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Re: 30MHz and below

 

Not enough memory

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK
Re: CAL -> RESET -> CALIBRATION clarification...

 

Ah, grazie Maurizio! I suspected it had to be something I missed..
Saluti da sunny Melbourne, Australia..
lm
Re: CAL -> RESET -> CALIBRATION clarification...

 

On Sat, Dec 14, 2019 at 07:33 AM, Luigi Mantuano wrote:


Hello again,
earlier today I finally loaded hugen's v0.4.0-3, AA-4 traces (
NanoVNA-H_20191125_AA.dfu) FW on my nV... all looked good but when I went to
set up and store the 5th calibrated range in C4, there is no C4! there is no
SAVE 4 nor RECALL 4 tabs, only 0, 1, 2 and 3....
Honestly I can't remember (not paid nuff attention perhaps) whether my earlier
FW version/s had 5 memory locations for cal data, as per documentation.
Please forgive my clumsiness if this turns out to be a triviality or if I
missed the relevant bit of info.
TIA
Luigi M
Hi Luigi , from message #7400 about the firmware version 4.0.3 AA

QRP and Oristo wrote:
"it has larger font, so it cannot show full frequency and measured value result and cut-off part of the value"

"4 calibration SAVE areas instead of 5. On the other hand, Hugen maintains code inline that is neither in edy555 nor QRP firmware, so presumably more responsive.
Other space was cleared in previous release (4.0) by
eliminating shell commands: DUMP, SCANRAW, COLOR"

Best Regards
Maurizio IZ1MDJ
Re: 30MHz and below

 

Would it be possilbe to have more store positions for settings? 9 would be great for HF bands. Does anyone now if the limitation is on the hardware or just on the firmwares available?

George, SV3QUP
Re: CAL -> RESET -> CALIBRATION clarification...

 

Hello again,
earlier today I finally loaded hugen's v0.4.0-3, AA-4 traces ( NanoVNA-H_20191125_AA.dfu) FW on my nV... all looked good but when I went to set up and store the 5th calibrated range in C4, there is no C4! there is no SAVE 4 nor RECALL 4 tabs, only 0, 1, 2 and 3....
Honestly I can't remember (not paid nuff attention perhaps) whether my earlier FW version/s had 5 memory locations for cal data, as per documentation.
Please forgive my clumsiness if this turns out to be a triviality or if I missed the relevant bit of info.
TIA
Luigi M
Re: Reduce Frequency Range #hacking

 

this maybe a oldie buts it is extremely powerful
Re: Reduce Frequency Range #hacking

 

DL4YHF's "Spectrum Lab" (sound card data handler and spectrum analyzer)

looks a bit overwhelming at first, but it is really not that hard to use. It is very well done with very powerful control and post processing and, importantly, is well supported by the author. I have used it a lot, as have many others.
Bob W7PUA
Re: Increasing measurement range (ohms) ?

 

Those well versed in the RF and microwave disciplines work with the 50-ohm
impedance. Sure, the TV people work with 75-ohms, not much different. But
for very high and low Z's, use the Smith Chart. It can be normalized to
any impedance you desire. Everything I have as a rather extensive lab of
RF test equipment (mostly HP) and have worked with throughout my career in
RF design and EMC/RFI is 50-ohms. The Smith Chart is a wonderful tool for
working for something other that 50-ohms, Normalize it to 200
ohms.......you have a 200-ohm chart. Normalize it to 2-ohms.......you have
a 2-ohm chart. I see absolutely no need for a wider resistance measurement
window. We're not dealing with a DC resistance measurement !

Dave - W?LEV

On Fri, Dec 13, 2019 at 10:58 PM <roncraig1@...> wrote:

You are not going to be able to improved reading of high impedance very
much as the primary limitation is the 50 ohm impedance bridge and signal
level differences get very small at the higher load impedance.(refer to
right hand, high Z side point of Smith chart. The difference in reflection
coeff. is very small at higher Z).

Probably the best thing to improve unit's overall accuracy is the
replacement of the cheap thick film 49.9 ohm chip resistors (EIA96 marking
'68X') in the input bridge with 50.0 ohm 0.1% tolerance high frequency thin
film resistors. They are about $1.50 each at Mouser Elect. for Vishay
FC0603E50R0BTBST1 part number.

As for baluns, there are some good MiniCircuits baluns. TCM1-43X+ for
1:1. You will lose some low frequency operating range due the low end
limit of the balun, down to about 10 MHz. The N1201SA UV RF Vector
Impedance meter uses a similar balun from the impedance bridge to SA612
mixer with upper freq operation to 2700 MHz with fundamental Tx frequency
and harmonic Rx down mixing. (uses a higher freq Analog Devices
synthesizer).



