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Philco 51-930 resistor and capacitor questions - Printable Version

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Philco 51-930 resistor and capacitor questions - radiorich - 04-20-2022

Hello Everyone,
in between other work I have been plugging along on my Philco 51-930 radio chassis I have a Questions one concerning R5 the Filament dropping resistor which looks like a old style dogbone resistor is no good So since reads 2000 ohms and schematic say 100 ohms.
I will need to calculate a high value because of our higher line voltages and far as wattage goes and type resistor should I go with?

Far as C8 that should be a safety capacitor and I am thinking C2 too.  
C12, do you think I need to put a high voltage capacitor or can just use a one yellow capacitor rated at 630 volts since this is just plain old AA6

 Here is a photo of that R5 and the Schematic 

Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - Radioroslyn - 04-20-2022

At 100 ohms that sets the filament string to operate at 115v. If you increase, it to 166 ohms that will set filament string at 125v. Dissipation is 3.75w so I would use a 10w. Closest common value would be 160 or 170 ohms. Either would work fine. Don't know that I'd bother to change C2 or C12 to a different type.

RE: Philco 51-930 resistor and capacitor questions - radiorich - 04-20-2022

Hello Terry,
Thank you for your advice !

I know question was a little long winded thou !

Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - Radioroslyn - 04-20-2022

On 2nd thought I might add a series resistor to C-12. This will brighten up the high frequency audio response. Something like 100K to 200K. Value is based on your sound preference.

RE: Philco 51-930 resistor and capacitor questions - Ron Ramirez - 04-20-2022

Richard,

Here is another idea - it is of course up to you if you wish to pursue...

Replace the 35L6GT tube with a 50L6GT. This will set your filament string at 116.5 volts without the dropping resistor. Now, replace the dropping resistor with a 56 ohm, 3 watt resistor. This resistor will set your filament string at 124.9 volts, close enough. Smaller dropping resistor at less wattage (it will dissipate 1.26 watts of power), your radio will be happy and so will you. Icon_smile

The 50L6GT is a plug-in replacement for the 35L6GT. Only the filament voltage differs.

RE: Philco 51-930 resistor and capacitor questions - radiorich - 04-20-2022

Hello Ron,
I think replacing the 35L6GT with a 50L6GT is the easiest way to solve the issue!
The radio will be really happy with those voltage and extend the tube life .

Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - radiorich - 04-20-2022

Hello Terry,
So, I am guessing the 200k would making it brighter sounding far as the audio tone goes then the 100k ?
You Said in Series, right? So maybe I will add a terminal strip between the audio output trans and C12 so that I can tack in the resistor to see what one sounds the best .

Sincerely Richard
P.S. worst thing about restoring this radio is replacing the bad tuner grommets .

RE: Philco 51-930 resistor and capacitor questions - Radioroslyn - 04-20-2022

Yup,you could use a 1/2 meg pot to find what you like and measure it's resistance. You can use clip leads to connect the pot for testing the proper setting.

I've got those washers to do a my 201 chassis and the two front ones are darn close to being under the band switch. Grrrrr. Have been waiting for a reply from Chris ( Renovated Radios) and Mark Oppat on the availability. Normally I make them up from hardware store parts but this time I want to get something that is easy to fit the first time.

RE: Philco 51-930 resistor and capacitor questions - radiorich - 04-21-2022

Hello Terry,
Yes, I feel for you far as those Washer's go far as the set, I am working on the dial string i don't want to have it come off when I have to move the tuning capacitor.
Far as Renovated radios goes, I have not ordered from them since Ed had it.

I am looking towards hearing this radio afterwards being it has a 3-gang tuning capacitor it should pull in some those late night am stations .

Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - radiorich - 09-24-2022

Hello Radioroslyn ,
Well I did order the tunning gromments for my Philco and I able to get the grommets in place with out completely restring the tuning dial !
Hope yours goes as easy as mine did Terry,
Well guys
As I am pluging along replacing capacitors and resistors in this set I ame across a issue as you know most of these sets they would switch the neutral side of the line and I was wondering if I should go ahead and change it around on the switch since this set is getting a new Polarized cord and fuse because either way the hot will have a fuse.

the thing is I will have to rework some the wiring and add a terminal strip to move the neutral wires to

Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - RodB - 09-24-2022

I almost always move the switch to the hot wire. If you don't then you have 120 volts at each tube filament waiting for you to touch it.

RE: Philco 51-930 resistor and capacitor questions - radiorich - 09-24-2022

Hello Rob,
Yes I hear you just this radio will intail some rewiring and a terminal strip !
Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - radiorich - 11-09-2022

Hello Everyone ,
Well I have been putting this radio off for a while but I finally am down to just putting in that resistor in series with the .02 ufd .
Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - radiorich - 11-11-2022

Hello guys,
I have a question Far as Ac ripple I finished restoring this Philco 51-930 using my fluke 87 I measured about 3 volts Ac across the first Filter cap off of the rectifier tube C7c which is 47ufd I read about 3 volts ac across it and C7b which is a 30ufd reads just like 1.00 volt ac the Dc on both capacitors is just fine and I hear no AC hum .
So is the reading just caused by what meter that I am using or what do you think ?

Sincerely Richard

RE: Philco 51-930 resistor and capacitor questions - David - 11-11-2022

Those readings look to be about right for a half wave rect.