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Re: [TowerTalk] Slick New Toy

To: k4to@arrl.net, herbert.schoenbohm@gmail.com
Subject: Re: [TowerTalk] Slick New Toy
From: "Richard (Rick) Karlquist" <richard@karlquist.com>
Date: Fri, 30 Nov 2018 07:02:45 -0800
List-post: <mailto:towertalk@contesting.com>
The 2 port version output level is only -17 dBm, which is
also the likely level for this version.   This is only
56 dB over S9. That does not bode well for BCB interference.
I could try my 2 port unit on my 90 foot vertical to see
how it fares.  I am 6 miles from a 50 kW station on 1140 kHz.
IIRC, it comes in at something like 80 dB over S9.

My AA-55 Zoom is bulletproof on the vertical.  Its output
level is over 20 dB higher than the VNWA.  Horses for courses,
as they say.

Rick N6RK

On 11/30/2018 6:01 AM, Dave Sublette wrote:
I meant -- how does the VNA work in the presence of strong AM signals.  My
vertical has worked great when used as an antenna on 160 for the past 30
years.  I know how the vertical works.

K4TO

On Fri, Nov 30, 2018 at 8:17 AM Herbert Schoenbohm <
herbert.schoenbohm@gmail.com> wrote:

I am within 3 miles from a 5KW AM station on 970 kHz without a problem.  I
do pick up the second harmonic on 1940 but never go that high in the band.
You may have second or third harmonic IX but that depends on the AM
frequency.  If the AM station, for example, is on 610 kHz 1830 kHz will be
bad for you for 5 kHz each side of their harmonic.

Herb Schoenbohm, KV4FZ

On Fri, Nov 30, 2018 at 8:50 AM Dave Sublette <k4to.dave@gmail.com> wrote:

Any info on how it might do on a quarter wave vertical for 160, operating
within two miles of an AM broadcast station?

Dave, K4TO

On Fri, Nov 30, 2018 at 4:28 AM Jim Brown <jim@audiosystemsgroup.com>
wrote:

Here's another nice new toy from DL-land by way of the UK. The designer
is DG5MK.

https://www.sdr-kits.net/VA5_Page

$235 got the analyzer and a better quality cal kit shipped to my door
just before CQWWCW. The better Cal kit was $20 of that cost. It took
less than two hours to put it together (as I get older I get slower).
It's a single-port true vector analyzer, and runs either stand alone on
two internal AAs or from VNWA software via a USB port. Decent build
quality, BNC is soldered to the board and bonded to the case at the
point of entry. The case is a 2-piece metal clamshell, screwed together
at four places. In other words, it's well shielded and has no Pin One
Problem!

There's a beautifully printed manual that covers building and operation,
with excellent color photos. Text is excellent in the building section,
pretty good in the button-pushing area, a bit weak in the concepts area,
and badly disjointed to point of being awful in its description of
calibration. The latter is a big deal, because it's the first thing you
do once you turn it on!

As near as I can tell,when running from VNWA software (FREEWARE), it can
do almost everything the VNWA can do with S11 (single-port)
measurements, except that choices of sweep rates and dwell time at each
data point are a lot more limited. That means I can use the excellent
TDR function built into the VNWA software! I don't know yet if I can
import complex data made stand-alone. BTW -- the measurement plane is at
the end of a 5 ft piece of RG142 from my stash. I find that a convenient
length for getting to where I can measure antennas from my shack.

This box is designed to be the one you use in the field and at the top
of the tower, but with the VNWA software, you can make measurements in
the shack, including TDR, then export antenna data to SimSmith to
transform it to the antenna ffeedpoint, then use SimSmith to design
matching networks and compute  loss in the feedline and matching
networks!

This is a VERY nice unit, and a real bargain!

73, Jim K9YC


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