Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
The best way would be to use a quarter-wave section of 62 ohm cable.
Lacking that, you may have to build some sort of antenna tuner.
73, Zack W9SZ
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On Thu, Jul 1, 2021 at 7:13 AM Mikek <amdx@...> wrote: Testing a couple of TV antennas for Signal strength and just curious about
what they might look at on the NanoVna.
I'll be looking at them through about 70 ft of RG-6 and a SMA to F adapter.
Measuring from 180MHz to 610MHz.
Pretty much a novice here.
Mikek
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
Good question, I'm sure part of it involves no 50-ohm cables, and probably calibration with a 75-ohm load termination, but there may be some other corrections to VSWR, etc.
Let us know!
73, Willie N1JBJ
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On Jul 1, 2021, at 8:13 AM, Mikek <amdx@...> wrote:
Testing a couple of TV antennas for Signal strength and just curious about what they might look at on the NanoVna.
I'll be looking at them through about 70 ft of RG-6 and a SMA to F adapter.
Measuring from 180MHz to 610MHz.
Pretty much a novice here.
Mikek
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impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
Testing a couple of TV antennas for Signal strength and just curious about what they might look at on the NanoVna.
I'll be looking at them through about 70 ft of RG-6 and a SMA to F adapter.
Measuring from 180MHz to 610MHz.
Pretty much a novice here.
Mikek
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Re: Measuring 49:1 ferrite transformers
An excellent piece of work Gary.
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The other hams have good ideas but I am older now and climbing up the hatch and into a HOT attic is not going to happen! I just set the nanovna to cover 3MHz to 30MHz and scanned SWR of each to find which were HF or not. From those that were HF I checked each band for SWR then did the same for the non HF. Worked well.
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Re: New to NanoVna - Newest version?
Just be sure not to deal with Nooelec.
WL
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-----Original Message----- From: Roy <roy@...> To: nanovna-users < [email protected]> Date: Wednesday, 30 June 2021 2:02 PM EDT Subject: Re: [nanovna-users] New to NanoVna - Newest version? On Tuesday 29 June 2021 10:51:25 pm Bill K wrote: Hello, I've been considering purchasing one of these for some time. I'm not an engineer or anything even close, but I am an amateur radio operator who enjoys experimenting with antennas, and this seems like a really useful tool. However, I am unsure of which model is most current. I understand that the latest is the NanoVna-H4, but none of the vendors listed on nanovna.con have this model in stock. It appears that Aursinc has the F version in stock on Amazon, I am not sure if there is much difference for my purposes, or if I should wait for the H4 to come back in stock. Also, is it safe to assume that the vendors listed through nanovna.com are selling good quality items? I'm a bit leery of buying a cheap clone from an unknown source. I bought my H4 from R&L, along with adapters to PL259 and BNC, and am quite happy with what I ended up with... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
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Re: New to NanoVna - Newest version?
On Tuesday 29 June 2021 10:51:25 pm Bill K wrote: Hello, I've been considering purchasing one of these for some time. I'm not an engineer or anything even close, but I am an amateur radio operator who enjoys experimenting with antennas, and this seems like a really useful tool. However, I am unsure of which model is most current. I understand that the latest is the NanoVna-H4, but none of the vendors listed on nanovna.con have this model in stock. It appears that Aursinc has the F version in stock on Amazon, I am not sure if there is much difference for my purposes, or if I should wait for the H4 to come back in stock. Also, is it safe to assume that the vendors listed through nanovna.com are selling good quality items? I'm a bit leery of buying a cheap clone from an unknown source. I bought my H4 from R&L, along with adapters to PL259 and BNC, and am quite happy with what I ended up with... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin
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Measuring 49:1 ferrite transformers
I did a few systematic experiments using my nanoVNA to measure the properties of 49:1 transformers. It helped me to understand these beasts better... Write-up here:
Cheers,
Gary AF7NX
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Re: RETURN LOSS thoughts de k3eui
It's the same in other fields.? In optics, density is the negative log of the transmission, so something that transmit 0.1 of the incident intensity is a positive density of 1.? Density is like loss, the more of it, the larger (more positive) the number.
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On Wednesday, June 30, 2021, 6:08:59 AM MDT, Barry K3EUI <k3euibarry@...> wrote:
I had not anticipated this would lead to so many comments.
Thank you for great insights.
Maybe it feels more correct if we just say? RETURN? (S11) and leave the word "loss" out.
I mean for an antenna, I'd like the S11 signal to be very very small, because I hope the forward signal is turned in an EM wave, and not much is relfected back towards the source.
I ran into another interesting concept while giving a "talk" on the Nano VNA.
WHAT IS THE NET CHARGE ON A BATTERY?
WHAT IS THE NET CHARGE ON AN UNCHARGED CAPACITOR?
WHAT IS THE NET CHARGE ON A CHARGED CPACITOR?
WHAT IS THE NET CHARGE ON AN ANTENNA WHILE RADIATING AND EM WAVE?
This led to another question:
At any given moment, when generating an EM wave, is one-half of a dipole negative, and the other half positively charged?? ? What is the NET charge then on the whole antenna?
That was interesting.....? all because of a talk on Nano VNA.
This little gadget brings to life many ideas about our understanding of basic physics.
de? k3eui
de k3eui
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Re: Modify Original Nanovna for easy DFU mode like the H4
#dfu
#mods
Thx for this very helpful hack - this helps me a lot during FW development.
But it is sufficient to add the wire (easy task), no need to change the resistor R5 from 1K (original) to 5K (as H4) - this is more difficult, especially if you do not have this SMD value at hand :). I checked the schematics, the JP P1 connects BOOT0 directly to Vdd, so it doesn't harm if you connect via 1K to Vdd.
