To elevate it, use the force. 🙂
73
John Denison
KD5YOU
On 6/19/2024 8:24 PM, Andre Pollard via BVARC wrote:
Thanks all for the feedback. No chance to work on it today, even if
the weather had cooperated.
I can get it to work fine on 20M and up, and since the trip starts
soon, I'm going to try it again when we get back. Going to try another
testing location to rule out interference that only seems to affect
40M, since the current location is fairly near the house (stucco with
metal lath), and buried electric lines. Also will try different coil
settings and grounds. I will try to elevate it too, but since this is
my hiking antenna I'm not sure I want to add a tripod LOL.
Andre
W4SFZ
On Wed, Jun 19, 2024 at 4:09 PM John Denison via BVARC
<bvarc@bvarc.org> wrote:
Hi Andre
I was going to mention the 33' counterpoises, but I see that you
have done that already. I've used a single counterpoise on 40
meters with various coil antennas. One thing I didn't see in any
of the emails is... where are you setting up your antenna? Is
there anything metallic nearby?
I have a Wolf River Coils Take It Along mini which is good for 40
meters and up, and I found that I can tweak the resonant frequency
by rotating the sleeve around the coil rather than just moving it
up and down. I use either the stock WRC telescopic whip or a
Buddipole extended length whip used for 80 meters. Both are
roughly 10 feet long.
I typically achieve better results with vertical antennas when
they are elevated above the ground. i.e. 4-5 feet vs .5 foot above
the ground, though I was never able to get any results comparable
to an inverted V. With a manual tuner I was able to make the
transceiver happy while still being able to use the antenna to
some degree of success, but it took a steady hand and very
miniscule changes in the capacitance knobs.
73
John Denison
KD5YOU
On 6/18/2024 4:19 PM, Andre Pollard via BVARC wrote:
I need one of our antenna gurus to give me some input-
I have an 18'-4" telescoping antenna I have been using when
camping. By adjusting length, I can get it to tune at <1.5 SWR on
all bands 20M and above. So far so good, but when do we ever
leave well enough alone.
I'm getting ready to travel for a while, and wanted to extend the
range down to 40M. So I used the calculators at Coil-Shortened
Vertical Antenna Calculator (66pacific.com)
<https://www.66pacific.com/calculators/coil-shortened-vertical-antenna-calculator.aspx>
to
determine the necessary coil. It said I need 4.9 mH. I made the
coil per the calcs one the same site, using a 1.9 inch diameter
PVC pipe. I'm running it bottom-loaded.
By tapping the coil a couple of turns down, I can get it to tune
to 7.2 mhz, but the SWR is >6. If I put my hand very close to the
coil , the frequency shifts (expected), and the SWR drops to 1.2.
So I tried adjusting the length and tapping different turns,
never better than 4 SWR on any frequency around 7 mhz. However,
if I get my hand near the coil, SWR drops.
Thinking this meant I needed capacitance, I tried a hat to the
whip, with several different designs and sizes. Changes
frequency, but horrible SWR still.
Bypassing the coil I can adjust the whip and get great SWR on 14
mhz and above. So, I don't think it's a problem with the coax (20
feet of RG8X) or nanoVNA.
Google shows up all sorts of sites showing making a coil loaded
shortened vertical like i'm trying. None mention the issue I'm
seeing as a problem.
I'd appreciate any input, I've been 'learning' on this for a
couple of days now and haven't gotten it to work yet.
Thanks,
Andre
W4SFZ
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