Monday, August 22, 2005 Zulu
K2 BFO Range

I had trouble reaching 1000Hz on the RTTY reverse BFO filter on my K2, and that's the normal filter on the high bands, so when 15M was open I was inconvenienced.

After a mail exchange with Gary AB7MY of Elecraft I received a 2.7pF NP0 capacitor and put it across the crystal junction and L33 to ground on the bottom of the RF board. That lowered the bottom end of the BFO from 4913.22KHz to 4912.36KHz, and without affecting the top end. That was enough to let the BFO reach 1000Hz center frequency for all 4 filters in both R and R-reverse modes.

I tried lifting the resistor on L33 and making sure it didn't short any turns first. Gary said it was probably the crystal batch if I had all the parts right and L33 wasn't shorted.

I hadn't realized you can easily read the BFO range without going into CAL FIL, but it's there in the manual: Enter CAL FCTR and press BAND + for the high end, and BAND - for the low end.

- posted by Leigh @ 03:35 z
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