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The input power of the fundamental should be as low as possible to avoid the tinySA generating internal harmonics. But the fundamental should also be so strong the harmonics do not disappear into the noise.
In this example:?
you see that keeping the fundamental just below -25dBm (with 0dB attenuation, increase attenuation if you increase the level of the fundamental) gives the largest measurement range of observing harmonics.
The first example in this video:?
shows the measurement of a signal with harmonics where the fundamental is at -25dBm
A practical example of measuring the harmonics from an actual transmitter can be found here:?

On Wed, Sep 16, 2020 at 06:28 AM, Scott hunter wrote:

"with an external ittenuator what is the maximum input the spectrum annalyzer would handle 1dbm or 2 dbm or even lower any chance could u give me a accurate reading"

? ?Scott that's kind of a loaded question because it depends on the level of the signal you are measuring and the attenuator you are using.? See this page for maximum input ratings for both the LOW and HIGH inputs,??.? For best measurement accuracy Erik recommends that you choose an external attenuator that reduces your signal to -20dBm on the low port and -30dBm on the high port.? Use the LEVEL->EXTERNAL AMP setting to correct for the external attenuator.

"..also did u design this spectrum annalyzer?thanks for replying .."

? Erik is the proud designer of the tinySA and knows it backwards and forward.? He also maintains the firmware and the tinySA.exe software.? That is why he is able to respond so quickly to user input.? The tinySA is a result of almost a year of design work that originally started on the? Amatuer Radio Homebrew Test Equipment group.

- Herb

On Wed, Sep 16, 2020 at 07:14 AM, Karl Heinz Kremer - K5KHK wrote:

It lists the maximum input power as 10dBm - anything more and you will likely fry it. For a "good" reading, I try to keep the input signal below -30dBm

This is with 0dB internal attenuation. If you increase attenuation these numbers can go up with the attenuation but do not fry the internal attenuator.?
With 30dB attenuation the tinySA will survive a +30dBm signal for a couple of seconds.?
With attenuation on automatic you are perfectly safe and you can expect good measurements of you stay below +5dBm
But to give the attenuation some spare I suggest to always stay below 0dBm at the input. This will allow you to use the internal attenuation most effective

On Wed, Sep 16, 2020 at 08:46 AM, Scott hunter wrote:

..is it minus 10 dbm or a normal 10 dbm which is 10 milli watts thanks

+10dBm

On Thu, Sep 17, 2020 at 12:43 PM, Scott wrote:

s 2.5 milli watts too high of a input to measure harmonics on the low input on the tiny sa?

That is about +3dBm. If you set the internal attenuator to 30dB you should be ok for harmonics measurement

On Sat, Sep 19, 2020 at 03:30 PM, Scott wrote:

hello there cant seem to beable to calobrate the high input it shows up red on the display.. the low input is calobrated fine that shows in white..have i done something wrong? if you could reply that be great thanks...

Scott,
? If you have an accurate external generator the procedure is straight forward.

? 1.? Connect the generator to the high port using a frequency from 240-960M and at a level that does not over drive the port (i.e. -30dBm).
? 2.? Center the signal and use a span of about 10MHz for good level accuracy.
? 3.? Go to CONFIG->EXPERT CONFIG->ACTUAL POWER and enter the generator output level (i.e. -30dBm).
? 4.? In Step 2 above if the tinySA measured? -28.4dBm, as an example, then after Step 3 it should now be reading -30dBm and the display level values should be white instead of red (this doesn't happen immediately so you may have to wait a few seconds).
? 5.? High port calibration is complete.

? If you don't have an accurate signal generator, than you can use the procedure that Erik demonstrated to calibrate the high port.? He took advantage of the fact that the high and low port have a frequency overlap in in the 240 - 350MHz range.? You can accurately measure a signal within that range using the low port and then use that value as a transfer standard for the same signal measured on the high port in Step 3 above.

? From a serial terminal if you enter 'leveloffset'? before the high port is calibrated the tinySA should return 'leveloffset high 100'.? The '100' indicates no calibration has been performed.? In the example calibration in steps 1-4 above, if the tinySA measured -28.4dBm before calibration and -30dBm after 'ACTUAL POWER' calibration, then the 'leveloffset' command should now return 'leveloffset high -1.6'.

?In the future, again using the above steps as an example, to perform a high port calibration you could just enter the following from a serial terminal:
? 1. leveloffset high -1.6
? 2. saveconfig

? Hope that helps.

? - Herb

Just checking… did you realise that you have to calibrate against a known signal for the high input? It’s not done as part of the high-low connection calibration.?