[NLRS] EN37 Weekend VHF results

[Dr. Gerald N. Johnson]

I discovered while doing my research on close spaced yagis that the back 
9 elements of a FO design do very well. 0.17 dB less gain on a 10' boom 
than M2 9 element on a 14.5' boom. And the 432 version I've built has 
come in with greater than computed gain at two CSVHF measurements. Makes 
me wonder a little about TEM's aged 432 K2RIW reference antenna that has 
thousands of miles on it traveling to conferences.

K1FO suggested such a short yagi from his design would not be good 
because he hadn't optimized it. I think the pattern is as good as the M2 
and as his well optimized antennas though I don't put a lot of emphasis 
out here near the Boondocks on front to back and front to side because 
QRM is not a problem and there's benefit to detecting signals out of the 
main lobe because signals are not there all the time.

I compared them in my paper which is on line at:
www.geraldj.networkiowa.com/papers/2012/HowCloseBa.pdf
Elevation patterns on the left, azimuth on the right in that paper 
because the mixed antenna elevation patterns were not symmetrical. See 
page 9 for this FO-9 comparison.

One antenna concept I've been considering for roving is to mount a chunk 
of plywood on the truck topper roof or car top carriers. Install a heavy 
duty lazy susan ball bearing in the middle, and a round chunk of plywood 
on that. Then antennas on that upper plywood, probably 3/4" exterior 
grade. Turning at the edge gives pretty good leverage for sharp 
microwave antennas, and I'd put spacer blocks that just cleared the gap 
aft, port, and starboard where I'd carry some plastic quick wood workers 
clamps to lock the antennas in a particular azimuth. And one or more 
such clamps would hold the array fixed in the least wind load direction 
for travel. I picked up a gaggle of such clamps on my way back from the 
UP last August and the heavy duty (1K pounds load rading) on my way home 
from CSVHF last July. Menards had a rebate on the clamps getting them 
down to about a buck each.

Here it was blustery on Saturday, started out warm and cooled rapidly, 
Sunday it wasn't blustery but snowed all morning accumulating maybe a 
half inch. I heard numerous 5s on 6m but usually only K5 was all the 
burst allowed. Worked most normal distances on 6m at least Seward NE to 
Moline, couldn't get UC to hear me, didn't put in much effort. Need to 
get up some antennas not shadowed by the terrain and the back yard 
machine shed with good feed lines. 4 Qs and 4 grids on 6, 3 each on 2 
and 2 each on 432. Hardly worth the postage or the time to copy to a 
paper entry.

73, Jerry, K0CQ


On 1/21/2013 10:59 AM, Zack Widup wrote:
>
>
> I never made it on. Saturday was out because I had other commitments. I
> planned on operating on Sunday if the weather cooperated but when I got to
> the hill the wind was so strong I couldn't even get the antennas up. Plus
> wind chill in that wind was way below zero. I just went back home.
>
> Funny thing is, the wind died down later when I was home. I might have
> managed 4 hours on Sunday but I don't know if it was worth it driving an
> hour each way and spending an hour and a half putting everything up and
> another hour and a half taking it down.
>
> I'm hoping the next vehicle I get allows me to quickly set up the antennas
> on it rather than putting masts, guy ropes, etc. out in a field. I'd still
> prefer the QRP Portable class rather than be a Rover. I'm going to build
> the K5GW 10-element Yagi on a 17 foot boom for 144 MHz. That should be an
> improvement on that band.
>
> 73, Zack W9SZ
>
>