On Tue, Feb 18, 2025 at 12:14 AM, Reg Du Toit wrote:
I bought my SA ultra from Zeenko Aliexpress
It was fine and passed all tests and calibration then
I have only used it as a signal generator and did not upgrade (v1.4 156)
While testing a transceiver I noticed the output level from the SA ultra was low so this is what I've done
Did a self test and it fails on #3 and goes no further
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Tests 3 checks the 30 MHz CAL OUTPUT signal level.? If it is failing, try the following troubleshooting steps:
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1.? Connect the CAL OUTPUT (top connector) to the RF INPUT (bottom connector).
2.? Select MODE:Calibration Output:30MHz
3.? Select Spectrum Analyzer
4.? You should see comb lines with the main carrier at 30 MHz @ ~-35.6 dBm.
5.? If you don't see any comb lines or comb lines with a carrier at 30 MHz well below -35.6 dBm then you either have a defective attenuator (U38:PE4312C-Z) or RF input switch (U22:AS179-92LF).
6.? Select LEVEL:LNA
7.? If you now see comb lines with the main carrier at 30 MHz @ ~-35.6 dBm then the RF input switch is working, and you have a defective attenuator.? Selecting LNA switches out the attenuator and switches in the low noise amplifier.
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When the tinySA Ultra is used as a signal generator it is subject to reverse voltage or turn on/turn off transients from the device it is connected to.? The only reverse voltage protection the tinySA Ultra has is its ESD protection diode.? That diode is not meant for overload protection.??
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I learned my lesson on a $5000 RF generator.? Thankfully the tinySA doesn't cost nearly as much.
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Herb
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