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settings tiny sa for transmitter harmonics
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You can leave everything on automatic at first
Most important is to ensure the fundamental is entering the tinySA between -30dBm and -10dBm Then use the MEASURE/HARMONIC function, enter the frequency of the fundamental Then use LEVEL/ATTENUATE to switch to manual attenuation and increase the attenuation till the harmonics are just measurable, e.g. the markers are on the harmonics This ensures you are not measuring the internally generated harmonics but the harmonics generated by the trasnceiver If the harmonics are below -60dBc (more then 60dB below the fundamental) they may be in the noise floor and you may have to reduce the RBW to be able to see them. If the harmonics (in dBc) do NOT change when you change the attenuation up or down 5dB you can be sure you are measuring correctly? -- For more info on the tinySA go to https://tinysa.org/wiki/ |
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Carlos,
In addition to Erik's directions, please be sure to use a 50DB attenuator on the input to the TinySA.? I built a 50DB tap and connected it to a 100watt dummy load.? I then use a step attenuator between the tap and the TinySA. Rig --------TAP--------Dummy Load ? ? ? ? ? ? ? ? ? | ? ? ? ? ? ? ? Step Attenuator ? ? ? ? ? ? ? ? ? | ? ? ? ? ? ? ? TinySA Here is a link to a paper on how to build a 50DB tap: It includes a parts list. I purchased the step attenuator from Amazon: You will also need the adaptors to match the coax connectors. I found the above to be easier to use than going through the TinySA menu system and adds a level of protection before you turn it on if you set the step attenuator for the maximum attenuation before turning on anything.? Overkill, but I am paranoid. If you need to measure harmonics that fall above 100MHz, you may need to characterize the tap.? That does require a second instrument (which I highly recommend), a NanoVNA.? I adjusted the capacitor across the 50ohm resistor to keep it flat to 150MHz.? Beyond that value, I have not tried to measure a signal, so I cannot say how well the setup works above 150MHz.? That upper limit is for the Harmonic you want to measure, not the fundamental. You can always buy a 100watt, 50DB attenuator, though they are costly unless you want to trust AliExpress. 73 Evan AC9TU |
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Carlos etal, Many thanks for all of the valuable information shared in this group. A home brew 6-60db 3Mhz to 500Mhz?has been designed by ZL2PD and is published here: This could complement the 50dB attenuator described by Evan. Andrew Woodfield [ZL2PD} is a luminary of design and build of practical electronic items especially for amatuer radio operators. Please see his website and say thankyou. He takes the time to document the use, principle and construction of all of his projects in a manner mere mortals like me can understand. The hobby owes him a debt of gratitude and I will not cease singing his praises for the help his projects have given me. He is often published in the Magazine Silicon Chip: an Aus-NZ electronics magazine. Thanks and stay well everybody. Cheers John B VK3JWC Regards and thanks
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John Baker
Senior Research Fellow
Dept of Mechanical and Aerospace Engineering
Postal - Monash University, Clayton, VIC 3800, Australia
Mob 0412 831 410 ---------- Forwarded message --------- From: Evan Hand <elhandjr@...> Date: Sat, 4 Jun 2022 at 23:00 Subject: Re: [tinysa] settings tiny sa for transmitter harmonics To: <[email protected]> Carlos, In addition to Erik's directions, please be sure to use a 50DB attenuator on the input to the TinySA.? I built a 50DB tap and connected it to a 100watt dummy load.? I then use a step attenuator between the tap and the TinySA. Rig --------TAP--------Dummy Load ? ? ? ? ? ? ? ? ? | ? ? ? ? ? ? ? Step Attenuator ? ? ? ? ? ? ? ? ? | ? ? ? ? ? ? ? TinySA Here is a link to a paper on how to build a 50DB tap: It includes a parts list. I purchased the step attenuator from Amazon: You will also need the adaptors to match the coax connectors. I found the above to be easier to use than going through the TinySA menu system and adds a level of protection before you turn it on if you set the step attenuator for the maximum attenuation before turning on anything.? Overkill, but I am paranoid. If you need to measure harmonics that fall above 100MHz, you may need to characterize the tap.? That does require a second instrument (which I highly recommend), a NanoVNA.? I adjusted the capacitor across the 50ohm resistor to keep it flat to 150MHz.? Beyond that value, I have not tried to measure a signal, so I cannot say how well the setup works above 150MHz.? That upper limit is for the Harmonic you want to measure, not the fundamental. You can always buy a 100watt, 50DB attenuator, though they are costly unless you want to trust AliExpress. 73 Evan AC9TU |
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