07-25-2008, 11:13 PM
The 37-690 and 38-690 both have filters which limit the top end audio response to 10 kc. The filter in the 37-690 is adjustable; the 1938 version is not.
The original intent of the filter was, indeed, as a "whistle" filter; to prevent adjacent channel interference. The filter is in the audio section, though; the best way to prevent adjacent channel interference is to limit the bandwidth. This is what the Fidelity-Selectivity control would do.
In addition, there is one bakelite block in the upper chassis of the 38-690. That bakelite block is NOT a capacitor!!! Instead, it contains the coils for the set's 10 kc filter.
The original intent of the filter was, indeed, as a "whistle" filter; to prevent adjacent channel interference. The filter is in the audio section, though; the best way to prevent adjacent channel interference is to limit the bandwidth. This is what the Fidelity-Selectivity control would do.
In addition, there is one bakelite block in the upper chassis of the 38-690. That bakelite block is NOT a capacitor!!! Instead, it contains the coils for the set's 10 kc filter.
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Ron Ramirez
Ferdinand IN
