Re: Why transmitter power attenuator for TinySA?
Well if you want to measure spurious outputs from a transmitter the Tiny Sa can do that easily, but you must use an attenuation to keep the levels within the allowable limits. Some take the harmonics measurement with an appropriate attenuation, then add an additional attenuation and take the readings. In some cases the input of the Sa can be overloaded and it produces harmonics. By running the test that way you can be sure the trash is coming from the transmitter. You can use the Sa to verify compliance with FCC. Quite a few of the lower cost it's don't meet the spec. The Tiny Sa Ultra has a harmonics mode.
On Wed, Nov 13, 2024, 7:54?AM Fred Murray via <fredmurray919= [email protected]> wrote: ?
Never stellar, my aging mind deteriorates faster than I am aware of.
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I do understand why I should use an attenuator to protect various pieces of equipment from "excessive" rf.
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Maybe I misunderstand why anyone might want to connect the output port of an active transmitter to any port of a TinySA.
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Regarding the hf rf environment of my home, I have found a tv high pass filter to be of value for my sdr setup and TinySA use; in particular:
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Too much to learn and not enough mind or time.
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wa4hei
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Re: Why transmitter power attenuator for TinySA?
Maybe I misunderstand why anyone might want to connect the output port of an active transmitter to any port of a TinySA.
One of the primary uses of a spectrum analyser is to do various measurements on a transmitter; such as harmonic levels and spectral purity. These cannot be done accurately without a direct connection, albeit via attenuation of the required amount. 73 Jeff G8HUL
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Why transmitter power attenuator for TinySA?
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Never stellar, my aging mind deteriorates faster than I am aware of.
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I do understand why I should use an attenuator to protect various pieces of equipment from "excessive" rf.
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Maybe I misunderstand why anyone might want to connect the output port of an active transmitter to any port of a TinySA.
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Regarding the hf rf environment of my home, I have found a tv high pass filter to be of value for my sdr setup and TinySA use; in particular:
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https://www.amazon.com/Channel-Master-CM-3250-Removes-Interference/dp/B09D45W9TZ?crid=3PQAOWQS31FYB&dib=eyJ2IjoiMSJ9.Y2HOVCF212tTm66x7HgnXa_eg9UziRcmHiv4nRmMz-cphvGuVv1LsMv9aR946XSRSs8mKUIKrCYFaCV13vC3mGM3YzJCLuYxq7pq_yZUD0Mb9aACEIskW3BuKPi6QpfF8BxYxfxfb85OY9Clbm1vsg-WEN12SwtHlTdm3Z_x2GdgwZ5MfyiDnJK3ZnnSFaYS0vZ08vq4uf7s-qyqC1zhnGzKiLxcTiASf0SRdcIaxiU.KInQcucr-cRdaJSNTZKgFMmAScUyxz5b1bhZrJ6rzTw&dib_tag=se&keywords=high+pass+filter&qid=1731501343&sprefix=channel+master+high+pass+filter%2Caps%2C191&sr=8-1
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Too much to learn and not enough mind or time.
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wa4hei
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Does anyone read the specifications?? Or they may read them but have absolutely no understanding of what they entail.? Yes, for faithful representation of the input, -25 dBm is specified. ? In an attempt to keep things simple, every 10 dB is equivalent to multiplying by 0.1, or move the decimal point one place to the left.
5-watts: ? add 10 dB attenuator ?? end with 0.5 watts? 5-watts ?? add another 10 dB attenuator for a total of 20 dB ? end with 0.05 watts 5-watts ?? add another 10 dB attenuator for a total of 30 dB ? end with 0.005 watts 5-watts ?? add another 10 dB attenuator for a total of 40 dB ? end with 0.0005 watts 5-watts??? add another 10 dB attenuator for a total of 50 dB?? end with 0.00005 watts
We all (should have) learned base 10 arithmetic in grade school.? Logarithms in Jr. HS or beginning HS.??
Dave - W?LEV
Also be aware that even at -10dBm, which is well below the damage level, the TinySA may still be slightly overloaded and not give accurate results on some measurements. At least 60db of attenuation would be required for a 5W input.
An input of -25dBm or less is recommended.
73
Jeff G8HUL
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From: [email protected] <[email protected]> on behalf of Gary W9TD via <w9td=[email protected]>
Sent: 11 November 2024 18:43
To: [email protected]
Subject: Re: [tinysa] Setup FM mobile VHF transceiver's deviation with VaraFM
Todd,
You need 50 dB of external attenuation to keep the level at the Ultra at -10dBm or less. You also might be able to use the supplied antenna with your radio feeding a dummy load. You cannot use the VARA modem as it will not create a single frequency tone, you need an external audio source like Audigy on your computer to generate a tone and send it through the USB to the DRA-50.
Gary
W9TD
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Please keep in mind that you may get a high power "key click" when you activate the transmitter that could take out the front end of your Ultra whatever method you use.
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
I'd agree with Bruce, just observe the occupied bandwidth of your transmission, using a suitably narrow RBW setting.
