[CQ-Contest] Slick New Toy
hfdxmonitor at gmail.com
Fri Nov 30 11:17:01 EST 2018
I purchased the VA4 just weeks before the release of the VA5. Kicking
myself one more time for the bad timing. LOL
The VA4 is great, the VA5 is even better.
I'm surprised this VNA does not get more 'airtime'.
73 de Vince, VA3VF
Here's another nice new toy from DL-land by way of the UK. The designer
is DG5MK. SDR-Kits is some hams in the UK that build and sell the
excellent DG8SAQ VNWA Vector Network analyzer and provide great support.
$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. I found
time to build it on Wednesday -- 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, the 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 stand-alone unit you use in the field and
at the top of the tower with no computer, but with the VNWA software
conneccted via a USB port, 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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