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On Thu, Oct 1, 2020 at 11:01 AM, Danny K5CG wrote:

The SARK-110 is an antenna analyzer. I know it's a tiny point of distinction,
but one nonetheless.

The Sark-110 is marketed as an Antenna Analyzer but it is a one port (s11 only) VNA. The RigExpert Analyzers are one port VNA's as well.

Roger

And still SMA connectors.

Those who do not learn history are doomed to repeat it.

There was an application note written for the SARK-110 VNA on measuring traps. <

The SARK-110 is an antenna analyzer. I know it's a tiny point of distinction, but one nonetheless.

Unfortunately I cannot reproduce the problem, I set the range 450-490, 460-475. Calibrated, everything went smoothly.

I later added a reset of the generator cache when starting the scan, maybe this will help.

Alan,
Why not trying to increase the span by 10mhz at a time to see where you get correct readings? That may help to narrow down the issue.?


On Thu, 1 Oct 2020 at 10:10 AM, Alan “W2AEW” Wolke<alan.wolke@...> wrote: Hello DiSlord,

Thank you for the reply.? I tried this procedure, and still have the same problem.? I am not sure why.
When I run through the calibration procedure over a wider span, it works perfectly as expected.
For some reason, only when I repeat the exact same procedure over this narrow span (460-475MHz), I have the problem.
I have tried your process of just doing ISOLN and THRU and saving, with the same result.
(this is on a -H4, hardware version 4.2.1)

I also have your 1.0.39 firmware on my new SAA-2N, and it works perfectly under the same conditions.

Do you have any other suggestions?

Thank you,
Alan

Hello DiSlord,

Thank you for the reply. I tried this procedure, and still have the same problem. I am not sure why.
When I run through the calibration procedure over a wider span, it works perfectly as expected.
For some reason, only when I repeat the exact same procedure over this narrow span (460-475MHz), I have the problem.
I have tried your process of just doing ISOLN and THRU and saving, with the same result.
(this is on a -H4, hardware version 4.2.1)

I also have your 1.0.39 firmware on my new SAA-2N, and it works perfectly under the same conditions.

Do you have any other suggestions?

Thank you,
Alan

This is calibration issue.

Reset device (off/on), load your calibration slot, and not made calibration reset, do only ISOLN/THRU after press done and save to slot.

PS Firmware allow made apart calibration OPEN/SHORT/LOAD and ISOLN/THRU (if not reset before).

Does S21 look "normal" in uncalibrated state?

Perhaps an open cable or a failed connection during calibration?

I just tried the previous version - same result - S21 very noisy, sitting well above 0dBm with both ports open. Strange.

Same version. Judging by the git logs, DiSlord regularly merges changes from
H into H4 so the basic functionality should be the same.

On Thu, 1 Oct 2020 at 02:51, Jerry Gaffke via groups.io <jgaffke=
[email protected]> wrote:

Same firmware?
I believe the 2.8" unit has a 2.8" nanovna-H has an stm32f072cbt6 with
16kbytes of RAM
vs an stm32f303cct6 on the nanovna-H4 with 40kbytes of RAM.

And that for this reason the 2.8" cannot support 401 data points in
standalone mode.

Jerry, KE7ER


On Wed, Sep 30, 2020 at 03:09 PM, Dragan Milivojevic wrote:

Used your settings on a 2.8" unit, same firmware.
Everything works as expected.
Did you try to reset the calibration?

On Wed, 30 Sep 2020 at 23:51, Alan “W2AEW” Wolke <alan.wolke@...>
wrote:

I updated my -H4 with Dislord's latest v1.0.39 firmware, and for the

most

part it looks great - up to 401 points, adjustable measurement BW, etc.
All good. However, I have a strange problem with it under certain
conditions:

I was setting up to measure a VHF duplexer S21 as a test. I set Start
frequency to 460MHz, Stop frequency to 475MHz, just one trace enabled

to

show S21, using 1kHz BW and 401 points. After setting the stimulus and
trace/channel, I run though the calibration process and save it. But,

once

I did that, the S21 trace was above 0dB when the connectors were left
open! I expected it to be -80dB or better, but got this strange

result. I

reverted back to my original firmware (Hugen's v0.0.5), and the problem
isn't there.

