On Dec 7, 2005, at 12:17 AM, Mark Schreiner wrote:
If I have a great Rx only antenna won't I be able to hear many more
stations that I probably won't be able to work?
Yes.
I wasn't running QRP in the ARRL 160m contest, I was running a full
100 watts from the K2/100. Still, there were several stations I could
not contact, even though they had pretty good signals into my area.
W7SE in WY was one of them. I heard him both nights, and spend
several minutes calling him, but barely got any response from him.
There's certainly a danger in being a "rabbit" station (All ears, no
mouth) when you use a good Rx antenna. The thing with the low bands
is that it is usually the noise that limits what you can work. Guys
will hear you, but you won't be able to copy them. (In retrospect,
maybe some of those guys are running QRP....)
With my Carolina Windom at about 45' that I used on both Tx & Rx I
was barely able to copy him initially, then as his signal finally
improved so that I could copy so-so, good enough to copy his
callsign after enough times of him calling CQ or a few people now
and again answering him (while there was several big pileups a few
kHz above).
Some 15 or so years ago, when Packet was very, very new, I remember
logging in to a local packetcluster node and seeing spots for
stations on 160m. I switched to my 300 foot long, 15 foot high random
wire and tried to chase some of the spots. I tried several, but could
hear nothing. Finally, I saw one spot with the notation "LOUD!!!".
This guy, I could just barely hear.
My problem wasn't that I needed a good receiving antenna -- I just
needed a good 160m antenna. That Carolina windom may be a pretty good
compromise all-band antenna, but its not going to be very effective
for 160m, particularly at just 45 feet high. (That's what 13m?)
So, while it may be interesting and educational to put up a receiving
antenna, my advise to you would be to try and put up a more effective
160m antenna. One of the more popular simple antennas is the Inverted-
L. 140 feet of wire, running vertically as high as you can and then
horizontally. Fed against as many 100 foot (or so) radials as you can
lay down, it would be a pretty effective antenna.
Horizontal antennas aren't that effective for 160m. W8JI has made a
long study of this. In addition to several verticals, he also has a
300 foot high full size dipole for 160m. 300 feet may seem high, but
consider that it isn't even 90m tall. It's just over 1/2 wavelength
high -- which is where dipoles start to become really effective
antennas. Tom has related that he almost never finds the dipole to be
more effective than the verticals for DX, except for some really
oddball openings around sunrise.
The key dimension for any horizontal antenna is the height above
ground in wavelengths. That Carolina windom probably started to
really shine on 20m and higher. It's just not practical to place 160m
antennas this high. Hence - verticals.
It was about a 15 to 20' vertical with a large loading coil about
2/3 of the way up. Not sure where this was supposed to work but I
put it on a homebrew tripod sitting on a 2nd floor porch and ran a
single #8 or #10 ground wire (Aluminum from RatShack) to a copper
ground rod made of 4 to 6' of 3/4" copper pipe.
That's the thing about antennas -- EVERYTHING WORKS. Even dummy loads
can be used to make contacts. But you'll work a lot of stuff a lot
easier with more effective antennas.
Bill Coleman, AA4LR, PP-ASEL Mail: [EMAIL PROTECTED]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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