(tr)uSDX Forum

Group,

I believe in the US the FCC requires that none of the first 3 harmonics are less than -30db down. I put my TinySA to work and all the bands except the 80 meter band looked legal, the 60m was marginal


Here are the images:

Here are the other two band harmonic spectrums

Dear Nameless OM AC9UV,

To my knowledge, the FCC requirements are -43dB minimum harmonic suppression.

In order to fulfil that, I´d suggest
a) to update your tiny SA´s firmware. It´s from STone-Age, it seems and
b) tune your Filters according to my Video (especially regarding second harmonic notch) to fulfil FCC requirements:
https://www.youtube.com/watch?v=qN7hHsvcNMM&t

P.S: My measurements shown here: https://dl2man.de/2-trusdx-assembly/


73 Manuel; DL2MAN

How are you making the measurements? You need to use an attenuator and dummy load to get accurate harmonic measurements. If I have some spare time this evening I will try both of mine, but I seem to remember when I first got them I tested them and they met or exceeded FCC requirements on all bands. My uBitx V6 took some work though.

I used a dummy load and the TinySA has built in attenuation.

I'll look at the other information about calibration and setup.

--AC9UV

FYI John Putnam AC9UV you can look up my info on QRZ

73

I used 70db attenuation to measure mine
In the USA I think the mean power of any spurious transmission must be at least 43 db below the mean power of the fundamental transmission if working below 30 megahertz, currently. Used to be less strict and some older equipment is grandfathered.

I think mine are all legal. Have only checked at one point on each band and not sure if this was before or after tweeking the harmonic torroids.