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It will be close enough to the desired value.
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Regards,
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Martin
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On Mon, Nov 11, 2024 at 11:27 PM, Bruce Akhurst wrote:
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Use normal modulation and look at the resulting bandwidth (average a few sweeps)?
aim to get most of the bandwidth within the allocated channel bandwidth?
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
I am not sure if you can do the measurement with the VaraFM modem, the frequency of the tone has to be at the frequency that is required to get a null in the spectrum for the desired deviation.
In other words you have to calculate the frequency of the tone to match the deviation that you require.
73
Jeff G8HUL
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Also be aware that even at -10dBm, which is well below the damage level, the TinySA may still be slightly overloaded and not give accurate results on some measurements. At least 60db of attenuation would be required for a 5W input. An input of -25dBm or less is recommended. 73 Jeff G8HUL ________________________________________ From: [email protected] < [email protected]> on behalf of Gary W9TD via groups.io <w9td@...> Sent: 11 November 2024 18:43 To: [email protected]Subject: Re: [tinysa] Setup FM mobile VHF transceiver's deviation with VaraFM Todd, You need 50 dB of external attenuation to keep the level at the Ultra at -10dBm or less. You also might be able to use the supplied antenna with your radio feeding a dummy load. You cannot use the VARA modem as it will not create a single frequency tone, you need an external audio source like Audigy on your computer to generate a tone and send it through the USB to the DRA-50. Gary W9TD
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Re: Unable to Download Windows Software for the tinySA-App
I could use a link to that software, sir!
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madmaxfz@...
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
I¡¯d skip trying to manufacture a tone equivalent to the modulation and then bessel dip spotting. It will never tell you what you need to know?
Use normal modulation and look at the resulting bandwidth (average a few sweeps)?
aim to get most of the bandwidth within the allocated channel bandwidth?
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Gary:
Ok got it. Thanks
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Todd
AL7PX
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Since FW version 1.4171 where it was fixed that Big number was displayed on remote desktop, on the #ultra screen when Big number is activated, when accessing the menu again it stops doing scans alternatively and sometimes, when unchecking big number or exiting the DISPLAY menu to go to another menu (for example, ?to change the frequency), the #ultra seems stops measuring.
It also happens if you give them the commands using the console commands. This video with the 30MHz Cal signal shows what happens:
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In the photos we see the same UHF C21 (saved by a console program on SDcard) working under FW 1.4170 and later
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? ??  ? Also, the characters are now larger than in FW 1.4170 and earlier, and now when the number is long, they don't all characters fit on the screen
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Todd,
You need 50 dB of external attenuation to keep the level at the Ultra at -10dBm or less. You also might be able to use the supplied antenna with your radio feeding a dummy load. You cannot use the VARA modem as it will not create a single frequency tone, you need an external audio source like Audigy on your computer to generate a tone and send it through the USB to the DRA-50.
Gary
W9TD
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Hi Gary:
Thanks for the reply. So, can I use the VaraFM modem SW to apply to the 6 pin Mini din connector on the icom 208H? Adjust the amplitude to get the null on the carrier. What about just measuring the modulating signal from the VaraFM modem at the connector? (2vP-P is Icom's recommended level) The soundcard generating the Vara modulation is a DRA-50 with hardware adjustable out level. Does the Ultra have enough attenuation setting to accept the minimum of 5 watts of the icom transceiver? I have ordered a 30db attenuator also. Can the Ultra receive the signal through the supplied antenna instead of directly inputting? I haven't received the unit yet. Coming from China. Thanks.?
Todd
AL7PX
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Re: Setup FM mobile VHF transceiver's deviation with VaraFM
Todd,
Use a single tone and adjust the frequency for an expected Bessel null at the desired deviation and then adjust the level of the tone until you get the null. That tone level will be the correct level to set the VARA modem output to.
Gary
W9TD
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Setup FM mobile VHF transceiver's deviation with VaraFM
Does anyone have a procedure to setup FM deviation on a mobile VHF transceiver using a Ultra? The mode will be VaraFM Wide protocol.??
Todd
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Since this device modifies the original tinySA ULTRA circuitry, tinySA ULTRA's software is unable to set up the hardware circuitry correctly, so you will not be able to use tinySA ULTRA's firmware. Since the tinySA ULTRA's firmware contains a lot of data from our frequent long-term testing, the clone manufacturer cannot make the same measurements, so even if you use their modified firmware, you will not get consistent results with the tinySA ULTRA. Typically this is worse phase noise, more spuriousness, and inaccurate power measurements at certain frequencies.
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As I do not know anything about this device I can not help you
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Designer of the tinySA
For more info go to
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Hi Erik,
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Hereby the pictures of the version and the back op de analyser.
It is not the original analyser (sorry :-)).
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Re: Preliminary EMC testing with tinySA
Agreed, Keith Armstrong produces some brilliant material and he¡¯s a really nice bloke as well!.
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Bruce Akhurst
Gary W9TD