[TowerTalk] K9YC Choke Cookbook Question

[Jim Brown]

Thanks Maximo. I was not aware of it, but it's description is 
deceptively wrong. It's advertised as a Vector Network Analyzer, but the 
description says that its S21 measurements are scalar. So it's NOT a 
VNA. It's a Vector Impedance Analyzer combined with a swept generator 
and spectrum analyzer. The portability looks nice, but it's more than 
twice the cost of the VNWA 3e.

The VNWA 3e is a true VNA, and it can be set to work as a spectrum 
analyzer. It's built in the UK.

73, Jim K9YC

On Mon,2/6/2017 2:07 AM, Máximo EA1DDO_HK1H wrote:
> Regarding weapons of choice, I am not sure if you know this nice portable device:
>
>
> http://www.deepace.net/
>
>
> 73, Maximo
>
>
> ________________________________
> De: TowerTalk <towertalk-bounces at contesting.com> en nombre de Jim Brown <jim at audiosystemsgroup.com>
> Enviado: lunes, 6 de febrero de 2017 5:02
> Para: towertalk at contesting.com
> Asunto: Re: [TowerTalk] K9YC Choke Cookbook Question
>
> And with the easy availability of powerful test gear at relatively low
> cost, combined with AC6LA's fine Excel spreadsheets, it's easier than
> ever to get good data for VF and Zo vs frequency from a few measurements.
>
> The procedure is pretty simple. Make swept vector impedance (that is,
> complex, magnitude and phase) of a convenient length of the line, one
> with the far end open, again with it shorted. Export that data to the
> spreadsheet, which will then compute and plot curves of VF, Zo, and
> attenuation vs frequency. The AIM family of analyzers will do this, and
> I believe the SARK will too.  My weapon of choice is the VNWA 3e,
> designed by German university EE prof DG8SAQ and built by some hams in
> the UK.
>
> The effect of a CCS conductor is clearly seen by comparing plots of mfr
> data for CCS cables on the same graph as for cables with a solid copper
> center. CCS line has more loss below 10 MHz than copper.
>
> 73, Jim K9YC
>
> On Sun,2/5/2017 7:24 PM, Wes Stewart wrote:
>> If you follow this link http://k6mhe.com/n7ws/Ladder_Line.pdf to my
> Balanced Transmission Lines in Current Amateur Practice<http://k6mhe.com/n7ws/Ladder_Line.pdf>
> k6mhe.com
> Balanced Transmission Lines in Current Amateur Practice by Wes Stewart, N7WS 28 -Feb -99 Page 2 of 9 Rev 25 Mar 99 structed with a minimum of spacers so the ...
>
>
>> paper and look at Table 1, it gives the measured values of four
>> different Wireman P/Ns.
>>
>> Note that these are 50 MHz values and transmission line Zo and Vp are
>> anything but constant at lower frequencies.  Likewise, these
>> particular lines use copper-clad steel conductors that "misbehave" at
>> lower frequencies so Eq 4 somewhat falls apart when the conductors do
>> not have a well-developed skin effect. I mentioned this in the paper
>> but did not account for it in the equation.
>>
>> Wes  N7WS
>>
>>   On 2/5/2017 5:11 PM, Hardy Landskov wrote:
>>> Hi Jim and all,
>>> The email below reminds me of a problem I had some years ago with
>>> "450 ohm
>>> window line". Nothing seemed to work. I then found an article that
>>> explained
>>> how to measure the Zo of coax/ladder line. I measured a piece of
>>> window line
>>> and it was 374 ohms! I found out in the archives that W8JI had
>>> measured 377
>>> ohms with a piece of window line. We exchanged emails and he was
>>> elated that
>>> I had verified his results.
>>> Here you have two different sets of equipments, two different runs of
>>> ladder
>>> line, and different times. I was very happy myself. I have an HP8753B
>>> so it
>>> was no problem to run through the numbers. It was a very eye opening
>>> exercise!!
>>> Bottom line: Use 375 ohms for matching tuners and other things when
>>> using
>>> this line.
>>> 73 Hardy N7RT/4
>>>
>> _______________________________________________
>>
>>
>>
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