On 03/03/2017 18:17, Clemens Heese wrote: > Somehow I have a similar issue. Using an SDR (RedPitaya) with a variable > gain amplifier as preamp (and a 30 MHz low pass). I am wondering how to > best set the preamp. Currently I have just experimentally set the gain > to get most decodes in 24h (weighted by my reference station)
Hi Clemens, empirical testing is hard to beat. Other than that I can't see any serious problem with the following approach: use a two way aerial coax switch with your aerial and a dummy load. Adjust the preamp gain to the minimum level where switching to the dummy load reduces the background noise. Turn the gain up a notch to allow for noise QSB. My thinking is that an amplifier is a source of noise which may be directly related to gain setting so using the minimum level that doesn't loose the band noise floor is probably best. I'm sure the EME operators will have more scientific methods for setting pre-amp gain. No doubt some will ask which end of the feeder the pre-amp is located. YMMV, 73 Bill G4WJS. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
