Thanks for the presentation of the inductively coupled RF tap practical design demo. At 14.20 on when speaking of the Gain of the contraption you mistakenly mentioned it to be S11 parameter instead of S21. S11 is the Return Loss (or the SWR in the amateur radio operators' world) which you explained earlier. It's always better to use a thin gauge wire to cover only 270 degrees of the circumference of the torroid to avoid the interwinding capacitance affecting the performance at the higher end of the HF spectrum. You can afford to put an extra layer of the heat shrink tubing for a snug fit. A small value compensation capacitor (say a "gimmick capacitor" rightly trimmed up) may also be tried to achieve a flat frequency response. De VU2RZA
I'm so glad I stumbled on your channel, you explain things so well! Thank-you. I'm returning to ham radio after a hiatus of 30 plus years and want to build some of my own ancillaries. The information in your videos make it possible for me to understand what I am doing and why. 👍
I read that these are current samplers and are much more reliable than a voltage sampler as they have a more flat response across the frequencies. Definitely need one. I have a really old Agilent network vector analyzer that O want to use with various power levels. Do you use a step attenuator to zero out the fundamental? We did this as part of our test procedure when I did my co-op work term at Nautel EDIT, I just checked, my spec analyzer, the S input will take 30dbm (1W), and the RAB inputs will take 20dbm(100mW). so if I test a 1kwTxmttr, I would need the 30dbm for the S input and 40db for the RAB inputs, anything more and I could just put an inline attenuator between the sampler and input to my s.a. 73!!
Need help clearing up a little confusion. So you say use shielded Coax to support the ferrite core with the windings. Ok, I have a core ready for install in my sampler in box. You mention grounding the shield at only one end, Ok, I get that as to not create a ground loop which would cause issues, read that in a book for Ham construction. You mention capacitive coupling, not a good idea, I get that, unless you actually want coupling( not in this case, but would want coupling in a multi pass attenuator) I saw one of those in the book I am reading or at least I think so, the picture and text from that section discussed all of that but we're not here for that right now. So my question is this. If the shielded lead is grounded, wouldn't that eliminate RF which is what we need to induce current in the toroid coil?
It has nothing to do with ground loops. Grounding the coax foil at one end turns it into an electrostatic shield rather than an electromagnetic one. It blocks the electric fields that would otherwise capacitively couple the center of the coax to the secondary windings in the torroid without blocking the magnetic fields the transformer needs to operate. If the shield wasn't there, that capacitive coupling would otherwise negatively affect the high frequency performance of the device. The metal box you put everything into is connected to both ends and is the electromagnetic shield.
Would it be possible to build a longer box, and set up multiple couplings within the same box to have different -db samples in one box? For instance a box with a 30 and 40dbm attenuation on separate bnc connectors? One longer piece of coax with the shield grounded at the input side, and a separately wound transformer for each output? I suppose i dont see why it wouldnt work but rf is weird
@@carminecampo2045 I'm getting the material now. Just one thing I've noticed. As per last chart Port 2 reads the sample at -36db ish, so shouldn't it be rather a -36 db sampler? I've seen -32 on the label there. Thanks for you answer
@@IZ0MTW The calculated value is -30dB. The measured value with a watt meter was -32dB. The VNA showed -36dB, however there are other factors that effect the gain (coax looses, etc.)
could one put multiple ferrite coils on one piece of coax as demonstrated the in this video, this way only one box with multiple taps, or am a missing something with doing that. TheDM (UK)
Now i see you didn't add resistors on one of the boxes i have watched other videos on the subject they add like 49 to 51 ohm resistors? Looks like to me it's a internal resistance from to inductor? Am i missing something here ?
hi sometimes we have a rf signal that it's not repeatitive sampling this signals requires a very high samle rate analog to digital converters how can we downconvert this not repeatitive signals and use low sample rate analog to digital converters ? is there anyway?
I am using several 24 volt power supplies in a parallel / series configuration to provide up to 80 amps at 54 volts. The power supplies come out of a control system for a power plant. The manufacture is Phoenix.
What size wire did you use and how many wraps? I could only get 24 wraps with 22ga magnet wire. So I cannibalized an old CRT television I pulled out of the recycling center. I pulled the yoke (deflection coil) off the neck of the CRT and used the wire from that and got 32 wraps on the 50-43 ferrite. A piece of shrink tube on the RG-303 worked perfectly.
one can use a larger toroid, all you have to worry about it the material so use a 68/43 or larger. The wire size does not matter either unless you use it as a power tab. There is one caveat with the design though, it should be internally terminated with a resistor tap to get more bandwidth out of it. (original schematic) Otherwise looking at harmonics becomes inaccurate without correction table.
Poorly done..the inductive pickup has BW limitations although mostly linear. The coax with broken shield is a big discontinuuty and will cause reflection A microstripline and surface mount resistors are the correct method.
Thanks for the presentation of the inductively coupled RF tap practical design demo.
At 14.20 on when speaking of the Gain of the contraption you mistakenly mentioned it to be S11 parameter instead of S21.
S11 is the Return Loss (or the SWR in the amateur radio operators' world) which you explained earlier.
It's always better to use a thin gauge wire to cover only 270 degrees of the circumference of the torroid to avoid the interwinding capacitance affecting the performance at the higher end of the HF spectrum. You can afford to put an extra layer of the heat shrink tubing for a snug fit.
A small value compensation capacitor (say a "gimmick capacitor" rightly trimmed up) may also be tried to achieve a flat frequency response.
