#1088 Spectrum Analyzer with Tracking Generator

Episode 1088
Sent into the channel for review by JunShunTong on Amazon

[johnwest]

A spectrum analyzer that starts at 35 MHz is like a flashlight that only works during the day.

[solarflare]

Very useful tool but starting at 35Mhz limits its use for the HAM's short wave bands or intermediate frequencies in the KHz ranges. I would have bought one of these if the lowest frequency was starting at 10-50khz ... There is the "Ultra" out there but without a TG... Great video as all your other videos are! Tnx for taking the time to share these reviews...

[LutzSchafer]

The "mysterious" dip in the response to a single tone is known to this and other similar cheap devices. The dip occurs when the displayed mixed IF becomes zero or DC, which happens when the tone and the sweep frequency become equal during the sweep with the seond sweep generator on board. This is because towards the very low frequency mixing product (including DC) will not make through the detection highpass. Therefore calling this a spectrum analyzer seems a slightly false advertisement. Due to the simple design there is no way to get rid of it, which why real spectrum analyzers have multiple mixers and IF's. And yeah the resolution bandwidth is another story. The tracking generator outputs a square wave which has lots of harmonics, which do not interfere with the analyzer part.

On second thought, I believe this could be corrected in software using a simple inverse (Wiener) filter together with the characteristics of the highpass in the detection path. Only the exact zero (DC) case would cause a singularity and needs interpolation which is simple. An inverse filter in hardware is a bit more challenging. I think there were some notes out on using steeper higher order LC filters, but they only make the notch narrower.

[archerkee]

thank you for your videos, I have learned a lot from them. Are you planning to review rfexplorer? and perhaps something on how it works together with the rf signal generator.

[clems]

i hope its more dependable than the NANO-VNA !

[richsjt]

As in episode 1085, did you calibrate of camera?

[__--JY-Moe--__]

now I can tune my antenna's, on the cheap! story of my life...the mountains R so challenging 4 uhf com's...but then again, mountains R hard 2 move! right...

[LazyTurtle]

Can you read the name of U6 and U9 parts or they have wiped them? I'd like to check their datasheet if possible.

[gixerags]

for HF 27meg users, is there a reason they start at 35mhz than say 25mhz?
thanks in advance

[JimAndyAllyn]

Looks like they are asking $268.99 for it on Amazon. Not worth it, get one of the NanoVNA models.

[therearelights]

Wonder how this directly compares with the TinySA. Would be interesting to see that side by side.