Re: Anyone had news from Maggie King?
I placed an order a couple of weeks back for the H4. Just got a shipping notification from alibaba.
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Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
Hi to W1RS,
I don't know you very well but
I hope you understand my post was mostly jest. I figured any one with a
"W" call sign would understand.
Nice meeting you,
I hope to talk more about non-50 ohm measurements.
I have a lot of 300 - 450 ohm ladder line work to do. And I am just
starting out with a VNA. So I will be asking for help.
I also want to take a closer look at the "some what popular" wide band low
Z to high Z -"half wave"- end fed toroid transformer and see if there is
room for improvement. I have used a bob-tailcurtain on 80meters in the past
and had amazing results. I have also used the half of a bob-tail and I
recommend it. Some People have no idea what can be done on 80m day after
day with less than 100 watts right thru a sunspot minimum. Those are my
ambitions, more later. I am just starting out with using a VNA an still
have lots of reading to do.
Nels Nelsen
NE7LS
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On Tue, Feb 18, 2020, 6:53 AM W1RS <Deflatermaus@...> wrote: Nels, I should have said Hi-Z broadband transmission lines. Of course the
tube amp situation is as Dave stated. I went to
to calculate the spacing
for the ladder line.
I was amazed at how rapidly it increases with the impedance. The
line-to-line capacitance requirements just get really small. According to
the equations presented,
300 Ohms --> 0.3 "
450 Ohms --> 1"
700 Ohms --> 8.5 "
1000 Ohms --> 105"
I'm very impressed with the nanoVNA, but with the 50 Ohm bridge design, I
would not expect to achieve good accuracy at measuring at greater than 10
times the bridge Z, especially at higher frequencies.
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Re: Anyone had news from Maggie King?
I ordered from Maggie in Mid January, and just recieved a note from one of her co-workers yesterday that shipment was arranged and that they would have a tracking number for me soon. I had received a note from Maggie in Early Feb that they were shut down for Chinese new year, and another note a few days later that they would resume shipping on Feb 21 due to the virus outbreak.
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Re: SWR trace always showing 1:1 as flat line at bottom of screen
You may need to use a smaller freq sweep range and select only the bands you want to sweep individually. The device only has 100 data points of resolution and a full 30Mhz sweep could easily miss the SWR dips with only 100 data points.
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If the bonding of the connector grounds changes the measurement, then the ground circuitry external to the VNA is part of what is being measured. This is not good. There is no way to separate the measurement of the ground path from that of the DUT, and every setup will give different answers. One solution is to put the VNA board sandwich into as much of a box as the display allows and solidly bond the connector grounds to the box. This has worked fine for me.
So, the question is, has anyone actually done a measurements of some parameter (S21 isolation maybe?) that shows the badness of connector bonding? We need numbers!
Bob W7PUA
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A Good source for Calibrated Loads in formats other than SMA -
#calibration
Array Solutions sells precision calibration loads in formats other than SMA if you don't want to make your own -
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On Mon, Feb 17, 2020 at 08:39 PM, David Eckhardt wrote: I believe there is a place in Saver for a multiplier or
arithmetic. Can you tell me where it is exactly? I can't find it. I tried changing the 50 ohms to 300 ohms in the Saver calibration standards and doing the calibration in the program with 300 ohm load, but despite showing the impedance correctly, it still shows the SWR wrong, as if it was for 50 ohms. It only shows the SWR correctly when I calibrate with a 300 ohm load with the standard set to 50 ohms in program, but then it shows the impedance wrong.
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Re: Anyone had news from Maggie King?
Apple can't get iPhones...? Foxconn is using studentson a skeleton crewed assy. line.?
I'm waiting for a nanovna too.
JimMc
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On Tuesday, February 18, 2020, 5:31:44 AM PST, Pierre Martel <petem001@...> wrote:
I ordered a Nanovna H4 from alibaba begenning of the month, she told me it would ship before the 15, but did not had any news since.
Am I the only one?
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Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
Robert, please take a look at my 9.8k Ohm measurements. With the S21 method, the results are acceptable. /g/nanovna-users/message/11027For a lower resistor, results are much better (S21 method): [image: image.png] Using an external bridge with a reference higher than 50 OHm would improve measurements, but some difficult calculations are needed. /g/nanovna-users/topic/64426024#8601Ady YO2NAA
On Tue, Feb 18, 2020 at 4:53 PM W1RS <Deflatermaus@...> wrote: Nels, I should have said Hi-Z broadband transmission lines. Of course the
tube amp situation is as Dave stated. I went to
to calculate the spacing
for the ladder line.
