Open rf choke in Model 48-482 - Printable Version
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+--- Thread: Open rf choke in Model 48-482 (/showthread.php?tid=6063)
Open rf choke in Model 48-482 - 57studebakersilverhawk - 02-24-2013
This is my first post, although I have been using the Philco Phorum as an information source to assist in radio restorations for some time. Thanks to all contributors.
I restored a Philco Model 48-482 about a year ago and it has been playing very well until recently when reception problems began on the FM band. At first it an intermittant problem and eventually became no reception at all.
By following the Riders trouble shooting instructions I have found that the L300 rf osc choke (part #32-3352) associated with the FM1000 tube is open. When I bridge the choke with a piece of wire the FM band functions but the fidelity is not good. Is it possible to repair this part? If not what can I use as a replacement. Thanks for your help.
RE: Open rf choke in Model 48-482 - Radioroslyn - 02-26-2013
After looking and scratch my head it looks like a quadrature detector. The cathode,control grid, and second grid act as an oscillator at the IF frequency 9.1 mc. L300 needs the be resonant at 9.1 to cause the oscillator to operate. I suspect that when you wired in your replacement it caused the FM1000 to conduct but not oscillate.
Terry
RE: Open rf choke in Model 48-482 - Radioroslyn - 02-28-2013
Can you post or send me a pic of??
Terry
RE: Open rf choke in Model 48-482 - 57studebakersilverhawk - 02-28-2013
Thanks for the information Terry. I searched the Phorum one more time and found someone else had the same problem with the RF choke opening up. Their solution to the problem was melting the wax off of the choke and repairing the break in the wiring. I tried the same thing and was also lucky in that the break in the choke wire was located where it could be repaired. After making the repair and recoating the choke with wax I reinstalled the choke and now the radio is playing perfectly on the FM band. Thanks again for responding.
RE: Open rf choke in Model 48-482 - Radioroslyn - 03-01-2013
Great!!! Now I can sleep again!!
Terry