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Sticky What to do when a selftest fails

 

Test 13 is the attenuator test
Search the wiki for the detailed attenuator test (linearity)
--
Designer of the tinySA
For more info go to

 

Changed out U14 LNA and Tests 10 and 14 are now good - only Test 13 fails.
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Is this Test 13 failure from U22 being bad??
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I also bought a few of them when I got the LNA chips
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Thanks
-Paul
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On Fri, Jan 17, 2025 at 08:19 PM, Hugen wrote:

U14 LNA is damaged.
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On Mon, Jan 13, 2025 at 02:12 PM, PT wrote:
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Hide quoted text

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Purchased on Amazon SeeSii store
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Came with v1.4-185. Updated firmware.
Fails using both 189 and newest 193
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Failed tests are 10, 13 and 14
?
?
?
Did a Config Reset
30M Attenuator test
 

Herb thanks for the advice. I'm ordering spares and will replace the switch first
Bob E - thanks I'll be getting a DC block for sure
Erik thanks I'll will be using a attenuator and DC block from now on. Many thanks for making this wonderful
?? test equipment available
Bob G I was using it as a signal generator at the time. I did exactly that, connected directly to scope and then
?? attached the 50ohm terminator to check the level. Thanks for your input
Regards, Reggie
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The input capacitor is around 1uF SMT. Hard to get these in high voltage.
Mind you, I would like to see a slightly higher voltage cap used. But I believe the main problem is the breakdown voltage of the protection diodes.
Erik may like to comment.
Regards...Bob VK2ZRE

On 20/02/2025 3:10 am, Terry Perdue via groups.io wrote:
? That is why a DC Block is such an important part of your test kit. It is just a capacitor in series with the centre conductor in an SMA-M to SMA-F adaptor.
Make sure it has a DC rating of at least 100V, preferably 200V. Many of the units on Ebay, etc are only rated at ~20V DC isolation.
HTH Someone...Bob VK2ZRE
With a higher voltage coupling cap, isn’t damage still likely due to the voltage spike as it is connected to a >5V source? I’m sure Erik would have used a higher voltage cap if that weren’t the case.
 

No DC on the input to the counter.? Not sure about input cap, I replaced the AS179-92 LF? and didn't go any further. It worked after switch replacement.


On Wed, Feb 19, 2025 at 2:14 PM, Terry Perdue via groups.io
<K8tp@...> wrote:
Does the counter show any DC on its input, and is the tinySA’s input cap now shorted?

>? I had mine at what I think is maximum output (-18 dbm) for 45 minutes feeding my scope without a probe and then I tee'd in a 50 ohm input frequency counter and that killed the AS179-92LF input switch. It took a few seconds, I was watching the scope and the signal decayed within 5 seconds of hooking up the counter.
> Bob
>






 

Does the counter show any DC on its input, and is the tinySA’s input cap now shorted?

I had mine at what I think is maximum output (-18 dbm) for 45 minutes feeding my scope without a probe and then I tee'd in a 50 ohm input frequency counter and that killed the AS179-92LF input switch. It took a few seconds, I was watching the scope and the signal decayed within 5 seconds of hooking up the counter.
Bob
 

Reggie,
?? How were you using it at time of failure??
?I had mine at what I think is maximum output (-18 dbm) for 45 minutes feeding my scope without a probe and then I tee'd in a 50 ohm input frequency counter and that killed the AS179-92LF input switch. It took a few seconds, I was watching the scope and the signal decayed within 5 seconds of hooking up the counter.
Bob


On Wednesday, February 19, 2025 at 08:10:33 AM PST, Terry Perdue via groups.io <k8tp@...> wrote:


> ? That is why a DC Block is such an important part of your test kit. It is just a capacitor in series with the centre conductor in an SMA-M to SMA-F adaptor.
> Make sure it has a DC rating of at least 100V, preferably 200V. Many of the units on Ebay, etc are only rated at ~20V DC isolation.
> HTH Someone...Bob VK2ZRE

With a higher voltage coupling cap, isn’t damage still likely due to the voltage spike as it is connected to a >5V source? I’m sure Erik would have used a higher voltage cap if that weren’t the case.
 

