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Monday, November 26, 2007

More NC-57

I added a Heathkit QF-1 Q-Multiplier ( ) to my NC-57. The QF-1 provides additional selectivity or signal rejection as desired. It was marketed by Heathkit starting around 1956 and was a fairly common accessory. It requires a connection to the IF stage plus B+ and filament voltages available at the NC-57 accessory socket.

I found this to be a big help. The QF-1 effectively eliminated the CW audio image (ie. a readable signal each side of zero beat) common in receivers that don't have a crystal filter. Eliminatling the audio image eliminated half the QRM on the band.

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