--

*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
Re: Increasing measurement range (ohms) ?

 

You are not going to be able to improved reading of high impedance very much as the primary limitation is the 50 ohm impedance bridge and signal level differences get very small at the higher load impedance.(refer to right hand, high Z side point of Smith chart. The difference in reflection coeff. is very small at higher Z).

Probably the best thing to improve unit's overall accuracy is the replacement of the cheap thick film 49.9 ohm chip resistors (EIA96 marking '68X') in the input bridge with 50.0 ohm 0.1% tolerance high frequency thin film resistors. They are about $1.50 each at Mouser Elect. for Vishay FC0603E50R0BTBST1 part number.

As for baluns, there are some good MiniCircuits baluns. TCM1-43X+ for 1:1. You will lose some low frequency operating range due the low end limit of the balun, down to about 10 MHz. The N1201SA UV RF Vector Impedance meter uses a similar balun from the impedance bridge to SA612 mixer with upper freq operation to 2700 MHz with fundamental Tx frequency and harmonic Rx down mixing. (uses a higher freq Analog Devices synthesizer).
Re: Reduce Frequency Range #hacking

 

Don't forget about the free Android audio spectrum analyzer apps you can run on your phone or tablet.?
They might even run on Chrome under arcwelder.?



On Fri, 13 Dec 2019 at 5:16 PM, Bob Albert via Groups.Io<bob91343@...> wrote: I will have to look around; do you have a link to a specific audio SA?? Basically I want it to measure distortion of an audtio oscillator.
Bob

On Friday, December 13, 2019, 01:52:57 PM PST, stone_ridge_road <xdavid@...> wrote:


There are various free PC applications that use the sound card for an
audio spectrum analyzer.? If you use a good quality sound card (flat
response, low noise level) I would think that the results would be
pretty good.? The sensitivity is typically good enough that there are
even VLF receiver applications out there.

73,
Dave?? AB7E



On 12/13/2019 12:56 PM, Bob Albert via Groups.Io wrote:
An audio VNA would be great, as would be an audio SA.? I have use for the latter but it's not a common item.
Bob K6DDX
Re: Reduce Frequency Range #hacking

 

The applications (I've used more than one) that I've used in the past are pretty old by now, so I found this supposedly more recent list of free applications:



However, this one looks pretty powerful and the standard version is only $30 US dollars if you buy it before December 15.



73,
Dave?? AB7E

On 12/13/2019 3:15 PM, Bob Albert via Groups.Io wrote:
I will have to look around; do you have a link to a specific audio SA?? Basically I want it to measure distortion of an audtio oscillator.
Bob
On Friday, December 13, 2019, 01:52:57 PM PST, stone_ridge_road <xdavid@...> wrote:
There are various free PC applications that use the sound card for an
audio spectrum analyzer.? If you use a good quality sound card (flat
response, low noise level) I would think that the results would be
pretty good.? The sensitivity is typically good enough that there are
even VLF receiver applications out there.

73,
Dave?? AB7E



On 12/13/2019 12:56 PM, Bob Albert via Groups.Io wrote:
An audio VNA would be great, as would be an audio SA.? I have use for the latter but it's not a common item.
Bob K6DDX
Re: Reduce Frequency Range #hacking

Bob Albert
 

I will have to look around; do you have a link to a specific audio SA?? Basically I want it to measure distortion of an audtio oscillator.
Bob

On Friday, December 13, 2019, 01:52:57 PM PST, stone_ridge_road <xdavid@...> wrote:


There are various free PC applications that use the sound card for an
audio spectrum analyzer.? If you use a good quality sound card (flat
response, low noise level) I would think that the results would be
pretty good.? The sensitivity is typically good enough that there are
even VLF receiver applications out there.

73,
Dave?? AB7E



On 12/13/2019 12:56 PM, Bob Albert via Groups.Io wrote:
An audio VNA would be great, as would be an audio SA.? I have use for the latter but it's not a common item.
Bob K6DDX
Re: Reduce Frequency Range #hacking

 

There are various free PC applications that use the sound card for an audio spectrum analyzer.? If you use a good quality sound card (flat response, low noise level) I would think that the results would be pretty good.? The sensitivity is typically good enough that there are even VLF receiver applications out there.

