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FWIW, I very recently installed BOG antenna. My feed line is one pair in a CAT6 cable that is 235ft long. My first test was to find out what signal pickup the feed line had.
I put a 100 ohm resistor a at the antenna end. (CAT6 is 100 ohm impedance cable) This resistor was inside of the grounded metal transformer box.
In my haste I just connected the pair to the UHF connector on my radio .It received everything! (Note I used the AM BCB to see if the CAT6 feed line picked up signal)
Ok, so I learned that is just feeding the common mode signal directly to the radio. NOT GOOD!
I had 6 iterations, after reading a LAIRD paper on eliminating CM signal from CAT5 cable.
The link has a drawing of my CM signal eliminator. It works very well, but I'm using CAT6 cable not sure if it will extrapolate.
Just a couple notes to help you understand my drawing. I have an amp and relays in the transformer box at the antenna, so I have a DC input on the CM eliminator.
The middle 1 to 1 transformer has a center tap on each winding, and they are both grounded.


Mikek KF4ITA

I also have a question: is this true TDR (pulse generator + oscilloscope) or something else?

Ok, playing with the TDR function. I follow the main trace that starts high then a ping and the whatever on the other end depending on what's there. But what is the other trace, start at the botton and goes to the middle and across??? Also the bottom scale is Meters. What is the left scale, Power?

It's my understanding that the multi impedance transformer feeding an
end fed antenna does not provide the common mode current rejection, on
the outside shield of the coax,? that a dual core 1:1 guanella choke
does. Such a choke prevents the unbalanced currents from coming back
down the coax to the station on the outside of the shield.? A single
core guanella isn't nearly as effective as a dual core.

Another choke at the station entrance, is also helpful to prevent the
outside of the coax from acting as an antenna to local RFI and noises
into your receiver.
Ray, W4BYG

On 6/21/2020 03:31, david.hostetler@... wrote:

Maybe I am missing something here but why not just connect the 6T:3T transformer to provide the impedance transformation AND the ground isolation? That is, only connect the 6T winding to the local ground and the 3T winding to the coax ground going back to the receiver. It would save the loss of the second 1:1 transformer.

--
They say a smart person learns from their mistakes. A
wise person learns from the mistakes of others.



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Hi David,

Thanks for the interest. The intention is to balance the transformer action and minimize common mode noise via electrostatic coupling. When one leg of the so called balun is grounded, coupling is not equal from primary to secondary. The arrangement presented in the HR paper used an electrostatic shield to isolate the transformer winding. The connection of an unun by forcing it to become a balun by proceeding it with a balun is implemented in ring diode mixers for a similar reason, namely improve mixer balance and improved spurious response. The antenna application is similar although the intent is targeting noise reduction.

The losses in these transformers are pretty small, particularly in light of the Beverage antenna response. In any case, the transformer action is quite excellent. I measured the 6T : 2T alone from 100 kHz-to-20 MHz and it achieved 20 dB return loss at ~ 800 kHz. The xmfr maintains that value to nearly 15 MHz. At lower frequency, clearly 73 material will not provide enough L per turn to achieve sufficient reactance. You see that in the S11 chart plot.

Alan

What the heck do you expect for the money? You guys want ferrary performance from a tricycle. If you so ademand of making "quality measurements" and have the "right connector" then buy a piece of real equipment not something that in essence is a toy in the real engineering world. Moreover, SMA connectors are a standard in the microwave world. Hams and hobbyists do not count...there is a reason they are called amateurs. A real commercial grade, not cheap produced SMA edge mount jack will cost you around $25 a piece. So if you buy cheap junk you get cheap performance. But, here is an idea, how about YOU design a board and use high quality board materials and high quality connectors? Go and try to sell them to your typical cheap hobbyist and see how many you will sell... good luck.

On Sat, Jun 20, 2020 at 02:55 PM, DMR wrote:

Hi DiSlord!
when compiling and downloading your code from this link, if you go in and
select the Q FACTOR menu, NanoVNA is freezing. Can this be fixed? If you load
the dfu file below, then there is no freezing.

Thank!

I recompile, but not get fault
But, see my comment in Edy555 commit for it

Need also set MAX_TRACE_TYPE = 13 in nanovna.h and fix this for correct work command

I not add it to my repo

At this time i add some fixes to git

PS for better search error you can enable my extended Hard Fault handler in

void hard_fault_handler_c(uint32_t *sp) {
#if 1

And then get Hard fault you can see all register and address (PC) on display
Then possible open 'ch.list' file and see there is problem

Maybe I am missing something here but why not just connect the 6T:3T transformer to provide the impedance transformation AND the ground isolation? That is, only connect the 6T winding to the local ground and the 3T winding to the coax ground going back to the receiver. It would save the loss of the second 1:1 transformer.

At the end of the day even SMA would be marginal. If you played around with this board frequently you will even wear out SMA connectors. My view is that anything that is used daily should N connectors.

SMA connectors have become a cheap and nasty method of providing "A connector" That wont be reliable in the long term. We now have makes making RF amplifiers and pre-amps with useless SMA connector that require equally useless adapters to bring into the connector world that most of use. It would be far better for HAM and general purpose use that N connectors be used as a standards regardless of the cost, even a cheap N connector would be far more usable than the rubbish SMA connectors that we typical see on mass produced items. The mating cycle life of all these new types of connectors are bad and even worst for the no name branded units.

