Re: Cable Fault Detection
Jim...All good points.
Yes, I have been thinking about a dedicated nanovna and fixture and the various options needed for different cable types. For the multi-channel snakes the VF is pretty similar as the construction and materials is similar. This would be the main use. And the stimulus scan frequencies will probably require changing as well.
I would like to make this as easy for individuals with varing technical experience. It might necessitate a PC connection but I have not researched that aspect...very new project.
Single mic cables can have a VF much lower, I've measured some less than 50%.
And yes the impedance is as you mention although manufacturers don't always specify except for AES/EBU whis in nominally 110 Ohms.
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Re: Cable Fault Detection
On 6/21/23 8:05 PM, Joe wrote: I was just trying to point out that if you have a choice between using a short or open on any device, the short would minimize or eliminate interference that might enter the end of the cable.
Joe
On 6/21/2023 9:56 PM, Geoff Peters - AB6BT wrote:
Joe.. What I'm trying to do is locate a short or open in a multi-channel audio snake. I really can't afford the high priced spread...
You might make up some XLR cal loads - Open's easy. Short, and I'd go for a 100 or 120 ohm load, since it's probably shielded twisted pair. But yeah, if you're looking for a fault somewhere in the middle, then shorting the far end minimizes hassles. I assume you're not looking for a channel to channel short. This is great non RF application for the NanoVNA.. you should write up how you did it and what you found out. WIth these sorts of things fixturing is what it's all about. If you've got a snake with XLR on both ends, then cobbling up some adapters is probably a good thing. Propagation speed in a multichannel audio cable, whether shielded twisted pair or multiple coax is going to be something you'll have to figure out. But you know the physical length. FWIW, mic cables aren't 50 ohms, but you knew that.
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Re: Cable Fault Detection
On 6/21/23 6:56 PM, Geoff Peters - AB6BT wrote: Joe.. What I'm trying to do is locate a short or open in a multi-channel audio snake. I really can't afford the high priced spread...
real mode will do you. I've used the NanoVNA on Cat 5 network cables. SMA to BNC: BNC to clipleads (EZ-Hook variety).
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Re: Cable Fault Detection
On 6/21/23 5:41 PM, Geoff Peters - AB6BT wrote: Roger...I was in Logmag mode. I'll try Real tomorrow
Jim...In Logmag mode the short and open appear identical as far as I can tell
Log mag is *always positive* (it's absolute value).. Yeah, you need to be in a linear signed mode
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Re: Cable Fault Detection
I was just trying to point out that if you have a choice between using a short or open on any device, the short would minimize or eliminate interference that might enter the end of the cable.
Joe
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On 6/21/2023 9:56 PM, Geoff Peters - AB6BT wrote: Joe.. What I'm trying to do is locate a short or open in a multi-channel audio snake. I really can't afford the high priced spread...
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Re: Cable Fault Detection
Joe.. What I'm trying to do is locate a short or open in a multi-channel audio snake. I really can't afford the high priced spread...
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Re: Cable Fault Detection
I do fault locating with the Anritsu SiteMaster and the CellMaster. I prefer to use a short when testing because it seals off the end of the cable and avoids/reduces interference. This can help when testing on a heavily RF populated site.
Joe
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On 6/21/2023 8:13 PM, Jim Lux wrote: It should work identically - short and opens have 180 degree difference in the phase of the reflection, and that shows up in the synthetic TDR from the frequency sweep.
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Re: Cable Fault Detection
Roger...I was in Logmag mode. I'll try Real tomorrow
Jim...In Logmag mode the short and open appear identical as far as I can tell
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Re: Cable Fault Detection
On 6/21/23 2:22 PM, Geoff Peters - AB6BT wrote: I realize this is similar to a recent topic but a bit different.
As the "TDR" function in the nanovan is not actually a time-domain process, is there a wat to differentiate between a short or open fault in a cable?
I have previously built a generator which can produce a very short pulse or a step with fast risetime. I have used it in conjunction with a scope as a TDR. It works reasonable well and you can clearly see an open or short in a cable.
Is there a way to replicate tis with a nanovna? It should work identically - short and opens have 180 degree difference in the phase of the reflection, and that shows up in the synthetic TDR from the frequency sweep.
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On Wed, Jun 21, 2023 at 02:45 PM, Robert Rose wrote:
This is a "where is Waldo" on the menu spider-web question. How do start a
rescan after I change parameters? Is there an FAQ that beginners should read?
A "NanoVNA for Dummies" book that you can recommend?
The Files section of this group contains an "Absolute Beginners Guide to the NanoVNA" Roger
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Re: Cable Fault Detection
If you turn on Transform and select Low Pass Impulse you are in "TDR mode". You need to set trace to "Real" and then you will see the difference between a short and an open.
Roger
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Re: Additional information on Nano VNA
On Wed, Jun 21, 2023 at 02:52 PM, Robert Rose wrote:
On Tue, Jun 11, 2019 at 07:52 PM, Frank S wrote:
Is there a way to tell what rev the firmware is?
