[TowerTalk] Slick New Toy

[Wes Stewart]

By two-port version I think you mean the SDR-Kits VNWA (DG8SAQ); the FA-VA5 
(https://www.youtube.com/watch?v=X8Z7veGV57o) is an entirely different animal by 
a different designer (both Germans however).

I have both, the VNWA for a year or two and the FA-VA5 for a couple of months.  
I also have an original N2PK, the guy that started these things, a Rig Expert 
AA-55 Zoom and just leaving US Customs, an FAA-450 by EU1KY.

I also have a 50KW BC station on 1550 kHz, about 5 miles away. On my inverted-L 
they are S9+70dB (~-3dBm) on my calibrated K3/SDR-IQ combo.  I can use any of 
these instruments to measure the antenna without issue as long as I avoid 
sweeping through the BC band.

Wes  N7WS


On 11/30/2018 8:02 AM, Richard (Rick) Karlquist wrote:
> 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 at 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 at 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 at 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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>>>>>
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