[Elecraft] Filter alignment once again

[Bill Coleman]

On Apr 17, 2006, at 11:31 PM, Tom Hammond wrote:

> If the shapes of the LSB and USB filters are NOT opposite of each  
> other, the implication is that BOTH are on the SAME SIDEBAND,  
> rather than being on OPPOSITE sidebands.

This occurred to me, but since the BFO frequencies he listed seemed  
right, this didn't seem possible. That's why I thought there was some  
sort of other high-frequency attenuation going one. Ron hit it on the  
head - the caps across the headphone jack cause this rolloff.

> This can be confirmed by comparing either the DAC counts or the  
> FREQUENCIES of the BFO. If both sets of values (DAC _or_ FREQ) are  
> on the SAME side of the filter center frequency, then they're both  
> on the same sideband, though possibly not on the same exact frequency.

Yup. Made that mistake once myself.

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901