Hello TopBanders,
I recently decided to finally try the Topband and would like to be up and
running for the Stew Perry Contest in December. As a VHF / Microwave guy,
the grid square exchange appeals to me as Im on familiar ground there, but
that is as far as it goes..oh and digging weak CW signals out of the noise
is also familiar..but boy is there a lot of noise!
I would like to ask a few questions on the antenna I put up and get some
suggestions on how to improve it. Keep in mind I have limited experience
here so please forgive the simplicity of the situation.
I have a SteppIR Big IR vertical in the lot, which I have optimized for 40M
with 60+ radial at 40 feet long.
>From there, I disconnected the RG8 feed to the SteppIR antenna at the base
and connected to a long wire up to my crankup tower, the braid is connected
to my ground grid for the SteppIR vertical.
The overall wire length is about 125' - about 100' of it slopes up to the
top of the tower from a foot above ground, to about 55'. (approximately 30
degree slope up from horizontal) The other 25' slopes down from the tower
at about a 45 degree angle and is tie off by a long rope support. The wire
is insulated from the tower. This wire runs in a North - South
configuration.
I started out at about 140' of wire, and trimmed it back, but the best SWR I
could get was about 4.5 to 1 at 1.830 MHz. These measurements were taken
back inside the shack at the coax entrance. I was using an MFJ 259
analyzer. The analyzer said it had a 60 ohm R and zero X, which really did
not make much sense to me. As I tuned the MFJ down to about 1.75 MHz, the
SWR really did not change, but the R started to really get high, around 100+
ohms. I have ferrites installed at the SteppIR base coax feed end to keep
radiation off the feedline, but these I believe were only good to 40 or 80M,
I have to look into that.
I was using a FT-1000MP, and the tuner did indeed tune the antenna as it
was, but I don't think it liked it all that much.
The reason for feeding from the base of my SteppIR is that it is a
convenient spot, and if it works, one could use a simple coax relay to
switch between the vertical and the 160 M antenna. So if I could make this
work, that would be ideal.
I understand a sloper from the tower, with the braid connected at the top of
the tower would work too, but this was an easier solution at this point.
In addition, I have heard about shunt feeding my tower, but I have been
leery about that since I have transverters, pre-amps and microwave
amplifiers mounted up there. I don't know if those devices would be
affected by shunt feeding, but I opted not to go there as I have no
information one way or the other if my microwave stuff would be damaged. So
I errored on the conservative side and did not go there.
I heard lots of stations over the weekend, worked a VE5 and 6Y2?. Sunday
night I heard a few UA stations from EU, so that was encouraging, but the
QSB had them in and out. Last night I copied lots of code from W1AW, but
tons of QSB and signals were not all that good. So its hard for me to tell
if the antenna is really doing a good job or not, as I have no experience on
the propagation of the band and what really is good for signals.
So, that's it for now, Id appreciate any comments.
73
Mike King - KM0T
NW Iowa - EN13
www.km0t.com
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