开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. Tinysa
  2. Topics

Put some transmit power into my Ultra

 

While doing some test on a remote repeater got distracted and ended up briefly putting some transmit power into the RF port of my Ultra while in generator mode. At first I had a small 30dB attenuator inline, which apparently went open circuit, but then before I realized the mistake and things did not add up anymore I removed the attenuator and once again did the same mistake this time straight into the RF port. Fortunately it was only very brief but still about 30W of UHF power (about 44dBm), so I assume that may have caused some damage. I did the self test by connecting the short jumper between the CAL and RF ports, and no errors came up, everything passed. Not sure that test also checks anything related to the generator as well. Also so far I have not tested the SA part, however it seems like the generator output is now somewhat off (low) at certain levels, but ok or very close on others. Assuming there is some sort of attenuator chip that is no longer working properly. Was wondering if anyone has gone through something similar and they where able to repair the unit by replacing any parts that where damaged, and would be helpful to know specifically what parts may need to be replaced. Thank you.
 

Search the wiki for the detailed attenuator test
Probably one section broken.
The attenuator can be replaced
--
Designer of the tinySA
For more info go to

 

I found the page, although it seems to originally relate to the original TinySA, not the ULTRA, as it still mentions Hi and Lo connectors.
https://tinysa.org/wiki/pmwiki.php?n=Main.CheckTheAttenuator
?
On the Ultra went to Mode and selected Calibration Output, and then selected 30MHz. Put jumper between CAL and RF terminals, went back to SA mode and activated the Linearity test as described on the wiki page and let it run. The green line came out straight and without any errors (see attached image). However noticed that first attenuator test starts at around 28dB, and ends at 1dB. Is that really the full range of the attenuator? Since the overload occurred while I was using about -100dBm of signal from the generator, wonder if that portion of the attenuator that was in use is also being covered with this test.
?
At the time of the overload incident with the RF power, I had the Ultra generator setup to test a repeater receiver on 462MHz with about -100dB output level, and with a small 2W external 30dB attenuator and properly set external gain to -30dB so indicated general signal level would be correct. Receiver threshold was opening at a signal level of -119.7dBm which was within the expected value. But once the transmit RF was accidentally activated the external attenuator had actually gone open circuit, which probably acted sort of a safety fuse but I only found out this afterwards. Then without realizing what had happened and getting wrong receiver test results, removed the external attenuator and connected the Ultra directly into the repeater and once again same RF came up, but this time went straight into the RF port.
?
Now that I had a chance, tested the Ultra generator output at both 150 and 450MHz and at levels between -30 and -90dBm against my service monitor and readings seem to agree withing 3-5dB depending on which frequency. So does this mean that if generator levels down to -90dBm look OK, the limit I am able to test this way, would that also mean it should also be OK at -120dBm? Wondering if it may still be possible there might be some additional attenuator stages that are used for signals lower than -100dB that may still be damaged?
?
Regarding tests on the SA part, compared the Ultra to my original TinySA and set both to monitor the same span of VHF frequencies each with its original antenna. Saw almost identical readings from expected signals withing that range. One repeater was being shown as -80.0dBm on the Tiny and -79.8dBm on the Ultra, so it looks like the SA part of the Ultra is also working as expected.
?
In closing, are there any other tests or calibration routines that you would recommend to run on the Ultra (aside from the SA self test which also did pass earlier) and that might apply in this scenario with the temporary overload of the RF port? Especially given the attenuator was being used at almost at the maximum range, and the linearity tests seem to be only testing between 28 and 1 dB attenuation.
?
Thank you.
?
?
?
?

ATT-CHECK_1200.jpg

 

On Sun, Jan 19, 2025 at 06:14 AM, Alex wrote:
On the Ultra went to Mode and selected Calibration Output, and then selected 30MHz. Put jumper between CAL and RF terminals, went back to SA mode and activated the Linearity test as described on the wiki page and let it run. The green line came out straight and without any errors (see attached image). However noticed that first attenuator test starts at around 28dB, and ends at 1dB. Is that really the full range of the attenuator? Since the overload occurred while I was using about -100dBm of signal from the generator, wonder if that portion of the attenuator that was in use is also being covered with this test.
?
Don't bother about the attenuator text. The test will cover the who attenuator range
?
?
At the time of the overload incident with the RF power, I had the Ultra generator setup to test a repeater receiver on 462MHz with about -100dB output level, and with a small 2W external 30dB attenuator and properly set external gain to -30dB so indicated general signal level would be correct. Receiver threshold was opening at a signal level of -119.7dBm which was within the expected value. But once the transmit RF was accidentally activated the external attenuator had actually gone open circuit, which probably acted sort of a safety fuse but I only found out this afterwards. Then without realizing what had happened and getting wrong receiver test results, removed the external attenuator and connected the Ultra directly into the repeater and once again same RF came up, but this time went straight into the RF port.
?
Now that I had a chance, tested the Ultra generator output at both 150 and 450MHz and at levels between -30 and -90dBm against my service monitor and readings seem to agree withing 3-5dB depending on which frequency. So does this mean that if generator levels down to -90dBm look OK, the limit I am able to test this way, would that also mean it should also be OK at -120dBm?
?
Yes, you are lucky. Because you where in OUTPUT mode at such a low level, many of the sensitive parts of the tinySA where internally disconnected. The input attenuator can take some input power if its only for a short time. Don't ask be to specify. The attenuator will have protected the mixer.
Wondering if it may still be possible there might be some additional attenuator stages that are used for signals lower than -100dB that may still be damaged?
?
If the linearity test resulted into a flat line and the selftest was OK everything should be OK down to -115 dBm. Below -115 dBm the output power error may become larger, as with all tinySA Ultra.
?
?
Regarding tests on the SA part, compared the Ultra to my original TinySA and set both to monitor the same span of VHF frequencies each with its original antenna. Saw almost identical readings from expected signals withing that range. One repeater was being shown as -80.0dBm on the Tiny and -79.8dBm on the Ultra, so it looks like the SA part of the Ultra is also working as expected.
?
Indeed
?
?
In closing, are there any other tests or calibration routines that you would recommend to run on the Ultra (aside from the SA self test which also did pass earlier) and that might apply in this scenario with the temporary overload of the RF port? Especially given the attenuator was being used at almost at the maximum range, and the linearity tests seem to be only testing between 28 and 1 dB attenuation.
?
Again, don't bother about the numbers, the whole range has been tested.
?
?
--
Designer of the tinySA
For more info go to

 

Thank you for the feedback Erik.
?
Earlier I was just going to buy another unit from R&L but they are currently out of stock because shipments seem to be behind schedule due to Chinese holidays, or so they said. But then I saw the newer ZS407 model which is in stock and I am tempted to get it. Guess that one just adds an even further extended SA frequency range which I don't think will ever need, but given the very positive experience so far with my current Ultra perhaps a worthwhile upgrade path, and also another spare unit just in case. It has often saved me from having to carry around a 40 pound service monitor when I am not going to need a fully comprehensive test suite.
?
Thanks again.

1 - 5 of 5