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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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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

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

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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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

That filter is the same I am using looking at our 6GHz STL, it works well.

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John

Thanks for this Don,

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so FM, nFM and AM will all have their power level impacted by a change to RBW, is there any formula for this ? Or is it a fairly minimal impact??

Or it is more to do with the “Noise Like” nature of the signal, a CW is very uniform where these other types are more chaotic ??

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It has to do with whether the IF bandwidth is sufficient to capture all of the spectral components, and also with the fact that the SA is calibrated to respond correctly to a CW signal, not power, although newer SAs have an RMS detector function.?

There is an additional adjustment which accounts for the different way in which the analyzer responds to noise(like) signals than to CW.

Here is a Keysight app note which goes into more detail: ?

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There is also a need to compensate for CW signals in the presence of noise. When the signal is 10dB above the noise there is an approximate 0.4dB error due to the noise power being added to the CW signal; when the signal is equal to the noise there is a 3dB error.? I have a spreadsheet which takes as inputs the noise level and CW signal level and makes the correction as well as an article by Morris Engleson (who authored a very excellent book on spectrum analysis) explaining the calculation and its background.? Newer analyzers also have a similar noise correction routine.

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Best regards, Don

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The tinySA can do channel power measurements. You can use a channel wide enough to capture all the spectral components and it will give you the total power.

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Designer of the tinySA
For more info go to