Model 16 Oscillator Failure

Model 16 Oscillator Failure

On some models of the Philco 16 All-wave Receiver, difficulty was experienced with failure of the set to oscillate [the local oscillator/mixer stage] at the low frequency end of the two top bands.

Investigation in one case showed a high resistance between the rotor plates of the tuning condenser and the chassis. Although there are several grounded points for this connection, a small amount of corrosion had set in and introduced a relatively high resistance. By tightening the screws, this condition was entirely eliminated and the set played correctly.

In another case, it was found that corrosion had become embedded under the bakelite washer on the gang compensating condenser at the front of the chassis (10.8 megacycle adjustment). By removing this washer and cleaning it thoroughly, the trouble was entirely eliminated. It was, of course, necessary to readjust the short-wave compensating condenser.

On one Model 16, it was found that the antenna series condenser No. 5 in the wiring diagram of Philco Service Bulletin No. 165 was open. Another set had an open coupling condenser in the plate circuit of the oscillator, No. 26, Service Bulletin No. 165. A Model 16 which was weak on the low frequency end of all bands was corrected by reducing the value of the resistor in series with the oscillator plate (No. 27) from 50,000 ohms to 30,000 ohms.

From the Philco Serviceman – May, 1934.