[TowerTalk] NCC-1 and ARAV2-1P verticals observations

[Tod -ID]

Hi Billy:

I can't give a good report comparing the K9AY setup of last year and the new
NCC-1/ARAV2 setup. I had to take down the K9AY from its previous location
and it is planned for erection next week off in my side yard [after the last
lawn cutting is completed]. 

The biggest change is that I was not able to quickly switch between four
choices and see which one was the best for the station of interest. The K9AY
with its two loops and four directions was nice. That said, I did not feel I
was missing much, if anything, with the current RX combination. Still, until
I can do an A-B test I really have no solid evidence that one is better than
the other.

I have not measured the distance directly since a sizeable irrigation canal
runs between the TX vertical and the RX system and it was filled with water
until today. I estimate that the distance is about 120 feet from the TX
antenna to the nearest ARAV2 whip. The other whip is probably 140 feet away
from the TX antenna.


My top loaded vertical was made from an old HyTower. I removed the stubs and
connected the stinger to the main tower body. Then I extended the stinger so
the top was 57 feet above ground. Finally, I ran a horizontal top loading
wire 20 feet from the stinger tip to a Unadilla 80 meter trap. On the other
side of the trap the wire continues another 40 feet or so and then goes down
toward the ground. The feed point is at the base since the HyTower is
insulated from ground. The overall length of the wire is selected to produce
a resonance at 1900 kHz with the trap in place. There is also a resonant
point at 3600 kHz. From 3500 to 3700 the SWR is 1.7:1 or so. At 1800-1900
kHz the SWR is about 3:1 so one needs a tuning network someplace before the
final to get suitable matching. Since I use 7/8" CATV to make the 130 foot
run to the vertical I decided to do the matching at the station rather than
at the base of the tower. The added loss in 130 feet of 7/8" CATV due to an
SWR of 3:1 is too small to be noticed.

Tod, K0TO



> -----Original Message-----
> From: Billy Cox [mailto:aa4nu at ix.netcom.com] 
> Sent: Sunday, October 21, 2007 4:05 PM
> To: Tod -ID
> Subject: Re: [TowerTalk] NCC-1 and ARAV2-1P verticals observations
> 
> Tod ... great post! How does this compare  with the K9AY 
> setup you had before?
> 
> The top-loaded XMIT vertical is how tall?
> 
> How far are the 2x  ARAV-2s from your XMIT vertical?
> 
> TU es 73 de Billy, AA4NU
> 
> 
>