Martin
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Re: RETURN LOSS thoughts de k3eui
I had not anticipated this would lead to so many comments.
Thank you for great insights.
Maybe it feels more correct if we just say RETURN (S11) and leave the word "loss" out.
I mean for an antenna, I'd like the S11 signal to be very very small, because I hope the forward signal is turned in an EM wave, and not much is relfected back towards the source.
I ran into another interesting concept while giving a "talk" on the Nano VNA.
WHAT IS THE NET CHARGE ON A BATTERY?
WHAT IS THE NET CHARGE ON AN UNCHARGED CAPACITOR?
WHAT IS THE NET CHARGE ON A CHARGED CPACITOR?
WHAT IS THE NET CHARGE ON AN ANTENNA WHILE RADIATING AND EM WAVE?
This led to another question:
At any given moment, when generating an EM wave, is one-half of a dipole negative, and the other half positively charged? What is the NET charge then on the whole antenna?
That was interesting..... all because of a talk on Nano VNA.
This little gadget brings to life many ideas about our understanding of basic physics.
de k3eui
de k3eui
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Re: RETURN LOSS thoughts de k3eui
Lou, don't forget Hz for Hertz!
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Re: Where does this noise/instability come from at and around 300MHz?
Need save config
Config-Save
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On 6/29/2021 9:38 PM, Dave (NK7Z) wrote: With an attic full of antennas that have all coax running to a box in the shack, I no longer knew which cable came from which antenna. I had a similar problem. I placed various value resistors on the coax in the shack where it was easy to work, (50,10,220 etc), then took an ohmmeter in the attic and identified each line. Only one trip in the attic (confined space) and I was done. 73, Joe, K1ike
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Re: RETURN LOSS thoughts de k3eui
Negative loss is gain. Coax loss per foot is X not negative X. Attenuation is X not negative X.
A really, really, REALLY, simplistic example. I lost 20 pounds. I didn't loose negative 20 pounds.
As someone else pointed out, there are numerous examples, sometimes in the same article, getting return loss wrong. That only adds to the confusion.
Ron
N4XD
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Re: Where does this noise/instability come from at and around 300MHz?
Disable calibration, set frequency range 280-300MHz
See frequency point there start this
Change THRESHOLD frequency to this (avaible in expert menu settings).
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Re: Simple Latest Firmware list available and links to download?
Hello! congratulations on your purchase! It is very interesting to look at the PCB of your NanoVNA v3. 5! If of course it does not bother you! Sincerely yours!
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New to NanoVna - Newest version?
Hello, I've been considering purchasing one of these for some time. I'm not an engineer or anything even close, but I am an amateur radio operator who enjoys experimenting with antennas, and this seems like a really useful tool. However, I am unsure of which model is most current. I understand that the latest is the NanoVna-H4, but none of the vendors listed on nanovna.con have this model in stock. It appears that Aursinc has the F version in stock on Amazon, I am not sure if there is much difference for my purposes, or if I should wait for the H4 to come back in stock. Also, is it safe to assume that the vendors listed through nanovna.com are selling good quality items? I'm a bit leery of buying a cheap clone from an unknown source.
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When I replace an outlet near a table or counter and downstream from a GFCI outlet in the kitch
ebay or amazon search forusb outlet wall
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On Tuesday, June 29, 2021, 9:37:48 PM EDT, Dave Merrill <r390a.urr@...> wrote: I repurpose old micro-USB cables and 5 V chargers with these USB-C adapters: Adding a sleeve of shrink tubing to cover the joint ensures they don't easily come apart. Dave N9ZC On Tue, Jun 29, 2021, 12:52 PM Jim Lux <jim@...> wrote: On 6/29/21 8:01 AM, Mikek wrote:
I pulled my NanoVNA-H out just to charge it, it has been a while since I used it. It powers up fine and the indicator says the battery is low.
I see the connector is not the usual micro USB on my phone, but is a USB-C. Did I get a charger with my unit, that I have lost?
I have no clue how I charger my Nano! I do have the 10" USB-C cable. I bought it from R&L.
? ? Thanks Guys
? ? Mikek Mine didn't have a charger but had a USB-C cable - you charge it using
any USB-C (or USB-A) charger.? I've used both: MacBook Pro which has
USB-C, but also has adapters to USB-A - I've also charged it from a
standalone charger.
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Short out the antenna to the coax ground, using a clip lead, then use the nano to locate the shorted antenna, or put a 50 ohm resistor across the coax, and look for a perfect match at most frequencies.
Or short out the coax end, and look for a short at the feedpoint, using an ohm meter.
73, and thanks,
Dave (NK7Z)
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
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On 6/29/21 6:26 PM, Gary wrote: Hello Richard,
I have exactly the same problem here.? I have some twenty antennas in the attic.? The house is a 120 years old Victorian so the attic is huge.? We've owned it the last twenty-one years and I have coax running everywhere up there.? I too had labelled and charted everything initially but years of swapping this to that and that to another has resulted in total chaos..hi..hi.? I have a NanoVNA-F.? I am wondering just exactly how you went about using your Nano to identify each antenna?? Thanks.
73,
Gary - W6GVS
At 08:51 PM 6/29/2021, you wrote:
I purchased a NANOVNA-H some time ago to learn and hopefully solve a problem.? With an attic full of antennas that have all coax running to a box in the shack, I no longer knew which cable came from which antenna. Well labeled 25 years ago but four of the five are no longer readable. The Nano solved the problem along with some great guides from this group and nanovna-saver I have identified all four with their SWR patterns. TNX
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Alistair - M5ASF
Richard Clemens
infomet2003
Lou W7HV
Ho-Ro
Barry K3EUI