Philco 7170 AM/FM generator transformer - Printable Version
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Philco 7170 AM/FM generator transformer - bakerm - 07-06-2017
I am restoring a Philco signal generator and the modulation transformer has an open secondary. The part number is 32-9610. Anyone possibly have one or know where I might get a replacement?
Thanks
RE: Philco 7170 AM/FM generator transformer - Radioroslyn - 07-06-2017
Hi and welcome to the Phorum,
Well I have a couple of answers for you.
Try and find a parts unit w/a good transformer.
If you like experimenting you can replace it with a tube type interstage transformer (single plate to p/p grids). Plate side (red and blue wires) go to the osc grid and gnd. Green wires are the two ends of the winding black is the tap. These go to B+, switch, and cathode follower plate. You may have to play w/the phasing to get it to oscillate. By changing the value of C-112 it will change the frequency of the audio tone of the audio oscillator.
GL
RE: Philco 7170 AM/FM generator transformer - klondike98 - 07-06-2017
Welcome to the Phorum!
RE: Philco 7170 AM/FM generator transformer - bakerm - 07-06-2017
Thanks
RE: Philco 7170 AM/FM generator transformer - Radioroslyn - 07-06-2017
So how's things over by the Grottoes? Was out there abt 40yrs ago. I'm a native Md'er. Hope I didn't scare you away w/ all that technical stuff.
RE: Philco 7170 AM/FM generator transformer - bakerm - 07-08-2017
Grottoes are still going strong. I've been trying to look into interstage transformers. The schematics list the primary and secondary resistances. Are they DC resistance and not impedance? I found one I thought but the DC resistances were very low.
RE: Philco 7170 AM/FM generator transformer - morzh - 07-08-2017
They are just that, DC resistances. Impedances depend on what speaker there is and turns ratio. Plus, on the lesser degree, on the stray inductances.
RE: Philco 7170 AM/FM generator transformer - Radioroslyn - 07-08-2017
Mike, No spkr here it's used in a signal generator. Pri is the feedback winding for the tone osc. Secondary couples the tone to the buffer/amp tube tube to achieve modulation.
Did see an inexpensive one at AES but not sure if the secondary winding can handle the plate current from the buffer tube.Primary is good for 10ma which is fine for the audio osc side. Also the DC resistance can vary depending on the wire size. You can't count on the pri and sec being wound w/the same size wire. Resistance means very little when looking for a replacement transformer.
RE: Philco 7170 AM/FM generator transformer - bakerm - 07-13-2017
I replace with a transformer and now the rf works - 1.5 p/p output and is close to dial settings.
Audio oscillator doesn't oscillate. You mentioned playing with phasing - not sure exactly what you mean. help?
RE: Philco 7170 AM/FM generator transformer - Radioroslyn - 07-13-2017
You can change the phasing by switch the two wires that go to the grid and ground around the other way.