73,
Dave?? AB7E

On 12/13/2019 12:56 PM, Bob Albert via Groups.Io wrote:
An audio VNA would be great, as would be an audio SA.? I have use for the latter but it's not a common item.
Bob K6DDX
Re: Reduce Frequency Range #hacking

Bob Albert
 

It would be nice if someone would produce this unit for sale at a reasonable price.? An audio VNA would be great, as would be an audio SA.? I have use for the latter but it's not a common item.
Bob K6DDX

On Friday, December 13, 2019, 11:36:00 AM PST, Bob Larkin <bob@...> wrote:

It is a project, rather than an ebay buy, but

does a quality set of measurements from 10 Hz to 40 kHz.? It is all open
hardware and software.

Note that at lower frequencies one can find impedance by directly
measuring V and I (magnitude and phase) and calculating V/I.? That is
the usual method and is more accurate and simpler to do.

There are also some very simple implementations of the impedance
measurement part: G. R. Steber, WB9LVI, ¡°A Low Cost Automatic Impedance
Bridge,¡± QST Oct. 2005, pp. 36?39.? Also, ref 3 of the URL above.

A side note is that the AVNA in the URL above is programmable from a
serial link and prime for adaptation to the control software such as
wonderful nanoVNA-saver.? Anyone interested in doing that?? I would be
happy to support that with firmware changes to the AVNA, as needed.

Bob? W7PUA
Re: Reduce Frequency Range #hacking

 

A couple more notes. The reference 3 for Z measurement is in the QEX article


Also, there is a support group
/g/AVNA1

Bob W7PUA
Re: Reduce Frequency Range #hacking

 

It is a project, rather than an ebay buy, but

does a quality set of measurements from 10 Hz to 40 kHz. It is all open hardware and software.

Note that at lower frequencies one can find impedance by directly measuring V and I (magnitude and phase) and calculating V/I. That is the usual method and is more accurate and simpler to do.

There are also some very simple implementations of the impedance measurement part: G. R. Steber, WB9LVI, ¡°A Low Cost Automatic Impedance Bridge,¡± QST Oct. 2005, pp. 36?39. Also, ref 3 of the URL above.

A side note is that the AVNA in the URL above is programmable from a serial link and prime for adaptation to the control software such as wonderful nanoVNA-saver. Anyone interested in doing that? I would be happy to support that with firmware changes to the AVNA, as needed.

Bob W7PUA
Re: Increasing measurement range (ohms) ?

 

Larry,

Do we know if the clone bridges us the correct ferrites? I would stick with the transverters store version.

< >

Order and active probe or active while y=while you are there.

Mike N2MS

On December 12, 2019 at 8:44 PM Larry Rothman < nlroth@... mailto:nlroth@... > wrote:


On Sat, Nov 16, 2019 at 12:59 PM, Oristo wrote>

> > A green (not blue) ~US$10 reflection bridge
e.g. from eBay
with matched SMA references (want a matched pair to calibrate nanoVNA CH1)

> Oristo,
I picked up a bridge from the eBay link above. The build quality is poor and the 2, 100 ohm resistor pairs are each not in parallel. So even though the board is green, it's no better than one of those blue boards with the same issues.

At least it's fixable.
I've attached a couple of photos.
Re: Increasing measurement range (ohms) ?

KV5R
 

On Fri, Dec 13, 2019 at 09:01 AM, Dale Parfitt wrote:
I am not sure that makes it an effective balun. Or maybe at best a voltage balun, but not a current balun - which is what antennas require. As I recall, it is not possible to make a current balun, other than 1:1 ratio on a single core.
erik@ wrote: Its both - 1:9 transformer with the 9 side not connected to ground
Both Correct.
Per the Coilcraft datasheet, it's a regular transformer with primary and secondary windings, with high side isolated from ground. Nooelec calls it a "balun" (marketing?), but Coilcraft accurately calls it a "wideband transformer."
For Andy's stated application, it doesn't matter if it's a proper "balun" or not, just an impedance transformer with sufficient bandwidth. I proved it will transform 4500 to 500, with a flat response from 1-31MHz, so it should work to measure the feed-point impedance of an end-fed half-wave HF antenna.
As for common-mode rejection, it's likely very low for this device, but if it becomes a problem, is easily remedied by winding the li'l sma-sma cable a few times through a toroid, thus preceding the transformer with a CM choke.
73, --kv5r
Re: Increasing measurement range (ohms) ?

 

Please, guys, when you speak of a 1:n transformer. always specify whether n
represents voltage (turns ratio) or impedance. It is often not clear from context.

Thanks,

Dana
Re: Reduce Frequency Range #hacking

 

See msg #1252

Alan
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