TDR (Cable Test Mode) Fault

[John G3PQA]

My Sark-110 is working normally in Scalar mode, but giving very poor readings in Cable Test Mode.

The screen shows Imp and Step on the correct scales, but when scanning Open and Short there is very little (1mm only) up and down Step deflection.

I have reloaded the firmware and recalibrated my test lead 0.5-100MHz but the fault is the same.

What might be causing this problem?

Thanks

John

 

[Melchor Varela]

Hi John,

Do you see the typical spiral pattern when measuring the cable and performing the readings using Smith Chart mode with a sufficiently large span?

Best regards,

Melchor EA4FRB 

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[Terry Perdue]

Good to see you’re still around to answer questions, Melchor. I was sorry to see the SARK-110 discontinued. It’s still my favorite pocket gadget.

Sent from my iPhone

On Oct 5, 2023, at 1:11 PM, Melchor Varela <melchor...@gmail.com> wrote:



To view this discussion on the web visit https://groups.google.com/d/msgid/sark110/CAN84_Dc61AQYDwVR%3DDfoCk96q_%3DLHCv1OfP3H3V8j5xsFAL42g%40mail.gmail.com.

[Edward Mccann]

Concur.

Ed McCann

AG6CX

On Oct 5, 2023, at 1:55 PM, Terry Perdue <k8...@comcast.net> wrote:

Good to see you’re still around to answer questions, Melchor. I was sorry to see the SARK-110 discontinued. It’s still my favorite pocket gadget.

To view this discussion on the web visit https://groups.google.com/d/msgid/sark110/B17F0060-8F51-4ABB-8A2E-C7ACC4242449%40comcast.net.

[John G3PQA]

Hi Melchor,

Thanks, I will check later today and report back.

Hi Edward and Terry,

Agree the Sark-110 software, shirt pocket size, and versatility make it excellent. I still think it is the best HF-lowerVHF analyser for field and shack use with Sarkplots. The TDR function is particularly good thanks to Melchor's excellent zoom function with choice of scales .

There is even a choice of firmware, I still prefer the 9 series myself but others must like the way that the 10 series is laid out I guess.

73

John

[John G3PQA]

-------- Forwarded Message --------
Subject:
Re: TDR (Cable Test Mode) Fault
Date:
Sat, 7 Oct 2023 08:50:56 +0200
From:
Melchor Varela

To:
John G3PQA

Hi John,

As far as I remember there are no settings in frequency domain modes that would affect TDR mode. It is possible that indeed, the firmware was corrupted. To prevent this to some extent, it is convenient to check the health of the internal disk drive before the update operations.

Anyway, I'm glad to know that the issue no longer appeared.

Kind regards,

Melchor EA4FRB 

El sáb, 7 oct 2023 5:04 a. m., John G3PQA  escribió:

Hi Melchor,
Google Groups will not let me post this reply, so am sending direct.
Many thanks again for your help.
73
John

-------- Forwarded Message --------
Subject:
Re: TDR (Cable Test Mode) Fault
Date:
Sat, 7 Oct 2023 04:00:04 +0100
From:
John G3PQA

 

Hi Melchor,

 I changed to the Smith Chart function and opened up the frequency range to 0.5-100MHz as you recommended .

Sweeping 3.5m of 75ohm coax open at the end appears to show the usual spiral pattern. (see below)

Also the TDR Cable Test function on the same cable now appears to work normally. (see below)

The only thing I have changed today apart from the Smith Chart frequency range (previously 4MHz) was to reload my 9.5b firmware, so perhaps the firmware load before was corrupted?

Are there any settings made in Scalar or Smith modes that can affect TDR mode?

Anyway it all now appears to be working normally.

73

John

 

[John G3PQA]

TDR sweep of 3.5m. of 2003 coax open at end (now appears normal)