a close equivalent to the speaker field would be a choke and resistor in series. 8 or 10 Henrys, 75 or 100 mA, and a resistor chosen so the total dc resistance is 1140 Ohms should work. The 1140 figure does sound about right for the old field. Without the resistor, voltages would be higher but probably tolerable. When a maximum capacitor value to be used with a rectifier is specified, the source impedance due to the transformer is usually taken to be zero, and the derived dc voltage taken to be the maximum for which the tube is rated. Neither of those conditions is typical in a radio receiver, and I just use the biggest cap handy.

The size of a filter choke is really not that fussy, but a 10 Henry filter choke would be more then sufficient, in fact it removes AC ripple several times better then a 500 Ohm resistor. The field coil performed a double duty as both a filter choke and an electromagnet, so they used more turns of wire then they would have for a stand alone choke to do the same job. If you want to go cheap you can also built a solid state substitute, a back issue of the AWA Old Timers Bulletin had an article on this, although the iron core choke is probably the simplest solution, at least until you find another speaker.
Regards
Arran