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hi,

SV4401A is a product of SYSJOINT, please visit for more details

hi,

Is the coaxial trap a two-port device? If so, connect the VNA ports to the trap ports and observe the logmag trace, just like testing a filter.

I feed the RFfrom a signal generator through a resistor, then read the
voltage across the trap as it is tuned. The resistor value depends on your
test equipment. If you have a 50 ohm source, start with maybe 450 ohms to
give a ten to one ratio. The voltage drops as you approach the resonant
frequency. I've used this method for almost 50 years to identify the SRF
frequency of inductors, as well.
You can also use this method to pre tune an RF circuit before powering it
up. It puts you close to the ideal settings. I'm a retired Broadcast
Engineer.

Hello all. Is there any documentation someone can point me to that details how to test coaxial traps (I am building ones for 40m & 80m) using a NanoVNA?

No mention of who builds it, who does the firmware, software that it
is compatible with ...

Hi
I don't know,
I. Got my one from banggood and it arrived in the UK in 10 days,
And a great price,
Dave

YZTERA SV4401a 7 inch Touch LCD 50khz 4.4ghz Vector Network Analyzer
Found on Amazon.

I was able to ship a completed Norcal 40a board complete with potentiometers and connectors to Turkey for $11.40 cad using Canada Post surface mail. The package weighed in at 225 grams.
Totally untracked however. Hopefully it arrives soon.

I've had relatively few problems with my Aliexpress purchases, and Aliexpress has always found in my favour for those occurrences with a refund. It's a PITA to navigate their complaints system...

73 de Russ, va3rr

My experience with having small orders shipped from the US to Chile by mail, since about 1980 until nowadays, is like this:

In the beginning, there was airmail and surface mail. Airmail arrived quickly but the cost was too high with heavy items. Small items mailed at letter rate in an envelope, about $1, while items up to about 2 pounds mailed as parcel post for about $7. Surface mail was very inexpensive, like $10 for a big box full of heavy stuff, but took 3 months to arrive and often smelled of fish and algae.

Later, like the 1990s, there were three options: "First class mail", which was really last class, "Priority mail", and "Express mail". Shipping small items as letters was no longer legal, but some sellers did it anyway. First class mail sometimes didn't arrive, as it was nonlisted and nontrackable. Priority mail was the way to go: It arrived quickly, it could be registered, and a typical small box full of parts, large enough to put in a NanoVNA with its own box, cost about $14 to ship. Express mail was more expensive, registered by default, but wasn't any faster than Priority mail. In Chile all three systems were handled the same. And all came by air. The only difference was the handling in the US, and the priority level to get on a plane. When planes were chronically full, typically before Christmas time, "First class mail" parcels apparently were left to rot, or taken home by the someone.

The later developments were basically drastic price increases, ever more restrictions on what can be shipped, also on size and weight, and an increasing unwillingness of US companies to ship by mail at all, trying to force customers instead to make do with super-expensive Express companies, that deliver in 3 days, but only ever to street addresses in cities. All those of us who live in the countryside cannot get anything through any Express company! The postal service instead holds the parcels at the nearest post office, for pickup by us rural hillbillies.

Shipping from China, when it started, was usually by China Post, Hongkong Post, apparently some sellers also had access to Chinese offices of foreign postal services like Singapore Post and even Deutsche Post. Typical charges for airmail with full tracking was, and still is, about $4 for small items. The parcels arrived quicker than from the US. The weirdest thing I ordered from China that way was a hedge cutter attachment for my weed whacker, a nasty-looking thing full of sharp teeth. The Chinese seller just wrapped it in two layers of bubble plastic and put it in the mail. It arrived just fine, with most of the bubble wrap gone. Shipping charge was $6 or so. A company in the US wanted to charge me $400 for FedEx shipping.

But then the craze of company-run logistics began. First Amazon, then companies like AliExpress and eBay, started to set up their own shipping networks. At first they allowed buyers to choose between those and the postal service, but later they started forcing every customer to use the company-owned shipping system, or a super-expensive Express service. For years AliExpress happened to use the Chilean postal service for last-mile distribution, so that was OK with me, and I made many purchases that way. But recently they moved from postal distribution to an unknown little local shipping company, and that was the end! That company does not deliver to my entire area, not even to the town where I do my shopping, and AliExpress blamed me for that, and I lost my money.

So now I'm down to trying to find individual companies in China and elsewhere, or some few eBay sellers in countries where eBay still offers a choice of shipping that includes the postal service, when I need something that's not available locally. The high postal rates currently make the US the least attractive country in the world to order from, at least for me here in the Chilean backcountry. I have gotten parcels from the UK, Australia, South Africa, Thailand, Germany, Sweden, by air mail, not as cheap as from China but far less expensive than US postal rates.

With COVID-19 everything went crazy, it became virtually impossible to get anything from anywhere by mail, but then China was the first to get back to normal.

You may want to check the cable-to-plug interface of the supplied coax cables.

On mine the ground sleves are not soldered or crimped but just hold in place by the shrink tubing. Depending on how I bend or twist the cables I get all sort of funny results.

Fran?ois: I really don't understand why you have such accentuated noise and deviation from
0dB on your post-calibration S21 plot. Mine shows less than .01dB deviation from 1 to 100
MHz. See the attached plot with the vertical axis zoomed in to +/- 0.5dB.

Hello
Indeed the curve you show (nanovna-h4_S21zoom_in.png) is perfect. I have never managed to do better than what I offered you. I don't know the cause. My box is a nanoVNA-F as attached. It has an aluminum alloy case.



