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Dave, A man with two watches dies not understand measurement theory. The one watch guy has error too..the two watch guy measures it partly… Vince and I have discussed this.. Frank K4FMH

Looks like there can be some compression above -1dBm. The overall linearity is spec'd at +/- 2dB if you avoid this "gotcha" https://www.tinysa.org/wiki/pmwiki.php?n=Main.Specification Back down the

Well RATS!!? ?I knew the itty bitty geared DC motors I was using were pretty small. *Apparently I stripped a portion of a gear this afternoon.* It works find down to about 25 degrees and won't go

Thank you Evan. Can it lower the carrier peak and cause false increase of the spurs (vs the carrier)? I'd be glad to find my measurements incorrect. 73, Wojtek SP5DAA

Jody, others aren't reporting quite the same thing. You are pointing to a delay in the T/R circuitry, and indeed there was one in the sBitx, as well as a sampling issue throughout. However, it

*RE;? Why do some people have a problem with the zBITX CW Mode and others do not?* I tested with a Straight Key.? ?I can offer the following observations and opinions: - Send Fast (20-25 WPM) and

I am not getting good results with the AGC supplied by AmateruRarioKits.? I am unsure if it is a bad board (it does not have the multi-turn potentiometers shown in the documentation) or if it is the

Wojtek, From the TinySA Ultra wiki: * For best measurements keep input power below -25dBm I always ensure that the peak displayed is below -25dBm.? With either my Basic or Ultra, I get different

So one hypothesis is that HFSignals got a bad batch of ms5351's, where some of them perform below spec in terms of clock crosstalk. ?But some (Ashhar's) are Ok. If this turns out to be the situation,

A man with a watch knows what time it is, a man with two watches is never sure... @VE6LK @HRWB -- Regards, Dave, N1AI

I have tested my zBitx in CW mode with DRIVE=100 with 50 Ohm 40 dB attenuator and tinySA, on all bands. Sorry, I took the pictures with a mobile, so the quality is poor. Below are the results. 10

Oddly enough, I don't show this using the zBitx on 40m with the tinySA Ultra, same span. This is the first good thing I'm able to report about this radio.

Sam, Wolfgang, I would lift off the front panel (un-snugging the four screws might be enough) to see if it relieves pressure on the screen itself and try again. When I tried with mine it sat forever

So what is different about Ashhar’s unit, since he’s not seeing it? Different manufacturer of the chip? Different bypassing? Different loading?

If intermodulation is between the 40 MHz clock and transmit clock, a quick test might be to turn off Si5351 clk1 during transmit (re-insert 40 MHz farther down the signal chain from an external clock

I did some additional measurements and I am now pretty sure, that the *root cause for the spurs is intermodulation between the 40MHz IF signal @ CLK1 and harmonics of the transmit oscillator signal

I have yet measured the output voltage (after the 40 dB attenuator). Below are the results. Indeed, one can see a 2 MHz amplitude modulation. That's not an aliasing artifact. Below there is a

The calibration screen does come up - for less than 2 seconds. Not enough time to calibrate. What next? Thanks, AC4OW, Sam Hanie samhanie@... [email protected]> wrote:

I don't know where R70 is on the PCB, or how accessible it might be. Can Ashhar have someone back at the factory swap out R70 with a clock buffer and see if that reduces spurs? - Ron

Frank, my measurement setup has been described already in my FIRST posting on this topic: " Measurement with a TinySA Ultra connected via 50dB (20dB + 30dB) attenuators. Adding another 30dB of