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Mike,

You need to think about what you are seeing in the time domain.? What the software produces is the impulse response (the positive going blips) and the step response (the steps in your plot) of the network attached.? The steps are the result of multiple trips of a wave traveling through your cable.? The part you are asking about is the step response of your cable.? Consider the following.

On January 20, 2020 at 10:14 AM "tom verra via Groups.Io" <mnv73@...> wrote:


I would like to purchase one using paypal..as others have done..sent two emails to Maggie king with no response ?

On January 20, 2020 at 1:31 PM "Bob Albert via Groups.Io" < bob91343@...

wrote:

Mike,
Thanks for the information.? I did not buy the device because I have a
second nano that does okay.? But after reading your latest suggestion I
guess I'll buy the thing and see if I can upgrade without bricking the
unit.? It should also be a door to future upgrades.? Perhaps I can upgrade
the second nano via its USB port but that unit is flaky and turns itself
off without provocation.? It won't even turn on while the port is
connected, and sometimes even when not connected it fails.? Once on, I can
connect the port.? Then suddenly it behaves properly.
I did have thoughts of replacing the USB connector but it takes ability
that I lack.? I think over a dozen tightly spaced pins and limited access
and tools.
Bob
On Monday, January 20, 2020, 10:13:05 AM PST, n2msqrp < mstangelo@...

wrote:

Bryan,


Thanks. I thought it had to do with the mismatch between the coax and S11
port. I had a length of RG-6 handy and see the same effect with that 75
ohm cable and see the same effect. Since the loss of the Rg-6 is higher
the step responses is decreasing at a faster rate.


I have a 75 to 50 ohm pad. If I have time I may connect the pad to the S11
port, run a calibration using a 75 ohm load and run the test again.


Mike N2MS

Mike,


You need to think about what you are seeing in the time domain.? What the
software produces is the impulse response (the positive going blips) and
the step response (the steps in your plot) of the network attached.? The
steps are the result of multiple trips of a wave traveling through your
cable.? The part you are asking about is the step response of your cable.?
Consider the following.

On Mon, Jan 20, 2020 at 09:24 PM, hwalker wrote:

A similar discussion in Japanese (use Google translate or similar)
. His follow-up
discussions in January of this year are also an interesting read.

- Herb

I checked the content of this blog and some of the issues mentioned come from the wrong shield of the bad clone. Some modifications may not apply to a good NanoVNA. Our manufactured NanoVNA-H has good isolation.If you have better suggestions for improvements that can be feedback on github, we will try it and apply it to the next version of NanoVNA-H after verification, and send you the improved version to verify the modified effect.

hugen

Mike,

You need to think about what you are seeing in the time domain.? What the software produces is the impulse response (the positive going blips) and the step response (the steps in your plot) of the network attached.? The steps are the result of multiple trips of a wave traveling through your cable.? The part you are asking about is the step response of your cable.? Consider the following.

Mike,

You need to think about what you are seeing in the time domain.? What the software produces is the impulse response (the positive going blips) and the step response (the steps in your plot) of the network attached.? The steps are the result of multiple trips of a wave traveling through your cable.? The part you are asking about is the step response of your cable.? Consider the following.

Mike,

You need to think about what you are seeing in the time domain.? What the software produces is the impulse response (the positive going blips) and the step response (the steps in your plot) of the network attached.? The steps are the result of multiple trips of a wave traveling through your cable.? The part you are asking about is the step response of your cable.? Consider the following.

Hi Eric,
Thanks for your experiments to improve the nanoVNA.
And buy some flux remover to clean up the mess
Reinier

Mike,

You need to think about what you are seeing in the time domain. What the software produces is the impulse response (the positive going blips) and the step response (the steps in your plot) of the network attached. The steps are the result of multiple trips of a wave traveling through your cable. The part you are asking about is the step response of your cable. Consider the following.

On January 20, 2020 at 11:08 AM n2msqrp <mstangelo@...> wrote:


I've been checking my coax using NanaVNA Saver 0.2.2-1 on a NanoVNA-H with Hugen 0.4.5-4-g96e7efe firmware.

I have a piece of 75 ohm Commscope F-11 coax going to a junction box in the yard, I believe thet the far end is open.

I ran the TDR? function. The Estimated cable length 41.104m (134ft 10.3in) seems correct but I don't understand why I get this stair step graph with reflections at multiples of the 41.1m length.

On January 20, 2020 at 11:08 AM n2msqrp <mstangelo@...> wrote:


I've been checking my coax using NanaVNA Saver 0.2.2-1 on a NanoVNA-H with Hugen 0.4.5-4-g96e7efe firmware.

I have a piece of 75 ohm Commscope F-11 coax going to a junction box in the yard, I believe thet the far end is open.

I ran the TDR? function. The Estimated cable length 41.104m (134ft 10.3in) seems correct but I don't understand why I get this stair step graph with reflections at multiples of the 41.1m length.

On January 20, 2020 at 11:08 AM n2msqrp <mstangelo@...> wrote:


I've been checking my coax using NanaVNA Saver 0.2.2-1 on a NanoVNA-H with Hugen 0.4.5-4-g96e7efe firmware.

I have a piece of 75 ohm Commscope F-11 coax going to a junction box in the yard, I believe thet the far end is open.

I ran the TDR function. The Estimated cable length 41.104m (134ft 10.3in) seems correct but I don't understand why I get this stair step graph with reflections at multiples of the 41.1m length.