Am I setting something wrong, or did I uncover a bug?

Same firmware?
I believe the 2.8" unit has a 2.8" nanovna-H has an stm32f072cbt6 with 16kbytes of RAM
vs an stm32f303cct6 on the nanovna-H4 with 40kbytes of RAM.

And that for this reason the 2.8" cannot support 401 data points in standalone mode.

Jerry, KE7ER

That is strange. Try the previous version (
)


On Thu, 1 Oct 2020 at 01:30, Alan “W2AEW” Wolke <alan.wolke@...>
wrote:

I did, several times. Reset and re-ran calibration over this narrow range,
some result. If I use a cal over a much wider span, and rely on cal
interpolation, it works. Just not if I cal over this 15MHz span. Strange.

I did, several times. Reset and re-ran calibration over this narrow range, some result. If I use a cal over a much wider span, and rely on cal interpolation, it works. Just not if I cal over this 15MHz span. Strange.

Used your settings on a 2.8" unit, same firmware.
Everything works as expected.
Did you try to reset the calibration?


On Wed, 30 Sep 2020 at 23:51, Alan “W2AEW” Wolke <alan.wolke@...>
wrote:

I updated my -H4 with Dislord's latest v1.0.39 firmware, and for the most
part it looks great - up to 401 points, adjustable measurement BW, etc.
All good. However, I have a strange problem with it under certain
conditions:

I was setting up to measure a VHF duplexer S21 as a test. I set Start
frequency to 460MHz, Stop frequency to 475MHz, just one trace enabled to
show S21, using 1kHz BW and 401 points. After setting the stimulus and
trace/channel, I run though the calibration process and save it. But, once
I did that, the S21 trace was above 0dB when the connectors were left
open! I expected it to be -80dB or better, but got this strange result. I
reverted back to my original firmware (Hugen's v0.0.5), and the problem
isn't there.

Am I setting something wrong, or did I uncover a bug?

I updated my -H4 with Dislord's latest v1.0.39 firmware, and for the most part it looks great - up to 401 points, adjustable measurement BW, etc. All good. However, I have a strange problem with it under certain conditions:

I was setting up to measure a VHF duplexer S21 as a test. I set Start frequency to 460MHz, Stop frequency to 475MHz, just one trace enabled to show S21, using 1kHz BW and 401 points. After setting the stimulus and trace/channel, I run though the calibration process and save it. But, once I did that, the S21 trace was above 0dB when the connectors were left open! I expected it to be -80dB or better, but got this strange result. I reverted back to my original firmware (Hugen's v0.0.5), and the problem isn't there.

Am I setting something wrong, or did I uncover a bug?

You find hints in the manual in the Wiki. The RED led ( i think ), has the behavior of a USB power pack LED, because there is a power-pack chip (IP5303) in the Nano to charge the battery and a "watch dog timer" to take off the Nano if there is no activity after 30 sec after power off. The BLUE LED gives some activity of the processor chip.

Let me clarify that scattering parameters expressed as return loss S11, imply a power measurement.

Ken

The formulas were taken from G3TXQ spreadsheet so compare with it?
If you are good with excel/libreoffice graphs you can mark the regions
where Z > 2K and R > |X| (the desired resistive choke) same as G3TXQ
did in his graphs.

BTW read up on stacked cores on G3TXQ site (if it is down use archive.org,
it gets hacked on a regular basis). Usually it is better to use them in
series.

Well, at last I've loaded my .s2p into excel and generate a graphic of my choke..
I would like to know how reliable is the whole thing.....

Federico
ik3umt