The tinySA input capacitor support inputs well below 100 kHz.
This implies large capacitance in very small form factor which is not available for high voltages with acceptable cost.
A separate DC block can be much larger and may not have to support low frequencies.
Make sure you put at least some attenuator between the DC block and the tinySA input to prevent DC buildup
--
Designer of the tinySA
For more info go to

 

? That is why a DC Block is such an important part of your test kit. It is just a capacitor in series with the centre conductor in an SMA-M to SMA-F adaptor.
Make sure it has a DC rating of at least 100V, preferably 200V. Many of the units on Ebay, etc are only rated at ~20V DC isolation.
HTH Someone...Bob VK2ZRE
With a higher voltage coupling cap, isn’t damage still likely due to the voltage spike as it is connected to a >5V source? I’m sure Erik would have used a higher voltage cap if that weren’t the case.
 

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That is why a DC Block is such an important part of your test kit. It is just a capacitor in series with the centre conductor in an SMA-M to SMA-F adaptor.
Make sure it has a DC rating of at least 100V, preferably 200V. Many of the units on Ebay, etc are only rated at ~20V DC isolation.
HTH Someone...Bob VK2ZRE

On 18/02/2025 10:51 pm, hwalker via groups.io wrote:

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:
?
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.
?
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.
?
Herb
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On Tue, Feb 18, 2025 at 10:31 PM, Reg Du Toit wrote:
Here are the results
?? The SA indicates a level of -75dBm at 30MHz
?? Switching on LNA the signal is gone completely
It does look as if the LNA is faulty but not to sure about the attenuator
I did a attenuator test and the green line was straight although also at a very low level
Maybe the input switch is also faulty
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? ?Assuming your unit was damaged while in the signal generator mode, the LNA was not in the signal path.? Either just the RF switch is faulty, as was the case for Bob, or also the attenuator.? I would purchase both and swap out the RF switch first.?
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I keep a spare set of these three components on hand to cover most repairs:
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- Input RF switch U22: XA17-G4K or AS179-92LF
- LNA U14: BGA2817
- Attenuator U38: PE4312C-Z
?
Herb
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Herb many thanks for your reply
?
Here are the results
?? The SA indicates a level of -75dBm at 30MHz
?? Switching on LNA the signal is gone completely
It does look as if the LNA is faulty but not to sure about the attenuator
I did a attenuator test and the green line was straight although also at a very low level
Maybe the input switch is also faulty
?
Bob many thanks for your input
?
Regards, Reg
?
?
?
 

i had exactly the same problem. Tiny Ultra SA failed in signal generator mode and stopped at selftest 3.? I replaced U22? the single pole double throw switch.?? AS179-92LF? and that cured the problem.
 

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
?
Tests 3 checks the 30 MHz CAL OUTPUT signal level.? If it is failing, try the following troubleshooting steps:
?
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.
?
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.??
?
I learned my lesson on a $5000 RF generator.? Thankfully the tinySA doesn't cost nearly as much.
?
Herb
?
 

Good day
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
Upgraded to v1.4 196
Checked cal output level on the SA ultra and its level is -72dBm, on scope unterminated is 20mV and terminated is 10mV
Inputted a 30MHz sine at 200mV and the SA ultra shows -50dBm
I will be very grateful if someone can please give me some advise and help fix my SA ultra
Many thanks, regards, Reggie
 

Hugen
Thanks so much for the reply.
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Can you confirm this would be a replacement for it
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I must have over-driven it.
 

U14 LNA is damaged.
?
On Mon, Jan 13, 2025 at 02:12 PM, PT wrote:

Purchased on Amazon SeeSii store
?
Came with v1.4-185. Updated firmware.
Fails using both 189 and newest 193
?
Failed tests are 10, 13 and 14
?
?
Did a Config Reset
30M Attenuator test
?
?
?
 

Can anyone help regarding posts 19061 and 19063 specifically the 3 failed self tests and what could be wrong with the unit?
Thanks
 

I've got an order pending for U22 from Digikey but if there is something else that might be borked on my unit I'll wait for more comments here, thanks.
 

The external gain is zero, but thank you.

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