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Re: Operating Close to 7.3G and some NOOB RF/SpecAn Questions

 

The power level of a CW signal should remain the same with RBW changes.? Modulated signals (which are noise-like) and noise signals (like the baseline noise level) will change with RBW changes.
73, Don N2VGU
Re: Operating Close to 7.3G and some NOOB RF/SpecAn Questions

 

Thanks Guys,
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I’ve been using one of these:
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It seems to be doing a good job at backing everything else off.
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Is there a better antenna for this work? I ran a crude test with a number of antennas including an Omni from the video link manufacturer and this seemed to be the most sensitive.?
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Re: Operating Close to 7.3G and some NOOB RF/SpecAn Questions

 

Make sure you have a high pass or band pass filter in line when measuring with an antenna like this at those frequencies.I normally use Mini circuits high pass filters they are good enough to suppress anything from the lower range to bleed through.
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John
Re: Operating Close to 7.3G and some NOOB RF/SpecAn Questions

 

On Sat, Apr 12, 2025 at 12:10 AM, Ash McKenzie wrote:
There seems to be random noise from the 7.3g mark onwards, is it case where the unit can only be used in Ultra under 7.3 and then must recalibrated to Harmonic Mode 7.3 and above ? there arent any option for ai cross over range are there ?
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Need to look into this?
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Second question (RF/SpecAn), I have been learning about the DANL change that occurs when changing the RBW my question, should power level dbm remain consistent when changing RBW, is it only the accuracy & DANL ?
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Yes
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--
Designer of the tinySA
For more info go to

Operating Close to 7.3G and some NOOB RF/SpecAn Questions

 

Thanks to Erik and All devs for a wonderful device, also thanks to Ian for his great python work (the app)
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Just wondering about expected behavior of the 407 when working close to 7.3g, I'm doing some environmental monitoring of Video Links 7.1, 7.285,
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There seems to be random noise from the 7.3g mark onwards, is it case where the unit can only be used in Ultra under 7.3 and then must recalibrated to Harmonic Mode 7.3 and above ? there arent any option for a cross over range are there ?
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Second question (RF/SpecAn), I have been learning about the DANL change that occurs when changing the RBW my question, should power level dbm remain consistent when changing RBW, is it only the accuracy & DANL ?
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Thanks
Ash?
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Re: Determining antenna factor

 

G in AF formula is the Linear Gain of the antenna
Re: Wideband antenna

 

I will first try with PCTEL OP451 omni wb antenna and will also take into consideration at least a log antenna.
Already calculated all required info, specially AF (needed as input into TinySA - TRACE/CALC/TABLE TRACE)
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Re: Wideband antenna

 

If you are interested in knowing the field strength at your location, you only need to consider the equipment at your end. It makes no difference how the field happened to get there. If you are designing a communication system link budget then you would need to consider both ends.?

I have one of the WA5VJB antennas and he does a nice job, if it matches your frequency range of interest.
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Good luck!
Craig
Re: Wideband antenna

 

So, I asked ChatGPT and gave me this answer:
Is "shortcut formula" good enough for my use-case?
Re: Auto Save Issues

 

Thank you. I think I found the line in the code to edit.?
Thanks again.?
Re: Zelftest 3: signal level critical

 

Search ESD in the Messages section for more information
Re: Auto Save Issues

 

The source of the tinySA is on github.
You can change this value in the code and build a new FW
--
Designer of the tinySA
For more info go to

Re: Zelftest 3: signal level critical

 

The selftest shows that U22 needs to be replaced, no problem
But I see D4 at the RF input. Is this a real diode? There is no recognizable marking on the part.
Because if so this tests blown also. What type of diode should it be replaced with?
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Regards, Johan
Re: Wideband antenna

 

Thank you all for recommending affordable log periodic antennas!
The PCTEL OP451 (450 MHz – 6 GHz, vertical polarization) I found is around $90 (used, not new).
Is it worth that price tag?
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As I mentioned before, my use-case is (trying) to measure the field strength, but also see the spectrum (therefore SA).
The math to go to V/m or W/m2 goes through antenna aperture, distance, frequency, etc.
But I don't know if I need to know mine as a receiver or the emitter's antenna aperture?
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I thought (as a newbie) that if I can measure the amount of power (measured with TinySA) arriving at my probe/antenna and knowing the antenna surface I can do some math from there...
But I also think that not all antenna surface is involved in "coupling" with certain frequencies and I don't know if this is the right way to go...
Should I open a new topic on the differences between measuring E-field (e.g. Narda) and scanning the signals power levels (dBm or Watts) with TinySA + math?
Thank you all for guiding me in this
Re: Auto Save Issues

