[Lowfer] MP, MP, and More MP

[JD]

Was anyone else on air in the vicinity of 137.78 tonight after about 0400, 
or was MP all alone?

After envying all the wonderful screen shots of the past couple of days, I 
ventured out into the field tonight despite severe thunderstorms in the 
western part of the state and a nasty cold storming inside my head.  On the 
plus side, the temperature was pleasant and the tendons I injured in my hand 
last week felt almost human again...but I had to wait until the wind (read: 
blowing dust) died down, which was around 11 PM CDT.  The HiFERs were gone 
by then, I saw no one at all on 495 or 185.3 kHz, and only Mitch seemed to 
be present on 2200 m.

None the less, I used the opportunity to experiment with my clipper circuit 
together with my new antenna buffer amp.  We all know it is possible to have 
too much of a good thing, and that's even true of RF reaching our receivers. 
The buffer has unity voltage gain, but delivers the full open-circuit 
voltage of the antenna to a run of 50 ohm coax and thence to the receiver 
input.  That represents considerable _power_ gain, given the high reactive 
impedance of a 15 meter vertical antenna at LF.  To my surprise, the 
previous mismatch had apparently resulted in over 40 dB of needless 
attenuation at 1750 meters, and even more at 60 kHz.  Remedying that 
mismatch makes it necessary to use the input attenuator from time to time, 
or else the "new, improved" static causes the AGC to modulate the desired 
signal and give it lots of random-ish sidebands.  Without the buffer, the 
static was not bad by previous standards...only up to around S5.  But with 
the buffer, it was between +20 and +30 on peaks tonight, despite the 
considerable distance to the storms.  I found that I get best results with 
static peaking around S9, which seems to be a breakpoint of some sort for 
the AGC time constants in the Kenwood.

During the day, I will stitch together captures illustrating the results and 
try to compress the JPEG enough to pass through the reflector.

Can't wait to try it in the quiet of winter!

John