Re: K3 Beta firmware rev. 2.82

Posted by Julian, G4ILO on Feb 15, 2009; 5:22pm
URL: http://elecraft.85.s1.nabble.com/K3-Beta-firmware-rev-2-80-Improvements-to-AFSK-A-DATA-A-SSB-AM-FM-DVR-tp2305650p2330557.html

Guy, K2AV wrote

Taking the DATA A readings below at face value, the more than 2 db bump
around 1000 Hz is rather startling. I'm not sure what could cause that, but
at least to me that seems to be screaming for an explanation.  There's an
old fireman's adage "never go past fire" to keep from being trapped by fire
closing around behind.

Is there any point at discussing any more subtle issues until we know why
there's a 2 db bump in the middle of an expected flat DATA A bandpass?
Everything from test equipment to meters would be in play until ruled out.

I'm glad you asked that because I've been thinking about the same question. I have the 5-pole 2.7KHz filter and I observed the same peaks at 1000Hz and 2400Hz as Joe, who made those measurements. I guess he has the 5-pole filter too. It would be extremely interesting if someone with an 8-pole filter could run the same test and post the results to see whether there is less variation across the passband.

I would not be overjoyed to have to splash $125 to solve the problem, but it might be better than the alternatives.