HOME MENU->CONFIG->VERSION
Why necropost? Lots of current discussions in this group. Roger
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I should have said that type 43 reads like an open circuit .
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On Wed, Jun 21, 2023 at 1:44?PM Gene Ruff <ruff.gene@...> wrote: a useful hint when identifying torrides type 31 has resistance across the
surface . type 43 has none. Different materials.
On Wed, Jun 21, 2023 at 1:23?PM W0LEV <davearea51a@...> wrote:
43 or 31 material are appropriate for HF applications. 43 is better for
20-meters upward and 31 material is best for 160 through 40 meters. If
you
are sure you have 43 material, there really is no reason to test the
toroids.
Dave - W0LEV
On Wed, Jun 21, 2023 at 12:48?PM Kurt Heernaert <on4cgw@...> wrote:
Dears,
FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids to
be sure that I have the correct ones for HF UNUN?
any info is welcome
73,
Kurt
--
*Dave - W?LEV*
--
Dave - W?LEV
--
*Gene Ruff*
--
*Gene Ruff*
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Re: Translated instructions
All the units are based on the same hardware. This from "A Guide to the NanoVNA":
The current design of the NanoVNA and the name was created several years ago by a Japanese ham under the pseudonym ¡°edy555¡±. His first design ideas with a different DDS (frequency generator) seem to date back to 2013, but the current design with a significantly reduced parts count and based on the Si5351A was published by him in 2016. Edy555 himself references a German kit, the VNWA3 which was based on the concept of using a cheap computer soundcard, published by Tom Baier, DG8SAQ in the Mar/Apr 2007 issue of QEX ("A Low Budget Vector Network Analyzer for AF to UHF"). In the summer of 2016, edy555 announced to produce the NanoVNA, which was apparently done afterwards, but the kits were predominantly sold in Japan. Edy555 was also involved in the original firmware and continues to support the firmware (see chapter Two). He decided to open-source hardware and firmware to avoid bad clones, which undoubtedly was key to future development and the current popularity of the NanoVNA. It was not until a Chinese ham, Gen Hu (pseudonym ''hugen'') adapted the design slightly by changing the power supply and started to mass market the NanoVNA, that the device created international interest. In agreement with Edy555, hugen sells his product under the name NanoVNA-H. Hugen also runs his version of the firmware.
Schw?rzler, Christoph; Schw?rzler, Maximilian. A guide to the NanoVNA (pp. 9-10). Kindle Edition.
Bob
KN6UXD
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Re: Translated instructions
Google search: NanoVNA menu images
Bob
KN6UXD
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Re: Additional information on Nano VNA
On Tue, Jun 11, 2019 at 07:52 PM, Frank S wrote:
Is there a way to tell what rev the firmware is?
HOME MENU->CONFIG->VERSION Bob KN6UXD
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This is a "where is Waldo" on the menu spider-web question. How do start a rescan after I change parameters? Is there an FAQ that beginners should read? A "NanoVNA for Dummies" book that you can recommend?
Thank you,
Bob
KN6UXD
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I realize this is similar to a recent topic but a bit different.
As the "TDR" function in the nanovan is not actually a time-domain process, is there a wat to differentiate between a short or open fault in a cable?
I have previously built a generator which can produce a very short pulse or a step with fast risetime. I have used it in conjunction with a scope as a TDR. It works reasonable well and you can clearly see an open or short in a cable.
Is there a way to replicate tis with a nanovna?
|
a useful hint when identifying torrides type 31 has resistance across the
surface . type 43 has none. Different materials.
toggle quoted message
Show quoted text
On Wed, Jun 21, 2023 at 1:23?PM W0LEV <davearea51a@...> wrote: 43 or 31 material are appropriate for HF applications. 43 is better for
20-meters upward and 31 material is best for 160 through 40 meters. If you
are sure you have 43 material, there really is no reason to test the
toroids.
Dave - W0LEV
On Wed, Jun 21, 2023 at 12:48?PM Kurt Heernaert <on4cgw@...> wrote:
Dears,
FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids to
be sure that I have the correct ones for HF UNUN?
any info is welcome
73,
Kurt
--
*Dave - W?LEV*
--
Dave - W?LEV
--
*Gene Ruff*
|
43 or 31 material are appropriate for HF applications. 43 is better for
20-meters upward and 31 material is best for 160 through 40 meters. If you
are sure you have 43 material, there really is no reason to test the
toroids.
Dave - W0LEV
toggle quoted message
Show quoted text
On Wed, Jun 21, 2023 at 12:48?PM Kurt Heernaert <on4cgw@...> wrote: Dears,
FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids to
be sure that I have the correct ones for HF UNUN?
any info is welcome
73,
Kurt
-- *Dave - W?LEV*
--
Dave - W?LEV
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Roger Need