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RF Demo Kit Testing tutorial released


BH5HNU
 

Hi everyone, we(NanoVNA-F team) just released the RF Demo Kit Testing tutorial.
In general, it may not be detailed enough, but it should be helpful for users(in this nanovna-users group) who purchase the gadgets :-)
Please note this, two steps must be performed before testing:
Step 1. Connect the two 20CM SMA to IPEX adapter cables to the NanoVNA-F machine.
Step 2. Recalibrate the machine using the 13 Short, 14 Open, 15 Load, and 16 Thru circuits on the test board, and save the parameters in 0.
And there's one more thing, :-)
Fans please look for the new version to purchase, with WWW.DEEPELEC.COM website information, the old version WWW.SxxxxxxT.COM has been discontinued.
Full tutorial at: http://deepelec.com/rf-demo-kit/

By the way, if the moderator thinks that the post is suspected of advertising, please handle it with full authority. :-)


El Sid
 

What’s the difference between the Deepelec and the many s*******t boards offered at AliExpress, besides the higher price?


BH5HNU
 

Hi,
Starting from the end of November 2019, we(NanoVNA-F team) no longer produce RF Demo Kits with WWW.S******T.COM mark.

On Fri, Dec 6, 2019 at 05:06 AM, El Sid wrote:


What’s the difference between the Deepelec and the many s*******t boards
offered at AliExpress, besides the higher price?


Rudi
 

The RF Demo Kit NWDZ Rev-01-10 is available via Ebay for about 15 EUR.
A documentation can be found at: http://deepelec.com/rf-demo-kit . I will just extend it a bit about details and *practical* *usage*.

For more *details* see the *wiki* *page*: https://groups.io/g/nanovna-users/wiki/RF-Demo-Kit-use

The micro coax plug is named U.FL/IPX, 50 Ohm, about 2mm diameter. For more details see on https://en.wikipedia.org/wiki/Hirose_U.FL.

/!\ Excerpt: "Female U.FL connectors are not designed with reconnection in mind, and they are only rated for a few reconnects (approximately 30 mating cycles [5]) before replacement is needed. The female U.FL connectors are generally not sold separately, but rather as part of a pigtail with a high-quality 1.32 mm doubly shielded cable, which allows for a low-loss connection."

/!\ The cable crimp in the little U.FL connector in not very solid. In order to avoid a cable and plug separation you should solder the coax cable shield crimp, see the picture on the right.

I made once this experience, and it was very difficult to repair the cable connection. In order to fit the center wire, you need to solder it with very little tin, and open the socket a little with a needle. And you need some patience, good light and a good magnifier glass.

/!\ To make a connection with the U.FL coax plug, just use your finger, no tool. Use a little flat screw driver to lift off the U.FL female plug.

73, Rudi DL5FA


Klaus Wörner
 

I bought this kit, too. I wondered about the very bad measurements in the inductive part. So I got it to the QRL, where we have a HF-Labor. The results with the Rhode&Schwarz are shattering. I'ts not recommended to buy it.


Rudi
 

Hello Klaus,
Could you please tell more details:
1. which Test field do you mean?
2. Do you have a screen shot of a diagram?

I have tested Testfield 1 Low Pass Filter 30 MHz, please see at:
https://groups.io/g/nanovna-users/wiki/RF-Demo-Kit-use
or
Test field 12 Notch filter at about 500 MHz:
RF-Demo-Kit_12-BSF-500MHz_Saver.png

I have not seen any problems.

73, Rudi DL5FA


 

On Wed, 8 Jan 2020 at 10:14, <reuterr@web.de> wrote:

Hello Klaus,
Could you please tell more details:
1. which Test field do you mean?
2. Do you have a screen shot of a diagram?

I have tested Testfield 1 Low Pass Filter 30 MHz, please see at:
https://groups.io/g/nanovna-users/wiki/RF-Demo-Kit-use
or
Test field 12 Notch filter at about 500 MHz:
RF-Demo-Kit_12-BSF-500MHz_Saver.png

I have not seen any problems.

73, Rudi DL5FA
Rudi,
The problem is the connector used on that is totally unsuitable. It is not
designed for repeated connections. Even the original manufacturer of the
device, Hirosose, rate it at 20 connections/disconnections. Hirose doesn't
release the diagram of the connector, so every cheap connector is going to
be some variation on that.

I almost choked with laughter when I read the word “knockoffs” being
mentioned by the maker of that board. It just seemed strange to think
anyone would knock off a design that’s so obviously flawed, and so easy to
improve (change connectors to SMA).

You should use a special tool for removing them. This one is made by
Hirose, who designed the U.FL connector.

https://uk.farnell.com/hirose-hrs/u-fl-lp-n2/extraction-jig-u-fl-series/dp/1688076?st=ufl%20connector

So the design is so fundamentally flawed it is beyond belief. Anyone that
buys one can expect problems.

Dave


 

On Tue, 7 Jan 2020 at 15:04, <reuterr@web.de> wrote:

The RF Demo Kit NWDZ Rev-01-10 is available via Ebay for about 15 EUR.
If you buy one and it fails, I would report via eBay as poor quality. You
will soon get your money back.

Dave


Rudi
 

On Wed, Jan 8, 2020 at 01:09 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:
Rudi,
The problem is the connector used on that is totally unsuitable. It is not
designed for repeated connections. Even the original manufacturer of the
device, Hirosose, rate it at 20 connections/disconnections. Hirose doesn't
release the diagram of the connector, so every cheap connector is going to
be some variation on that.

