Hello Every Radio Restorer,
I'm still working on this Wilcox-Gay console radio. Can't find the schematic for it anywhere
and have a 1 or 2 watt resistor fried with two legs left. Trying to use other Wilcox-Gay
schematics to find it. Can anyone tell me what a "MICA DIODE FILTER CONDENSER"
is and what it looks like? There are three, I think capacitors in the radio, that are flat 3/32" thick
with a hole on one end for a ground screw and a 1/2" high solder lug on top. One has one
solder lug and the other two have two solder lugs on top. They look like steel wraped
around plastic (Mica?) with thin small pieces of (Steel - Glass - Plastic - Mica ?) in the center. One
is short 1/2" long and the other two are about 1 1/4" long. These maybe the "Mica Diode Filter
Capacitors?" Any help would be appreciated. Thanks so much,

Sincerely, Chris

What you describe is a low value mica cap and as filters, they are usually used in pairs in the AM detector circuit (75, 6Q7, 27's...) to remove the IF from the detected audio signal. It would be extremely rare for one of these to go bad; don't mess with it. As for value and with an IF above 450KC, each of the capacitor of the pair should be around 100pF and have 50K resistor between them; it all depends on the actual IF frequency. It's not common to put a name to this part of the circuit but after all it is a low pass filter.

Having no idea what model or vintage radio you have, I can't go any further. Have you checked NostalgiaAir for a schematic?

Pete

Funny wording, think of it as "Mica Filter Condenser for Diode", where "diode" means "detector". Low-value mica cap, probably in the low 100's of pF. It sure enough is a filter cap, but the ripple is at RF not 60Hz.

Dave Wise

Agree, probably 110-20 mmf would work here.

Thanks to everyone who replied to my post. I've been an engineering/technician for over 40 years and it proves your never to old to learn something new - that's old. Very funny wording for a mica capacitor but that was some 77 years ago. Their all in good shape and I never touch any micas in any radio. They have temperature coefficients all over the place and in the oscillator a new one will cause it to drift terribly. One is 50pf and the other two 100pf, they are used in the 1st and 2nd IF amps both #78 valves. I have looked everywhere and asked everyone on line who sells schematics trying to find a model number for the Wilcox-Gay Console with no luck. Been going thru Rider's and finding similar radio's with a 6E5 (Magic Eye) to get an idea what value the burnt resistor is. I've had the radio for 46 years and it finally died three years ago, dumb me I should of replaced the components a long time ago. Just finished two Crosley's except for sanding and repainting the plastic cases. Then it's on to a Philco cathederal and a Motorola tombstone both from the 1930's.

I placed photos of the Wilcox-Gay last year in the forum so i'll place them again soon in hopes someone might know. These radios were made 15 miles southeast of where I live and have asked the Charlotte, MI - Chamber of Commerce & City Hall/Courthouse and they have no records of the business. I guess it was never there? Well, Thanks Again to Everyone and I hope to help someone out like you helped me, 73's Chris Hethorn, KM8X

Can you trace where this resistor is placed in the circuit, maybe draw a partial diagram? An example would be it goes from pin 6 of tube #xxxx to the B+ line. This might be enough info to make an educated guess as to the value of the burned resistor. Probably a shorted cap took it out.