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Cap Values on 15X & Riders Error - Printable Version

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Cap Values on 15X & Riders Error - Phlogiston - 06-28-2014

http://www.nostalgiaair.org/PagesByModel/138/M0013138.pdf

The Riders manual is missing the cap values on the 15X. Not a big deal but it appears that at least 2 of the mica caps have become semiconductors - yes they leak in one direction only. Anyway they have an odd 2 dot value. They are part numbers 11 and 42 or 41. 11 tests at .01 but it would be nice to be sure.

Thanks

RE: Cap Values on 15X - Ron Ramirez - 06-28-2014

http://www.philcoradio.com/tech/images/15.jpg

(11) is 35 pF; (41) and (42) are both 110 pF.

RE: Cap Values on 15X - Phlogiston - 06-28-2014

Thanks Ron.

RE: Cap Values on 15X - GarySP - 06-28-2014

Ron, you either have a library the size of the library of congress for all the Philco information, or the amazing ability to pluck this info off the top of your head! It's mind boggling, and very much appreciated. Take care, Gary

RE: Cap Values on 15X & Riders Error - Phlogiston - 06-29-2014

My antenna was giving me a ground loop. Those caps are OK.

Riders says that the P-K voltage on the RF tube should be around 165 volts. I can see this in the 112 schematic since it has several resistors in the B+ but not on the 15. It is about 290V. Resistor 10 (160K) is right on as is cap 5 (.05uf).

The reason that I was looking at the RF amp is because cap 5 (the other half of a dual .05uf Bakelite block) is taking most of my signal to ground. Everything is fine with it out of the circuit, both in the local and distance settings.

??

RE: Cap Values on 15X & Riders Error - Ron Ramirez - 06-29-2014

I don't have the voltage chart near me right now, but the B+ at the RF plate should be at, or near, the same voltage as that on the plate of the 2nd IF tube with the local-distance in the "distance" position. The signal will drop with the switch in the "local" position since the RF tube's cathode is then connected to ground through (10), the 160K resistor. I would expect the RF plate voltage to be somewhat lower as well when measured between P-K in the "local" position as the Rider info calls for.

Could this be an effect of using a modern multimeter as opposed to the 1000 ohm/volt meters used in 1932?

Assuming both halves of (5) were replaced with new caps...the other (5) in the front end is an AVC filter cap.

RE: Cap Values on 15X & Riders Error - Ron Ramirez - 06-29-2014

GarySP Wrote:Ron, you either have a library the size of the library of congress for all the Philco information, or the amazing ability to pluck this info off the top of your head!

Aw, Gary, you're too kind. It just comes from years of studying this stuff. I don't claim to know it all...

RE: Cap Values on 15X & Riders Error - Phlogiston - 06-29-2014

Both of the caps are new and tested.

Yes there is some voltage difference with my new VOM but nor enough to account for the 165 - 290 volt difference. It is about the same as the 2nd IF.

There is about 30V to chassis ground in the local position and about 35V from K-Fil on the RF tube and about 15V on K-G.