 

Hi Erik,
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I have tried to all options that I know of to get the TinySA Ultra ZS405 to auto save traces as fast as possible. The best I can get is every 30 seconds. There seems to be a hard cutoff in the code that doesn't allow the autosave to work any faster. Would an old firmware not have this issue and allow continuous autosaving? If I can get the autosave function to work every 3-5 seconds (faster would be better) I would like to buy 10 or so tinySA's for a fun project. If you have any knowledge of how to make the autosave function faster your input would be greatly appreciated.
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Thanks again. You developed a very interesting device.?
James
Re: Wideband antenna

 

WA5VJB makes several log periodics:


Note, Kent spent a LOT of time developing these antennas. They are made for a specific dielectric constant for FR4/G10. The dielectric constant for FR4 and G10 on the market varies widely and wildly. Kent ordered a large quantity of the pc board material so it would have the same dielectric constant and probably last him a lifetime. Others have copied his designs but made them on pc material with a different dielectric constant. They will NOT perform as his designs do. A lot of these imitation boards are available on Amazon and eBay. I would buy the ones directly from Kent.

Zack W9SZ


On Thu, Apr 10, 2025 at 9:50?AM W0LEV via <davearea51a=[email protected]> wrote:
There are also available printed LPs with included antenna factors already documented.? And.... considerably less $$ than the referenced Amazon units.? Just do a www search.

Dave - W?LEV

Virus-free.

On Thu, Apr 10, 2025 at 12:22?PM Donald S Brant Jr via <dsbrantjr=[email protected]> wrote:
I use this PC board-based log-periodic antenna for EMI searching: ?
To be reasonably useful I put a preamp right on the antenna connector. ?
The internal battery makes it very convenient.
Best regards, Don Brant



--
Dave - W?LEV
Re: Wideband antenna

 

There are also available printed LPs with included antenna factors already documented.? And.... considerably less $$ than the referenced Amazon units.? Just do a www search.

Dave - W?LEV

Virus-free.


On Thu, Apr 10, 2025 at 12:22?PM Donald S Brant Jr via <dsbrantjr=[email protected]> wrote:
I use this PC board-based log-periodic antenna for EMI searching: ?
To be reasonably useful I put a preamp right on the antenna connector. ?
The internal battery makes it very convenient.
Best regards, Don Brant



--
Dave - W?LEV
Re: Wideband antenna

 

I use this PC board-based log-periodic antenna for EMI searching: ?
To be reasonably useful I put a preamp right on the antenna connector. ?
The internal battery makes it very convenient.
Best regards, Don Brant
Re: Wideband antenna

 

My goal is to have a "good-enough" and cost-effective antenna for the 600 MHz - 6 GHz spectrum
As a probe for scanning how the spectrum is occupied and at what power levels are the signals.
I think I need an Isotropic/omnidirectional probe, as I am not really interested in "finding" the source.
I don't know how much the Schwartzbeck log periodic antenna cost, in what price range it sits?
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Regarding TinySA Ultra, with any of the mentioned antenna, I must use TRACE > CALC > TABLE TRACE (and save it to SD)?
And create a trace containing a 8 point linear interpolation of the AF versus frequency from the antenna gain graph
I can calculate/estimate AF from the gain graph here: https://www.everythingrf.com/rf-calculators/antenna-factor-calculator

Is it ok(ish) to "approximate" the 20 points graph to only 8 points in the TABLE TRACE?

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Also, looking at the Narda SRM-3006 probe (E Field Probe 27MHz - 3GHz), it could also have vertical polarization like my above-mentioned PCTEL OP451?
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Is there something I must know about the (big?) differences between measuring E-field (Narda) and scanning the signals power levels (dBm or Watts)?
At the moment I have this as a starting point:
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source: 2
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And, as I only receive/measure "in the air" and don't know the emitting antenna's aperture, how can I go from there?
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Thank you!
Re: Determining antenna factor

 

Hi Charlie,

Can I assume G is dBi not dBd
?Cheers Dave


On Thu, 10 Apr 2025 at 06:58, W0LEV via <davearea51a=[email protected]> wrote:
I presume G is gain.? Is that in dB or the numerical ratio before the 10log[ratio]?

Dave - W?LEV

On Tue, Feb 4, 2025 at 2:38?PM W5CDT via <charlie.texas=[email protected]> wrote:
A handy formula…..plot your antenna gain vs. frequency and convert to AF vs. frequency
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-Charlie
?W5CDT
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Dave - W?LEV
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