[Elecraft] Unexpected use for a P3

[Chuck Guenther]

I've been spending the winter on 160 meters with my Cushcraft MA160V
top-loaded vertical antenna.  This antenna has been surprisingly effective
for such a short (approx. 36 feet) vertical.  I have a decent, though by 
no means
exceptional, ground system.  The usable bandwidth is on the order of 20 KHz,
and I carefully tuned it for a center frequency of 1820 KHz, positioning 
me for
CW DX fun on Top Band.

Since I obtained the P3 last Fall, I've noticed that I can see the 
rolloff characteristics
of my antenna simply by looking at the display with band noise.

We had considerable freezing rain and sleet, followed by snow here in 
St. Louis
in the past couple of days.  The top loading elements (coil and top-hat 
capacitance)
have a thick coating of ice on them.  The other night, I turned on my K3 
and P3 and
was prepared for listening for DX at sunset when I noticed the P3 was 
indicating a
frequency response rolloff far below what was normal.  In fact my 
antenna had made
a QSY right out of the band to a new center frequency of roughly 1770 
KHz!  Even at
the 1800 KHz band edge my SWR was about 5.5:1.

Having used this and other top-loaded verticals, I had experienced 
shifts of 15-20 KHz
due to icy conditions previously.  But never a 50 KHz shift!

I tried using my MFJ-259B Antenna Analyzer to check the resonant 
frequency and
bandwidth of my antenna, only to discover the lower limit of the 
analyzer is 1800 KHz.

Now, I'm waiting for some of the ice to melt or evaporate from my 
antenna so I can use it
again.  So I'm watching band noise on my P3, waiting for the resonant 
frequency to
come back up.  Already today, it has moved up about 10 KHz (even though 
the temperature
remains below freezing).

I just thought I'd point out this aspect of the P3 (or other panadaptor 
frequency displays) for
indicating the frequency response characteristics of high-Q antennas.

73,
Chuck Guenther  NI0C