Spectrum Analysis of bands

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AC9UV
 

Posts: 8
Joined: 19 May 2022, 22:09

Spectrum Analysis of bands

Post by AC9UV »

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:
Attachments
SA40.jpg
SA40.jpg (241.26 KiB) Viewed 1448 times
SA30.jpg
SA30.jpg (221.47 KiB) Viewed 1448 times
SA20.jpg
SA20.jpg (197.04 KiB) Viewed 1448 times
AC9UV
 

Posts: 8
Joined: 19 May 2022, 22:09

Re: Spectrum Analysis of bands

Post by AC9UV »

Here are the other two band harmonic spectrums
Attachments
SA80.jpg
SA80.jpg (215.19 KiB) Viewed 1447 times
SA60.jpg
SA60.jpg (206.91 KiB) Viewed 1447 times
DL2MAN
 

Posts: 706
Joined: 30 Dec 2021, 19:18
Contact:

Re: Spectrum Analysis of bands

Post by DL2MAN »

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
AC9YY
 

Posts: 133
Joined: 21 Mar 2022, 00:04
Location: Illinois, USA

Re: Spectrum Analysis of bands

Post by AC9YY »

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.
AC9UV
 

Posts: 8
Joined: 19 May 2022, 22:09

Re: Spectrum Analysis of bands

Post by AC9UV »

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

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

--AC9UV
AC9UV
 

Posts: 8
Joined: 19 May 2022, 22:09

Re: Spectrum Analysis of bands

Post by AC9UV »

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

73
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: Spectrum Analysis of bands

Post by Ohwenzelph »

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.
Attachments
-50db tap then 20db more atten
-50db tap then 20db more atten
9FDB5CDA-0F62-49F0-8082-350B6B427662.jpeg (84.5 KiB) Viewed 1407 times
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: Spectrum Analysis of bands

Post by Ohwenzelph »

80
80
177273FC-75A9-4E79-A3F0-23D0B00A0DEA.jpeg (115.17 KiB) Viewed 1404 times
60
60
6DD4B89E-74CB-4334-8186-13E26726204A.jpeg (112.56 KiB) Viewed 1404 times
40
40
7115BE5E-079A-483A-BBA0-C1D2AE8DC6C3.jpeg (117.04 KiB) Viewed 1404 times
Ohwenzelph
 

Posts: 207
Joined: 01 Jan 2022, 03:47

Re: Spectrum Analysis of bands

Post by Ohwenzelph »

30
30
678B834B-9E6D-4775-AD53-255DD6EE5AC9.jpeg (124.96 KiB) Viewed 1404 times
20
20
D9A71A1B-062E-49A2-B885-B23080F671AB.jpeg (88.54 KiB) Viewed 1404 times
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.
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