Wednesday, August 31, 2022

A new addition to the test bench


A brand new Rigol spectrum analyzer found its way to my shack a couple days ago and I'm looking forward to using it, and other equipment, to make various tests on QRP (mostly) rigs that would pass under the radar of the ARRL lab.

I previously made those measurements using a combination of my own gear and that at my old work QTH, most recently on the Penntek TR-35 here. Or with the IC-705 here and here. And with the FT-891 (not online).

In both cases (IC-705, FT-891), I was pleased to find my MDS results within 1 or 2 dB of those measured by Rob Sherwood.

Until now, I've lacked my own spectrum analyzer and 2-tone test generator. A 2-TTG is on the way and the new Rigol is the DSA-815-TG with tracking generator. The Rigol's display of my FT-891's spectra is identical to the traces obtained with my work QTH's Rohde & Schwarz.

The main difference (at HF/VHF anyway) between the Rigol and the R&S is that the Rigol is slower to make a scan when resolution BW is at the finer settings - settings not necessary for making plots of harmonic content at HF frequencies.




  1. Hi John, I'm wondering what happened to the Siglent SA you had?

  2. Good morning Pete,

    Yes, I remember talking about the Siglent with you. You had recommended a person at Siglent for me to speak with regarding a difference in its trace compared to a SA at my work QTH when looking at a radar's output pulse. I contacted the man (John, I think) and we exchanged several emails & jpgs of the display. I tried everything he said yet could not get the Siglent to show the proper, known trace of the radar. He offered me a refund for the SA and I took it.

    Now every time I build a kit, I wonder how its output looks. I have a tinySA, but that is more of a gadget than a proper SA, although the sig-gen function of it is extremely accurate up to 100 MHz or so. So I bought the Rigol. I can compare it to plots I made at my work QTH of the IC-705 and FT-891 - spot on, so I'm happy with it and confident of its accuracy.


  3. Too bad the Siglent didn't work out. I've been quite happy with mine and there are now 5 among our hb friends. Having said that it's interesting that the Rigol is picking up where the Siglent did not. I wonderwhat it is about the 2 SA's that made the difference?

  4. Maybe it's possible that I got a bad unit from Siglent? I wonder about that still. It was a high-QRM environment - meausuring a 4 megawatt radar (our most powerful one), while it was radiating on two frequencies simultaneously, via an attenuated tap on a coupler. Maybe stray RF was influencing the reading. Also, of all the radar sites in SE Texas that we handled, this was the only one with a Rohde & Schwarz SA - all other sites had Agilents, which are much lower priced. Maybe only the R&S had the shielding necessary for this radar's emissions (in the building, not at the antenna).

    Man, what I'd give to have the R&S, Siglent and Rigol - and a radar site to compare them in!