I almost choked with laughter when I read the word “knockoffs” being
mentioned by the maker of that board. It just seemed strange to think
anyone would knock off a design that’s so obviously flawed, and so easy to
improve (change connectors to SMA).

You should use a special tool for removing them. This one is made by
Hirose, who designed the U.FL connector.

https://uk.farnell.com/hirose-hrs/u-fl-lp-n2/extraction-jig-u-fl-series/dp/1688076?st=ufl%20connector

So the design is so fundamentally flawed it is beyond belief. Anyone that
buys one can expect problems.
Dave
Hello Dave,

Thank you very much for the hint with the *extraction tool* for the U.FL connector.
Unfortunately it is *more expensive* than the *RF Demo Kit*.
I am using a 1.0 mm wide flat screw driver for extracting.
Up to now it works fine, if you press the cable down with your finger,
while you are levering with the screwdriver.

I agree, if you handle the U.FL connector *careless*, you will have sooner or later a *problem*.

By the way the data sheet from Hirose tells about *Durability* the number *30* not 20 cycles.
Compared with normal open milk, which is sour for sure after about a week, if not cooled,
the number of plugging cycles for an U.FL plug is a *minimum of 30*,
with a *good probability of more*, if you handle it *careful*.

For me it is a *learning tool*.
There are 25 connectors on the board, on 18 Test fields.
So, if you test and document each Test field once, including calibration,
you are still under the number of 30 cycles.
Beside that, you have *2 cables*.

Why do you score off a useful cheap learning tool, without trying that yourself?

Have you had a look to my "RF Demo Kit" description at:
https://groups.io/g/nanovna-users/wiki/RF-Demo-Kit-use

73, Rudi DL5FA


n5kzw
 

That tool looks like it would take all of 5 minutes to make. - Ed


 

On Wed, 8 Jan 2020 at 21:45, n5kzw <n5kzw@arrl.net> wrote:

That tool looks like it would take all of 5 minutes to make. - Ed
Yes, but it does not solve the problem that a completely inappropriate
connector is used.


Rudi
 

Hello Dave,

I agree to your statement, if the RF Test Kit is used for an university course.

73, Rudi DL5FA


 

On Wed, 8 Jan 2020 at 22:32, <reuterr@web.de> wrote:

Hello Dave,

I agree to your statement, if the RF Test Kit is used for an university
course.

73, Rudi DL5FA
I personally don't think they will last long in the hands of a ham trying
to learn, or demonstrate it to others.

I rather suspect that sooner or later someone will produce something
similar with SMA connectors, and then nobody in their right mind would buy
a U.FL connector version.

Dave


Leif M
 

There are several SMA board edge connectors on Ebay. There are models for 1.6mm and 1mm thicknessess. And of course normal models for soldering into board.


Klaus Wörner
 

I've screenshotted the Number 8 and 10 of the new version (serial LC and L):
The capacitive parts at the bottom are good, but the top side isn't it. The measurement with the professional equipment are similar.


Rudi
 

On Thu, Jan 9, 2020 at 09:50 AM, Klaus Wörner wrote:

I've screenshotted the Number 8 and 10 of the new version (serial LC and L):
The capacitive parts at the bottom are good, but the top side isn't it. The
measurement with the professional equipment are similar.
Hello Klaus,

Thank you very much for providing the screen shots.
I have made two measurements with *Test field 8*.

1. In Test field 8 the inductor looks like to have nominal 470 nH.
If you accept a tolerance of +/- 10 % = 423 - 517 nH,
the usable frequency range is measured to 3.4 - 126 MHz.
Above 394 MHz the inductor becomes capacitive.
See nanoVNA-Saver diagram: RF-Demo-Kit_8-470nH_Saver.png

2. A comparable measurement with the semi-professional FA-VA5 and VNWA software.
If you accept a tolerance of +/- 10 % = 423 - 517 nH,
the usable frequency range is measured to 1 - 128 MHz.
Above 375 MHz the inductor becomes capacitive.
See VNWA diagram: RF-Demo-Kit_8-470nH_VNWA-VA5.png

In my understanding both diagrams show *comparable results*.

Comparing with your screen shot of *Test field 8* I assume,
that you did not made a *Calibration* with the RF Demo Kit *Test fields 13-15*.

73, Rudi DL5FA


Klaus Wörner
 

On Thu, Jan 9, 2020 at 11:18 AM, <reuterr@web.de> wrote:

Comparing with your screen shot of *Test field 8* I assume,
that you did not made a *Calibration* with the RF Demo Kit *Test fields
13-15*.
Hello Rudi,

I have made it. I can redo the measurement with the FA5, but as I told you, we tested it with the Rohode&Schwarz with calibrating and the results are comarable.


Klaus Wörner
 

I've measured with the VA5.
The measurements are the same.


Rudi
 

On Fri, Jan 10, 2020 at 12:22 PM, Klaus Wörner wrote:

I've measured with the VA5.
The measurements are the same.
Hello Klaus,
Your Smith chart 8.png of test field 8 (470 nH) shows at low frequency an Open.
That can not be correct.

To verify your calibration please test:
My Smith chart in diagram RF-Demo-Kit_15-Load_nanovna.png shows
Test field 15 Load (50 Ohm). That should show just a dot in the center.

Could you reproduce that?
73, Rudi DL5FA


Klaus Wörner
 

Yes. The other ones are OK.