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Re: mini vs nano ?
yes,
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now go measure with your nano if you have one. What is your name? (second time I ask) Op 20-7-2022 om 16:08 schreef Observer: I have found the most, mouthful fed examples on how to use a vna. |
Re: nanoVNA for Nerds
On Thu, Jul 14, 2022 at 07:56 PM, Ken wrote:
That's another good reason or feature of the Nano's price! If you blow it up (by transmitting into it), it probably won't break the bank. BUT if the transmitter blows up too, well then you'll wish you looked (and learned) before you jumped. -- Doug, K8RFT |
Re: High impedance antenna measurments
#applications
On 7/19/22 9:00 PM, Observer wrote:
Anyone has used the nano with an antenna bridge ( or noise bridge ?) to measure antenna impedances other than 50 ohms, like 300 ohms and up ?I don't think you want to use them together. The NanoVNA directly measures impedance vs frequency. Yes, the usual display is S11 referred to 50 ohms, but you can convert that to R and X (and, in fact, it will do that for you) No reason why it won't measure 300 ohms. |
Re: High impedance antenna measurments
#applications
On 7/20/22 2:13 AM, Ed G8FAX wrote:
Is there a performance specification for the nanoVNA?I don't know that there's published specifications - it's more "we built it, you use it, as found" There's a fair amount of lore - measurements people have made, etc. It's kind of different from buying a VNA from, say, Keysight where they have a published spec sheet, acceptance tests, etc. That is part of what makes the FieldFox cost 100x what the NanoVNA costs. Practically speaking, it puts out about 0 dBm, has about 60 dB dynamic range (sometimes as much as 80 dB), covers 50 kHz up to at least 900 MHz (some versions cover more), has 101,201, or 401 points in a sweep (depend on software version). |
Re: High impedance antenna measurments
#applications
On 20/07/2022 11:14, Arie Kleingeld PA3A wrote:
I've measured in the HF range only.Most interesting, Arie, thanks for posting. Judging by your plots, I'd say the 1-ohm to 470-ohms range is quite acceptable. More complex, though for someone wanting to measure antennas! 73, David GM8ARV -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv |
Re: High impedance antenna measurments
#applications
I've measured in the HF range only.
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Low and high impedances, testing with resistors. The results are in the following documents: 73, Arie Op 20-7-2022 om 11:24 schreef David J Taylor via groups.io: On 20/07/2022 10:19, alex wrote:In my possible dumb imagination I would use a 10 or 20 dB attenuator to avoid mismatch on the NanoVNA side. Then measure the impedance. Then I would make an a-symmetrical attenuator from 50 to that first guess en measure again. This would only require some resistors. Or am I wrong?I think that would make high/low measurements much less accurate! |
Re: High impedance antenna measurments
#applications
On 20/07/2022 10:19, alex wrote:
In my possible dumb imagination I would use a 10 or 20 dB attenuator to avoid mismatch on the NanoVNA side. Then measure the impedance. Then I would make an a-symmetrical attenuator from 50 to that first guess en measure again. This would only require some resistors. Or am I wrong?I think that would make high/low measurements much less accurate! To the OP: As a suggestion, anything more than, say, 5 times from the nominal 50 ohms will be subject to increasing inaccuracy. Say 10 - 250 ohms you might be OK? Perhaps someone might like to confirm this? Perhaps better if you use a 4:1 transformer - the appropriate way round? 73, David GM8ARV -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv |
Re: High impedance antenna measurments
#applications
In my possible dumb imagination I would use a 10 or 20 dB attenuator to avoid mismatch on the NanoVNA side. Then measure the impedance. Then I would make an a-symmetrical attenuator from 50 to that first guess en measure again. This would only require some resistors. Or am I wrong?
73 Alex. PE1EVX |
Re: High impedance antenna measurments
#applications
Is there a performance specification for the nanoVNA?
Particularly interested in V4.2 HW version as I have one Kind regards Ed G8FAX |
Re: High impedance antenna measurments
#applications
You won't need it. The nano measures it all.
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What's your name? Op 20-7-2022 om 10:34 schreef Observer: yep, I am experimenting with hf antennas, with unknown, or predicted high z or very low z |
Re: High impedance antenna measurments
#applications
yep, I am experimenting with hf antennas, with unknown, or predicted high z or very low z
|
Re: High impedance antenna measurments
#applications
Are you going to use one?
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Op 20-7-2022 om 06:00 schreef Observer: Anyone has used the nano with an antenna bridge ( or noise bridge ?) to measure antenna impedances other than 50 ohms, like 300 ohms and up ? |
High impedance antenna measurments
#applications
Anyone has used the nano with an antenna bridge ( or noise bridge ?) to measure antenna impedances other than 50 ohms, like 300 ohms and up ?
|
Re: Low pass filter
F1AMM
Concerning your filter, note that:
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nanoVNA makes its measurements with an internal 50 ? impedance generator. When you use this filter behind a PA, fortunately, its internal impedance is not 50 ?; otherwise the yield would be catastrophic. This difference greatly changes the transfer function of the filter. On the other hand, when you measure the S11 at the input of the filter, the latter being charged at the output by 50 ?, the measurement is correct. -- F1AMM Fran?ois -----Message d'origine-----De la part de Stan Gammons Envoy¨¦ : mercredi 20 juillet 2022 03:28 |
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