Late 1920s Eveready Model 1 TRF Set need info

[vortalexfan]

Originally Posted by Kevin Kuehn

Re-stuffing those cans would be ideal if you can get inside them. Take pictures and try to keep the external wiring as close to original as possible.

That's what I was planning on doing, I'm assuming that film caps would be used there as well? I'm asking because if you take a look at the picture of the caps there is a definite "ground" and positive lead to these capacitor cans and I was wondering why if they just used non-polar paper caps why would it matter if there was a ground and a positive lead to these capacitors (in this case the can's housing is the "ground" and the capacitor hookup terminals are the "positive" leads.)

Or is the "ground" more of an "RF Ground" to keep the noise down in the radio, since these capacitors are associated with the Tuner/RF stages of the radio?

[Kevin Kuehn]

Originally Posted by vortalexfan

That's what I was planning on doing, I'm assuming that film caps would be used there as well? I'm asking because if you take a look at the picture of the caps there is a definite "ground" and positive lead to these capacitor cans and I was wondering why if they just used non-polar paper caps why would it matter if there was a ground and a positive lead to these capacitors (in this case the can's housing is the "ground" and the capacitor hookup terminals are the "positive" leads.)

Or is the "ground" more of an "RF Ground" to keep the noise down in the radio, since these capacitors are associated with the Tuner/RF stages of the radio?

Yes Film. Definitely for RF grounding. Relocating them or their wiring can be a big no no.

[vortalexfan]

Originally Posted by Kevin Kuehn

Yes Film. Definitely for RF grounding. Relocating them or their wiring can be a big no no.

Ok I have a question, concerning the bypass caps in this radio.
Two of the bypass caps are marked on the base of the caps and on the schematic .5 (they are two singles marked at that value) and one cap is a double cap marked 1. on the bottom of the cap and on the schematic, what's the purpose of the decimal point (.) after the 1 on the double cap? I'm assuming it's a 1 MFD capacitor which if that's the case why bother with a decimal point after the 1 on the capacitor markings?

Also how would I restuff the 1 MFD bypass caps? I ask because I think a 1 MFD 630 VDC film cap is going to be too big of diameter to fit inside the can, let alone two of them.

Also as far as the .5 MFD caps go, I'm assuming a .47 MFD 630 VDC cap will work fine in its place?

Also I was wondering how I would go about handling the wiring going to the RF bypass caps because while the rubber insulation of the wiring is still intact and isn't falling apart, it is very brittle to the point that just moving the wires just slightly causes the rubber insulation on those wires to crack and chip off the wire which if I'm going to restuff those bypass caps I would have to move those wires and I don't want to have to replace any more wiring than I have to in this radio to get it up and running.

[Kevin Kuehn]

Originally Posted by vortalexfan

Ok I have a question, concerning the bypass caps in this radio.
Two of the bypass caps are marked on the base of the caps and on the schematic .5 (they are two singles marked at that value) and one cap is a double cap marked 1. on the bottom of the cap and on the schematic, what's the purpose of the decimal point (.) after the 1 on the double cap? I'm assuming it's a 1 MFD capacitor which if that's the case why bother with a decimal point after the 1 on the capacitor markings?

Also how would I restuff the 1 MFD bypass caps? I ask because I think a 1 MFD 630 VDC film cap is going to be too big of diameter to fit inside the can, let alone two of them.

Also as far as the .5 MFD caps go, I'm assuming a .47 MFD 630 VDC cap will work fine in its place?

Also I was wondering how I would go about handling the wiring going to the RF bypass caps because while the rubber insulation of the wiring is still intact and isn't falling apart, it is very brittle to the point that just moving the wires just slightly causes the rubber insulation on those wires to crack and chip off the wire which if I'm going to restuff those bypass caps I would have to move those wires and I don't want to have to replace any more wiring than I have to in this radio to get it up and running.

I'm not sure on the cap values. It's possible the double cap marked 1. is the total for the two .5 mfd combined, but that's just a hunch. You need to remember that back when these things were built the technology was still very experimental in nature. Personally I would try to baseline the radio using a dim bulb tester, then divide and conquer one component at a time. A complete strip down will only introduce more unknowns. I'd begin with the 80 rectifier removed, testing the transformer with only the filaments of the other tubes installed. Then with the 80 still removed measure between each of the two high voltage wingdings to ground. Next the 80 goes back in to see if the B+ comes up without drawing too much current. Start with a low wattage bulb and work your way up. As long as you limit the current you can't get yourself into too much trouble. At some point you'll have a better idea of where the problem areas are. I agree with leaving the wiring alone until you get all the other bugs worked out, and then only replacing a section at a time with testing in between.

[Kevin Kuehn]

Forgot to mention..I honestly can't think of any good reason you'll need film caps rated for 630v for bypass in this radio. Folks use them simply because they have them on hand and the rational better safe than sorry. I'll be surprised if the B+ swings above 250v for more than a couple seconds on power up. It should settle out around 170v at the second filter cap. The 71 output tubes had a 180v max design value, which I doubt they exceeded.

[vortalexfan]

Originally Posted by Kevin Kuehn

Forgot to mention..I honestly can't think of any good reason you'll need film caps rated for 630v for bypass in this radio. Folks use them simply because they have them on hand and the rational better safe than sorry. I'll be surprised if the B+ swings above 250v for more than a couple seconds on power up. It should settle out around 170v at the second filter cap. The 71 output tubes had a 180v max design value, which I doubt they exceeded.

OK, so maybe a 250vdc film caps for the bypass caps would be acceptable then? Those would be much smaller and would probably fit into the cans better than the 630vdc ones.

[Kevin Kuehn]

Originally Posted by vortalexfan

OK, so maybe a 250vdc film caps for the bypass caps would be acceptable then? Those would be much smaller and would probably fit into the cans better than the 630vdc ones.

Probably. But once you get that power supply operational and measure we'll know more precisely.