Thanks, man! Many do not have the need to know, so they do not seek the knowledge. 😞

WOW! I'm so glad that this helped the light go on for you. 🙂 I have an SDR that I've played with a bit (nothing serious...yet). Either I haven't found the right software to use with it or just haven't stumbled across the methodology. Not real impressed with its performance as an HF receiver. 😕

Thank you for the reply!I have the SDRPlay and use their SDRUno radio software or the RSP Spectrum Analyser, both are free to download. I am very satisfied with this SDR + software, but they are certainly nothing special or expensive. If it might interest you, I would be happy to send you some screenshots of both programs with "a vanished carrier" on them. Maybe the settings will tell you something. @@electronicsfortheinquisitiveex

Woohoo! Great news! I am so glad this helped! 🙂

Thank you! We use this method all the time to set the deviation on our repeater system ... both the CTCSS tone and the "program audio."

You are welcome! I have to agree with you! The pip on the S.A. is below visibility and I can still hear the tone. Using a narrowband CW receiver it does seem to be easier to judge when the carrier is completely extinguished.

And your comment just popped up in my list of comments! WOW! The Rigol RF generator I have (DSG815) goes to 1.5 GHz. I am very happy with it. Unfortunately, I have no recommendations for you except what I have found so useful, my own DSG815. Price point-wise, you are not going to get better for the $$ (my opinion)

I am glad you found this video helpful! How would I do it? I would use this method exactly as described with a signal generator and all. Replace the TNC with an audio signal generator connecting its output to the port where the TNC would be connected, select the appropriate audio frequency for your deviation (2.4 KHz/2.4048 = 998.0 Hz) and then adjust the output amplitude of the signal generator until you get your null. Now you know the amplitude you need as an audio input to your transmitter to produce the desired deviation - for your digital signal, I'd be concerned with peak-peak voltage. Replace the signal generator with your TNC at the transmitter's input and adjust the amplitude of the TNC audio output to be the same peak-to-peak output amplitude that you had with the signal generator. You could use the MAX/MIN method of measuring deviation that I describe in the next video (ukposts.info/have/v-deo/mYSne3mChaR4sas.html) to verify the final deviation. I hope this helps. :-)

Well, Neal, if you are going to be checking FM deviation using a microphone and speech, then I would suggest the "MIN/MAX" method instead. This is great for checking a dynamic. live signal like speech. My video on that can be found here: ukposts.info/have/v-deo/mYSne3mChaR4sas.html The Bessel-Null method only works with a single, specific tone given a desired deviation. CTCSS tone has to be shut off on the monitored RF. Hope this helps.

@@electronicsfortheinquisitiveex will thank you.i own the hp esa1500a and just got the rigol dsa815

@@Ibelieve218 It's a great spectrum analyzer for the money! I got the one with the tracking generator so I can use it for "response-type" measurements on filters and the like.

"The Handbook of Electrical Engineering", Research & Education Association, c.1996; Section D, page 70. Good luck in finding a copy. 🙂

Well, this depends on what device you are adjusting. If you are working on a radio transmitter, then you need to find out what the amplitude of the normal audio source is and where it is applied. Then you set up your audio signal generator to mimic the amplitude of the normal source and connect it to that input. The object is to choose a place where the audio we use to make the measurement "looks" like it is coming from the source it normally would be coming from, but is, in reality, our signal generator where we have control. If it were, for instance, an FM broadcast station, I'd connect my signal generator to one of the inputs to the control board and set the audio level to 0vu to run the test on the FM transmitter's deviation. In the case of the demonstration I performed in the video, I connected it to the external audio input of the RF signal generator. Hope this helps