I was amazed at how rapidly it increases with the impedance. The
line-to-line capacitance requirements just get really small. According to
the equations presented,
300 Ohms --> 0.3 "
450 Ohms --> 1"
700 Ohms --> 8.5 "
1000 Ohms --> 105"
I'm very impressed with the nanoVNA, but with the 50 Ohm bridge design, I
would not expect to achieve good accuracy at measuring at greater than 10
times the bridge Z, especially at higher frequencies.
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High Z measurements with the NanoVNA
Hi all
I have some time wanted to give my detail view on how to avoid the measurement error discussed and demonstrated in this forum.
I have used resistor measurements as the example but it is of general interest for many other measurements of components
I hope it can be of inspiration
It is attached but a link is also provided (probably killed by the io group system ?)
The link is measurements with a VNA.pdf <>
Kind regards
Kurt
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Re: SWR trace always showing 1:1 as flat line at bottom of screen
I noticed that sometimes after doing a cal without a reset there where sometimes inconsistencies after I verified that each Smith chart indication was in the correct position for each of the SOL cal caps, so I had to do it over. But even so the SWR trace remained flat-lined.
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Re: Anyone had news from Maggie King?
Mine was shipped apparently on 17Jan2020 to Mauritius. I hope to see it soon!
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On 18 Feb 2020, at 19:50, nanovnagroup@... wrote:
On Tue, Feb 18, 2020 at 05:31 AM, Pierre Martel wrote:
I ordered a Nanovna H4 from alibaba begenning of the month, she told me it
would ship before the 15, but did not had any news since.
Am I the only one? I got a message from her on 2/13 that they where finally resuming shipments, after the recent holidays and the CVE outbreak.
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Re: Simultaneous S11 and S21 measurements ?
Neal,
With the nanovna-saver software you can display up to 6 sweeps with combinations of 6ea S21 and 16ea S11 and 1 combo S11/S21 options.
Don't know about the unit itself options.
--
Chuck, W5USJ
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Re: Anyone had news from Maggie King?
On Tue, Feb 18, 2020 at 05:31 AM, Pierre Martel wrote: I ordered a Nanovna H4 from alibaba begenning of the month, she told me it
would ship before the 15, but did not had any news since.
Am I the only one? I got a message from her on 2/13 that they where finally resuming shipments, after the recent holidays and the CVE outbreak.
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Just a thought regarding SMA connectors. When I worked on NASA projects,
the mandate was 20 connects and disconnects and the connector(s) was
removed and discarded. They are excellent connectors from an RF
standpoint, but certainly not as rugged as those larger connectors we are
used to.
Dave - W?LEV
Dave - W?LEV
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On Tue, Feb 18, 2020 at 1:41 AM <nanovnauser@...> wrote: well looking at the link to owen duffys solution it looks like the ground
is common to both connectors then?,cheers all 73
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
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Re: SWR trace always showing 1:1 as flat line at bottom of screen
I've had that a few times too. I've never been able to figure out why but recalibration seems to always get it going again. Not much help other than I've had that too. I only need the 3 calibration steps but I want to say I've noticed it at least once when I don't complete all the calibration steps. Not everytime though.
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Re: Anyone had news from Maggie King?
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Re: Anyone had news from Maggie King?
Courier services in China are resuming, you can contact Maggie at sales11@...
hugen
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Re: HI-Z EVALUATUTION - MEASURED DATA COMPARISON with HP 8753C
Nels, I should have said Hi-Z broadband transmission lines. Of course the tube amp situation is as Dave stated. I went to to calculate the spacing for the ladder line.
I was amazed at how rapidly it increases with the impedance. The line-to-line capacitance requirements just get really small. According to the equations presented,
300 Ohms --> 0.3 "
450 Ohms --> 1"
700 Ohms --> 8.5 "
1000 Ohms --> 105"
I'm very impressed with the nanoVNA, but with the 50 Ohm bridge design, I would not expect to achieve good accuracy at measuring at greater than 10 times the bridge Z, especially at higher frequencies.
|
Anyone had news from Maggie King?
I ordered a Nanovna H4 from alibaba begenning of the month, she told me it would ship before the 15, but did not had any news since.
Am I the only one?
|
Chris Prosser
goscickiw
Kurt Poulsen
Chuck Carpenter