89 oscillator check - Printable Version
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89 oscillator check - baspas - 01-22-2010
I removed the oscillator coil and baked at 200 degrees for 30 min. I cannot see any breaks in the winding but I'd like to test it further. Is there some sort of Ohms test I could do between the five soldering lugs and the wire to the top of the tube? Where should I get readings and what? thanks.
Re: 89 oscillator check - baspas - 01-22-2010
O.K. if I'm reading this right I should get 5.2 Ohms between the lugs for the small outer winding. The first two clockwise from the clamp and connecting between the 77 tube and a cap and resistor. Right? I get nothing. Any pointers on how to rewind and what to use? Thanks again.
Re: 89 oscillator check - Carl Travis - 01-22-2010
Chuck has coil winding info on has site, but no specifics for the model 89:
http://www.philcorepairbench.com/tips/svctip36.htm
Re: 89 oscillator check - Radioroslyn - 01-22-2010
The winding in question connects from pin 5 of the#77 tube (cathode) to the cap and resistor in parallel. Should measure on the order of a few ohms. Bad ones will measure a few 1000 ohms. For winding details see the Philco Model 80 post.
Terry
Re: 89 oscillator check - baspas - 01-23-2010
Yeah but what gage wire do I use on an 89 primary coil?
Re: 89 oscillator check - Radioroslyn - 01-23-2010
If you mean the feedback winding (cathode) anything from 30 to 36g is fine. It's not very critical as it doesn't determine the frequency. It just determines whether it oscillates or not.
Terry
Re: 89 oscillator check - baspas - 01-23-2010
Thank you!
Re: 89 oscillator check - Ron Ramirez - 01-25-2010
I use 38 gauge as that is what was used originally. Most have 28 turns although I have found some that have 24 turns.
Wind the winding clockwise, as you are looking at the bottom of the coil where the terminals are.