10-23-2020, 11:15 AM
Hi. I'm doing a light restoration of a Philco 48-482 I inherited from my grandfather. It's a radio I fondly remember from my childhood, and it's exciting to get it working.
It receives AM ok, and the frequencies line up pretty well on the dial plate (after indexing the indicator.
However, while it's receiving FM pretty well also, the frequencies are way off. The actual frequency is around 1-2 MHz below the indicated frequency. I can't tune a station below about 90 MHz, as the tuning cap runs out of travel. It seems like it's some sort of zero offset problem, since the whole scale is similarly off.
For stations with a decent signal, the volume output is quite acceptable.
Is there a way to shift the alignment of the FM frequency response? I've seen the service manual's guidance for "FM alignment", but it is primarily talking about how loud, or clear, the signals are.
Any suggestions? Thanks in advance!
Jerry
It receives AM ok, and the frequencies line up pretty well on the dial plate (after indexing the indicator.
However, while it's receiving FM pretty well also, the frequencies are way off. The actual frequency is around 1-2 MHz below the indicated frequency. I can't tune a station below about 90 MHz, as the tuning cap runs out of travel. It seems like it's some sort of zero offset problem, since the whole scale is similarly off.
For stations with a decent signal, the volume output is quite acceptable.
Is there a way to shift the alignment of the FM frequency response? I've seen the service manual's guidance for "FM alignment", but it is primarily talking about how loud, or clear, the signals are.
Any suggestions? Thanks in advance!
Jerry
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