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ZS-407 Spurious Signals

 

I just received my ZS-407 from R&L Electronics. I do frequency coordination for large events and the most common frequency range for wireless devices is in the 470 MHz to 608 MHz UHF TV band. I set the ZS-407 for a start frequency of 470 MHz and a stop frequency of 608 MHz. The RBW was initially set for auto. With no antenna on the 407 it was just showing a noise floor that was around -90 dBm. When I changed the RBW to 100 kHz, it displayed a spurious signal around 533.8 MHz. As I drilled down into this signal and reduced the RBW even lower, it turned out to be two very narrow bandwidth spikes at 533.725 MHz and 533.775 MHz. My older TinySA Ultra with the exact same settings does not display these signals. I also tuned my Icom IC-R30 to those two frequencies in CW mode and confirmed that no signals were received. Can anyone else see these “birdies” on their ZS-407 or is it just mine?
- Otto
 

On 22/01/2025 03:24, Otto Schellin via groups.io wrote:
I just received my ZS-407 from R&L Electronics. I do frequency coordination for
large events and the most common frequency range for wireless devices is in the
470 MHz to 608 MHz UHF TV band. I set the ZS-407 for a start frequency of 470
MHz and a stop frequency of 608 MHz. The RBW was initially set for auto. With no
antenna on the 407 it was just showing a noise floor that was around -90 dBm.
When I changed the RBW to 100 kHz, it displayed a spurious signal around 533.8
MHz. As I drilled down into this signal and reduced the RBW even lower, it
turned out to be two very narrow bandwidth spikes at 533.725 MHz and 533.775
MHz. My older TinySA Ultra with the exact same settings does not display these
signals. I also tuned my Icom IC-R30 to those two frequencies in CW mode and
confirmed that no signals were received. Can anyone else see these “birdies” on
their ZS-407 or is it just mine?
- Otto
_._,_._,_
Otto,

Here, with a span from 555.7 to 533.8 MHz, and a 200 Hz RBW, nothing seen. This
with Ultra enabled.

Cheers,
David
--
SatSignal Software - Quality software for you
Web:
Email: davidtaylor@...
BlueSky: @gm8arv.bsky.social, Twitter: @gm8arv
 

Otto,
Let me see what can be done to get rid of these
?
--
Designer of the tinySA
For more info go to

 

Thank you, Erik. Just to provide additional context, this is using FW 1.4.193, after two calibrations. The signals are there with LNA on or off and Ultra mode enabled or disabled. The signal levels - without an antenna and in a quiet RF environment - are about -74 dBm, about +52 dBm above my -126 dBm noise floor using 200 Hz RBW.?
FYI - many in my field are using the TinySA as a valuable tool for our work. I have had one (actually several) since they first came out and have developed software to control it for our specific needs. It is an amazing little device! Thank you for your efforts!
~ Otto
 

The worst spur is solved in my test setup, next I noticed some smaller spurs and now trying to get rid of these too
--
Designer of the tinySA
For more info go to

 

Yes, I did notice some additional spurs in that tuning range that were at lower levels. Thank you for looking at that!
~Otto
 

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Hi Otto, Dave and Eric

I took a quick look at my new ZS-407 last night after reading your posts. I too have the the spur described with a terminated input. 533.775 MHz at -70dbm. I didn’t drill down into the carrier, but might do so today before I upgrade firmware to the latest version.

Also it appears it might be intermittent with scan and RBW settings. We’ll see.

Everything else works great. Only thing I noticed was the noise floor across the spectrum measures slightly higher than my other two Ultra ZS-405 units by several db, but I believe an earlier description of the specs mentioned that.





On Jan 22, 2025, at 9:50 AM, Otto Schellin via groups.io <oschellin@...> wrote:

?
Yes, I did notice some additional spurs in that tuning range that were at lower levels. Thank you for looking at that!
~Otto
 

I hope to release a new FW that solves this problem later this week
--
Designer of the tinySA
For more info go to

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