De VU2RZA
I'm so glad I stumbled on your channel, you explain things so well! Thank-you. I'm returning to ham radio after a hiatus of 30 plus years and want to build some of my own ancillaries. The information in your videos make it possible for me to understand what I am doing and why. 👍
Thanks for you feedback. I'm happy to help! Regards
A great overview of RF sampling and video. I have another that I built but it's not very stable/repeatable. Building your example now Thanks!
Very helpful video. Thanks for sharing your skills!
Nice video 🎉
So you basically have built a CDN for the DC range of under 10GHz😂great👌😎
I read that these are current samplers and are much more reliable than a voltage sampler as they have a more flat response across the frequencies. Definitely need one. I have a really old Agilent network vector analyzer that O want to use with various power levels. Do you use a step attenuator to zero out the fundamental? We did this as part of our test procedure when I did my co-op work term at Nautel EDIT, I just checked, my spec analyzer, the S input will take 30dbm (1W), and the RAB inputs will take 20dbm(100mW). so if I test a 1kwTxmttr, I would need the 30dbm for the S input and 40db for the RAB inputs, anything more and I could just put an inline attenuator between the sampler and input to my s.a. 73!!
Interesting... Every little nugget of knowledge helps.
Need help clearing up a little confusion. So you say use shielded Coax to support the ferrite core with the windings. Ok, I have a core ready for install in my sampler in box. You mention grounding the shield at only one end, Ok, I get that as to not create a ground loop which would cause issues, read that in a book for Ham construction. You mention capacitive coupling, not a good idea, I get that, unless you actually want coupling( not in this case, but would want coupling in a multi pass attenuator) I saw one of those in the book I am reading or at least I think so, the picture and text from that section discussed all of that but we're not here for that right now. So my question is this. If the shielded lead is grounded, wouldn't that eliminate RF which is what we need to induce current in the toroid coil?
It has nothing to do with ground loops. Grounding the coax foil at one end turns it into an electrostatic shield rather than an electromagnetic one. It blocks the electric fields that would otherwise capacitively couple the center of the coax to the secondary windings in the torroid without blocking the magnetic fields the transformer needs to operate. If the shield wasn't there, that capacitive coupling would otherwise negatively affect the high frequency performance of the device. The metal box you put everything into is connected to both ends and is the electromagnetic shield.
Would it be possible to build a longer box, and set up multiple couplings within the same box to have different -db samples in one box? For instance a box with a 30 and 40dbm attenuation on separate bnc connectors? One longer piece of coax with the shield grounded at the input side, and a separately wound transformer for each output? I suppose i dont see why it wouldnt work but rf is weird
I would like to know this as well.
Ben fatto. Lo proverò con il mio generatore dual side band fatto con il Raspberry 4b
Absolutely interesting. Thanks for sharing. I’ll definitely build one. 73
Great, I'm glad you found it helpful!
@@carminecampo2045 I'm getting the material now. Just one thing I've noticed. As per last chart Port 2 reads the sample at -36db ish, so shouldn't it be rather a -36 db sampler? I've seen -32 on the label there.
Thanks for you answer
@@IZ0MTW The calculated value is -30dB. The measured value with a watt meter was -32dB. The VNA showed -36dB, however there are other factors that effect the gain (coax looses, etc.)
@@carminecampo2045 very good thank you!
could one put multiple ferrite coils on one piece of coax as demonstrated the in this video, this way only one box with multiple taps, or am a missing something with doing that. TheDM (UK)
I just built a dual coil sampler last night based on this design. It works
Great, thx !
Now i see you didn't add resistors on one of the boxes i have watched other videos on the subject they add like 49 to 51 ohm resistors? Looks like to me it's a internal resistance from to inductor? Am i missing something here ?
What size Ferrite Toroid Core did you use
What Jiffy Box number did you use?
hi sometimes we have a rf signal that it's not repeatitive sampling this signals requires a very high samle rate analog to digital converters how can we downconvert this not repeatitive signals and use low sample rate analog to digital converters ? is there anyway?
Is the ground of the BNC and the ground of the RF in/RF out connected together through the case?
Awesome!
Thanks!
Hi , is it possible to add 3 more sample ports , ie a bigger box with 2 bnc sample ports on either side?
Much appreciated
PeaceFromOz😊
Yes, I would shield each section with sheet metal to reduce interaction. Regards, RF Man
@@rfmanchannel6915 thanks for the reply...much appreciated.
PeaceN73Oz
Hello Mr. what lab power supply do You use for ldmos amplifiers to supply them with ~50V ?
I am using several 24 volt power supplies in a parallel / series configuration to provide up to 80 amps at 54 volts. The power supplies come out of a control system for a power plant. The manufacture is Phoenix.
You didn't show the voltage settings or scale on the 'scope!
order a ft-50-43 but the center was to small after wrapping wire. coax wouldnt fit..is there a bigger center hole with the ft-50-43
What size wire did you use and how many wraps? I could only get 24 wraps with 22ga magnet wire. So I cannibalized an old CRT television I pulled out of the recycling center. I pulled the yoke (deflection coil) off the neck of the CRT and used the wire from that and got 32 wraps on the 50-43 ferrite. A piece of shrink tube on the RG-303 worked perfectly.
one can use a larger toroid, all you have to worry about it the material so use a 68/43 or larger. The wire size does not matter either unless you use it as a power tab. There is one caveat with the design though, it should be internally terminated with a resistor tap to get more bandwidth out of it. (original schematic) Otherwise looking at harmonics becomes inaccurate without correction table.
Poorly done..the inductive pickup has BW limitations although mostly linear.
The coax with broken shield is a big discontinuuty and will cause reflection
A microstripline and surface mount resistors are the correct method.
Which type is suitable for continuous monitoring of the transmitter, without wasting much power.
Great. video! 73. WAA4ITD