[hpsdr] A Mercury tail: A case for Alex

[a.groff]

       I have been using Mercury/Ozy/Pentalope for most of my day to day 
operation for the past few week.  Yesterday while listening on the 20 
meter band late in the afternoon, I noticed intermittent ADC overload 
indications and increasing 20 meter noise floor.  I have an external 100 
watt amplifier attached and was listening through the amps low pass 
filter attached to a multi-band vertical ( Hygain 620 AVQ - 20 thru 6 
meters).  After some tuning around, I found a fellow ham 4 miles away 
operating on 160 meter band.  I turned off the Mercury preamp control 
(i.e. enabled the input attenuator) and the ADC overload and increased 
20 meter noise floor when away.

      Its easy to forget that with no input selectivity, turning on the 
preamp to hear the weak ones on that higher bands also turns on the same 
preamp for all frequencies and increases the opportunity for ADC 
overload on all frequencies.

       I had though that the 20-6 meter vertical would not have been 
that efficient at 160.
       Although there are close to 50 hams in a 4 mile radii, none had 
previously given me any problems with overload on the Mercury or the 
Flex 5K.             
       With a high pass antenna tuner, half octave band pass input 
filters or ALEX, I most likely would not have had a problem.

Al, K0VM