I do with :(

73
--
Fran?ois

-----Message d'origine-----
De : Stan Dye
Envoyé : samedi 2 septembre 2023 02:10

That is curious. For your reference, I just did an SOLT cal, and left the cable connected from the last through cal step, and get 0dB as expected across the whole trace.
I set my frequency span from 1-100MHz to match the range Fran?ois showed in his graph.
Here is a screen capture. Note that the trace is on the second line down on the display by default, since that is the default 0dB reference for the S21 trace. Are you perhaps misinterpreting that as being -3dB? Each trace can have its own scale and 0 reference position - so verify that you have that set correctly. The current scale/div is the number just after the label for each trace at the top of the screen, followed by a / and the current value at the active marker.

Fran?ois: I really don't understand why you have such accentuated noise and deviation from 0dB on your post-calibration S21 plot. Mine shows less than .01dB deviation from 1 to 100 MHz. See the attached plot with the vertical axis zoomed in to +/- 0.5dB.
Stan

Hi Stan,
Yes, I am sure that the cables I am using are the same as the ones used to calibrate the VNA. I actually left everything connected after doing the T calibration and then did my measurements. The only parts connected are the two coax cables and the F-F SMA adapter. The info at the top of the screen show S21 Logmag. I also did a Reset before calibrating.

Fran?ois, by "over the entire plot" I mean the entire trace. It is a flat line at about -3dB.

On 9/1/23 11:38 AM, G4OJW wrote:

I see Thailand as Group 6 and $72.01 for 4lbs under one of the many confusion options, but the $225.02 is nowhere to be found. Anyway they should offer a simply airmail option there are so many options, not only express, if they want people overseas to buy from them in larger numbers.

Group 6 for the first column (Global Express Guaranteed). You need to look all the way over to the right for the FCPIS Price Group (under First Class Mail Package International Service)

There it's group 10. Group 6 for First class International Mail.

On 9/1/23 10:48 AM, Dave Merrill wrote:

Unless the rules have changed, international letters may only contain
documents or printed material. Everything else has to go at package rates.
Dave N9ZC
On Fri, Sep 1, 2023, 11:28 AM Jim Lux <jimlux@...> wrote:

USPS First Class International Package is for less than 4lb is about $20
to many overseas destinations. (I can't download the rate chart now for
some reason).




For some small stuff, you can send it as a letter for somewhat less (not
pennies, more like $10).

Finally got the file...It's attached.

Since someone used the example of Thailand earlier, that's Group 10 (for packages), the UK is group 20

For a 8 ounce package - $17.40 for group 10, $18.90 for group 20 ( Ihave no idea why Thailand is cheaper than the UK... International postal rates have little to do with actual cost, maybe it's deferred compensation for tea shipments pitched into the harbor)


There is a huge breakpoint at 8 ounces, BTW, for group 10 it nearly doubles

groups are here:



For what it's worth, my TinySA, in its box, is 7.7 ounces. So moving to any of the 4" units probably would push you into the 12-36 ounce bracket.

Unless the rules have changed, international letters may only contain
documents or printed material. Everything else has to go at package rates.

Dave N9ZC

USPS First Class International Package is for less than 4lb is about $20 to many overseas destinations. (I can't download the rate chart now for some reason).




For some small stuff, you can send it as a letter for somewhat less (not pennies, more like $10).

Hello

You should tell us what you call "over the entire plot".

Attached are the results of my measurements on my NanoVNA-F between 1 MHz and 100 MHz with nanovna-saver. The measurement is made on the original cords each equipped with an SMA - BNC♀ adapter. The connection is made with a BNC connector♂/♂. Calibration is done on the BNC plugs♀ with an N HP 908A load and an N♂ short circuit


73
--
F1AMM
Fran?ois

Some ideas to consider:
Do you have the ports hooked together in the exact same way they were
during the thru part of the calibration procedure?
I suspect not, because that last thru step of the calibration sets the 0dB
point of the thru signal, and the way to verify that the calibration took
proper effect is to hook the ports together and observe the constant 0dB
S21 logmag trace.
So maybe you are making a mistake in the cal procedure. Or does the cable
you are connecting with now have a T connector to some other monitoring
point? Splitting the signal would cause a 3dB loss. Another thing to
check is if you are really looking at S21 logmag, i.e. is the trace really
set to what you think it is. The display labels should confirm that.

Your computer was compromised, nothing to do with Ebay or Paypal.

On Fri, 1 Sept 2023 at 01:25, Julio VE3FH via groups.io
<ve3fh@...> wrote:

No, I totally disagree with your statement. Based on personal experience, every time I had a credit card compromised it was shortly after either some eBay order or some PayPal payment processing. Last year when I called the bank to report a fraudulent transaction the first thing they asked me was if I had used the card on PayPal adding that several customers reported similar transactions that day with the commonality being PayPal.
I actually I have a second credit card that I use to pay for gas, groceries, etc. and never use online, guess what? that one never got hacked.
I agree with you though that there's no such thing as free shipping, the reality is that S&H is included in the price but no merchant is going to advertise that way, that's just a marketing tactic.
73,Julio VE3FH

On Wednesday, August 30, 2023 at 06:05:16 p.m. EDT, Dragan Milivojevic <d.milivojevic@...> wrote:

You have a million times greater chance of your card details getting
stolen when paying for gas than
the same happening when using PayPal.

On Wed, 30 Aug 2023 at 23:00, Julio VE3FH via i
<ve3fh@...> wrote:

I share your concerns. I bought my TinySA from the SeeSii store in ebay.ca, it and arrived in six days and shipping was USD $2.99, they do carry the NanoVNA H4 and I'll probably buy a NanoVNA from them shortly. The issue with ebay is that payments are processed by paypal so you risk your credit card being compromised, it happened to me at least three times already.
73,Julio VE3FH