01-04-2022, 11:46 AM
The transformer has been installed.
[Image: https://live.staticflickr.com/65535/5179...731d_c.jpg]Adding FM to a Philco 118 by Steve Davis, on Flickr
The ground connector is never used on this radio so, I converted the original ground connector to the FM antenna connection by drilling the hole larger and using the insulating bushing from a parts chassis.
[Image: https://live.staticflickr.com/65535/5179...0c79_c.jpg]Adding FM to a Philco 118 by Steve Davis, on Flickr
It's time for the test. The first step is to calibrate the tuning, this is really simple. With the radio turned on, the band switch is set to the new FM position. The dial is turned to a point near the low end of the scale, the calibrate button is gently pushed and released. Now, the dial is turned to a point near the high end of scale and the calibrate button is pushed again. That's it, the radio is ready to tune in FM stations and tune in FM stations, it did! All I can say. This thing is awesome! Stations come in crystal clear and the sensitivity is excellent. Using a wire about 2 1/2 feet long for the antenna, it picks up 30 or more stations across the dial.
Some thoughts and observations
The module uses one section of the radio's original tuning capacitor to select stations so, to keep the AM working, some sort of switching arrangement is needed to switch the tuning cap and the audio. This could be as simple at a DPDT switch or maybe a DPDT DIP relay mounted directly to the tuning cap. I chose to replace the band switch to keep all switching on one control. The AM did require realignment. The tuning cap wire to the module needs to be as short and direct as possible. One of the first things I noticed was any movement of the chassis would cause the FM to go off station. The shadow meter had to be removed to access the trimmers for the AM alignment. While on FM any movement of the detached shadow meter would cause Fm to go off station. Turning the chassis over I could see the shadow meter wires were rubbing the tuning cap wire to the module. I never used the SM because lamp socket has been damaged so, I just removed the SM and wiring and adding a resistor. I also used hot glue to immobilize the tuning cap wire. This totally eliminated all problems with the tuning. The next thing to do is create a log to locate the FM stations. There may be 5 or 6 stations that I might listen to, I will note where they appear on the AM scale. I will continue to use this chassis as is in my shop, I also plan to modify another radio for use in my house. To anyone thinking about doing this mod, I highly reccomend it.
Steve
[Image: https://live.staticflickr.com/65535/5179...731d_c.jpg]Adding FM to a Philco 118 by Steve Davis, on Flickr
The ground connector is never used on this radio so, I converted the original ground connector to the FM antenna connection by drilling the hole larger and using the insulating bushing from a parts chassis.
[Image: https://live.staticflickr.com/65535/5179...0c79_c.jpg]Adding FM to a Philco 118 by Steve Davis, on Flickr
It's time for the test. The first step is to calibrate the tuning, this is really simple. With the radio turned on, the band switch is set to the new FM position. The dial is turned to a point near the low end of the scale, the calibrate button is gently pushed and released. Now, the dial is turned to a point near the high end of scale and the calibrate button is pushed again. That's it, the radio is ready to tune in FM stations and tune in FM stations, it did! All I can say. This thing is awesome! Stations come in crystal clear and the sensitivity is excellent. Using a wire about 2 1/2 feet long for the antenna, it picks up 30 or more stations across the dial.
Some thoughts and observations
The module uses one section of the radio's original tuning capacitor to select stations so, to keep the AM working, some sort of switching arrangement is needed to switch the tuning cap and the audio. This could be as simple at a DPDT switch or maybe a DPDT DIP relay mounted directly to the tuning cap. I chose to replace the band switch to keep all switching on one control. The AM did require realignment. The tuning cap wire to the module needs to be as short and direct as possible. One of the first things I noticed was any movement of the chassis would cause the FM to go off station. The shadow meter had to be removed to access the trimmers for the AM alignment. While on FM any movement of the detached shadow meter would cause Fm to go off station. Turning the chassis over I could see the shadow meter wires were rubbing the tuning cap wire to the module. I never used the SM because lamp socket has been damaged so, I just removed the SM and wiring and adding a resistor. I also used hot glue to immobilize the tuning cap wire. This totally eliminated all problems with the tuning. The next thing to do is create a log to locate the FM stations. There may be 5 or 6 stations that I might listen to, I will note where they appear on the AM scale. I will continue to use this chassis as is in my shop, I also plan to modify another radio for use in my house. To anyone thinking about doing this mod, I highly reccomend it.
Steve
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