I sick and tired of wasting timing making junk measurements because of junk materials, connector and cables. I would learn a lot more and have more confidence in what I am learning and doing if the connectors were decent.

I recently re-looked at the Beverage antenna system. Using EZNEC and a reference to an old HR paper, I decided the 9:1 Balun or UnUn still makes best sense. If I terminate the Beverage in an appropriate series R L network, the input Z is close to 470 ohms. I built a 9:1 xmfr on type 73 - 2 shot gun core material. I follow it with a 1:1 xmfr for isolation. I need to keep the coax ground and the Beverage ground system isolated to minimize noise degradation. The response of the transformers constructed is quite good. The return loss from 1-15 MHz is 20 dB or better and still around 17 dB at slightly beyond band edges. At 7 MHz for 1.5 wave or 175 foot long wire, these xmfr(s) appear spot on. The response plots attached are the cascade of the 9:1 (6T:3T) and 1:1 (4T:4T).

Alan

Hi DiSlord!
when compiling and downloading your code from this link, if you go in and select the Q FACTOR menu, NanoVNA is freezing. Can this be fixed? If you load the dfu file below, then there is no freezing.

Thank!

Hi,
Why not make one of these RF Demo Calibration boards with SMA connections and add a few bucks to the price for the added cost of the SMAs? Then we'd all have a useable testing and calibration tool?

--
-----
Glen Jenkins, WB4KTF, Austin, TX

On Sat, Jun 20, 2020 at 02:09 PM, DiSlord wrote:

format on next page
Display->Format->Smith

Ahh, ok.

Possibly problem in old config, need reset it by run

clearconfig 1234

in console after update

On Sat, Jun 20, 2020 at 01:59 PM, Christos SV1EIA wrote:

Nice DiSlord, but.. where is the smithchart gone ?
Changed with a ..target scheme ?

Don`t understand question. Select format not change. Edy555 add Q Factor format on next page
Display->Format->Smith

That's a good question! I was using it on a fixed antenna, that wasn't
being adjusted. I'll play around with it and see if it follows something
that is being tuned.

73, Zack W9SZ

On Sat, Jun 20, 2020 at 3:00 PM John Dusek <johndusek3@...> wrote:

Hi Zack -

What I am trying to do is tune a magnetic loop antenna and have the
nanoVNA actively track the single lowest
SWR across the range as I tune the loop antenna, that would continuously
show me where the antenna is currently tuned as I adjust it towards the
frequency I want.

Does the Search Left/Search Right function actively keep rescanning for
lowest dips, or is a single scan manually executed each time?

John




-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Zack Widup
Sent: Friday, June 19, 2020 8:31 AM
To: [email protected]
Subject: Re: [nanovna-users] Integration of a nanoVNA unit into an antenna
system as indicator of resonance frequency

I'm not sure exactly what you want, but my NanoVNA H4 can find the minimum
value for SWR or s11, whichever is selected. Choose "Marker" > "Search" >
"Minimum" and then "Search Left" or "Search Right."

I did this with my 4 band (40-20-15-10 meters) vertical antenna. I chose
5.0 to 30.0 MHz as the range. I was impressed. The display matches what my
RigExpert AA-600 displays. The routine I listed above would go right to the
dips. I found that my antenna also has minor dips around 9 and 25 MHz.

73, Zack W9SZ


On Thu, Jun 18, 2020 at 8:37 PM John Dusek <johndusek3@...> wrote:

Following up on this thread 6 months later. Does anyone know if there
has been any firmware development performed on a function to track the
lowest SWR for the nanoVNA?

John - W3JED

<

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Nice DiSlord, but.. where is the smithchart gone ?
Changed with a ..target scheme ?

Hi Zack -

What I am trying to do is tune a magnetic loop antenna and have the nanoVNA actively track the single lowest
SWR across the range as I tune the loop antenna, that would continuously show me where the antenna is currently tuned as I adjust it towards the frequency I want.

Does the Search Left/Search Right function actively keep rescanning for lowest dips, or is a single scan manually executed each time?

John

Today, edy555 released a newer version of the nanovna firmware, in which it modified the following:

Add format Quality Factor
Fix label R+Xj to R+jX
Add bandwidth command
some fixes

You can see beta versions of DiSlord in collection.

--
*** If you are not part of the solution, then you are the problem. ( ) ***

Hi Mark,

what about this one:
.
1000014.11.1dba3346IgYDPz&gps-id=pcDetailBottomMoreOtherSeller&scm=
1007.13338.128125.0&scm_id=1007.13338.128125.0&scm-url=1007.13338.128125.0&
pvid=974fdefd-61d5-43c3-8e97-161cf39f18b7
()
?




Milo?


---------- P?vodní e-mail ----------
Od: Maurizio IZ1MDJ <redifon500@...>
Komu: [email protected]
Datum: 20. 6. 2020 17:13:32
P?edmět: Re: [nanovna-users] U.Fl calibration kit
"On Fri, Jun 19, 2020 at 02:29 PM, MarkZ wrote:

Does anyone know of a reasonably priced U.Fl calibration kit?

Thanks,
Mark

Hi , just to learning , why not use the short open load and thru already
available on the board ?
73 de IZ1MDJ Maurizio



"