I have run in to the same issue with the 1.2.00-199 FW. I'll have to try removing the SD card. On mine, I can plug in a cable in to the C USB jack and it comes alive !?! The other end of the USB cable is unterminated. Not sure what the heck is going on there, I but I got it to work.
I've been using TimeLab. Attached is a plot of my Lucent RFTG-u versus a pair of 10 MHz OCXO's I was looking at for use in the field. The Toyocom That N2CEI sent me wins by a bit...
Mike
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On 2/21/2023 12:35 PM, Roger Need via groups.io wrote:
First impressions
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I loaded FW version 1.2.00-199 into my -H4 today and took it for a test drive.
It would only boot occasionally and screen stayed dark most on most tries. I recall this problem with old versions of the -H4 firmware and it had to do with the SD card being installed. So I removed the SD card and it boots every time. I have not had any boot problems with -H4 firmware in any version released in the last year or so.
I connected a Bodnar GPSDO to a 10 MHz. BG7TL 10 MHz. BPF filter and a 12 dB attenuator and used that as the input to the A input. After letting the -H4 TCXO warm up for a while I nulled the frequency and that worked well.
The Bodnar was also connected to a Siglent 2122X AWG as an external reference. Signal output configured for 10 MHz. and input to Channel B. Frequency difference was in the tens of microHertz which I thought was excellent for this setup. Adjusting the Siglent frequency to port B by 10 milliHertz steps gave accurate differential readouts.
Next I set the second channel of the Siglent to 10 MHz. and used that as the frequency reference. Nulled the phase between the two and then changed the phase in 1 degree steps. Measurement was very close (can't remember error).
Summary: - the tinyPFA is impressive as a measurement device. It is nice to be able to just load the FW to do measurements when needed and then reload -H4 firmware when finished. I use the NanoVNA app for FW updates and that is an easy to use application.
Roger
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73,
Mike, N1JEZ
"A closed mouth gathers no feet"
Mike N1JEZ
