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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 |
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Re: Increasing measurement range (ohms) ?
Those well versed in the RF and microwave disciplines work with the 50-ohm
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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 --
*Dave - W?LEV* *Just Let Darwin Work* *Just Think* |
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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). |
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Re: Reduce Frequency Range
#hacking
Don't forget about the free Android audio spectrum analyzer apps you can run on your phone or tablet.?
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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. |
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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:
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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. |
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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.
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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. |
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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.
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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. |
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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.
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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 |
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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 |
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Re: Increasing measurement range (ohms) ?
Larry,
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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: |
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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 groundBoth 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 |
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Re: Reduce Frequency Range
#hacking
You can homebrew a decent low frequency bridge and use a couple of opamps to accomplish the task. I posted the operation in another post message and with an LT Spice schematic. Will see if I can locate.
Alan |
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Re: Reduce Frequency Range
#hacking
Probably, but you'd have to change the mixer coupling caps and the bridge circuit.? ?
??Here's your chance to play and let everyone know if it works!? Also, the output is a square wave so you'd need to deal with all sorts of harmonics or, instead you could mod the output to only send pink noise to the speakers and mix the return with the internal Freq source.? Sent from Rogers Yahoo Mail on Android On Fri, 13 Dec 2019 at 10:55 am, Webb, William<billwebb12@...> wrote: Is there any possibility of customizing the NanoVNA software for a lower frequency range? Yup, I wrote lower.? Aside from Ham radio HF applications, I would like to be able to characterize custom speaker crossovers.? The range would be, ideally, 20-20,000 Hz.? Can the hardware go that low? |
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Re: Reduce Frequency Range
#hacking
On Fri, 13 Dec 2019 07:55:17 -0800, you wrote:
Is there any possibility of customizing the NanoVNA software for a lower frequency range? Let me guess: no, it cannot be done. Rather use MLS with your PC soundcard. (Maximum Length Sequence) There are expensive commercial sytems like CLIO. For a entry level system have a look here: It starts with 50 euros. OE8UWW |
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Reduce Frequency Range
#hacking
Is there any possibility of customizing the NanoVNA software for a lower frequency range?
Yup, I wrote lower. Aside from Ham radio HF applications, I would like to be able to characterize custom speaker crossovers. The range would be, ideally, 20-20,000 Hz. Can the hardware go that low? |
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Re: F303 and 4" LCD for next generation NanoVNA
#circuit
#flash_size
#improvement
#enclosure
#battery
At the moment ADC1 can't read VBAT data correctly, and I can't get into DFUIf MCU is changed from original nanoVNA, then I guess also need change to NANOVNA_STM32_F072/board.h for BOOT_FROM_SYTEM_MEMORY_MAGIC_ADDRESS ADC1 address is buried in ChibiOS/os/common/ext/CMSIS/ST/* |
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Re: Increasing measurement range (ohms) ?
Yeah, there is flux all over and it looks like someone learning to solder assembled it. \_('_')_/
Sent from Rogers Yahoo Mail on Android On Fri, 13 Dec 2019 at 9:51 am, Oristo<ormpoa@...> wrote: Hi Larry - I picked up a bridge from the eBay link above.Sorry to learn that;? I suppose only ones from Ukraine are better. At least it's fixable.Leaving 100 Ohm resistors NOT connected in parallel improves sensitivity for differences at higher impedances, but fixing coax terminations thru ferrite beads is necessary. |
Oristo
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