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@uncleTedLol 23 сағат бұрын
This is brilliantly presented, thanks for your sharing your expertise!
@ebones6957 Күн бұрын
Ok, the matching network is used to match the transmitter output impedance to that of the transmission line/antennae load. Isn’t that the same as the plate tune and load controls of the transmitter? Is the match box just used to increase the range of input and output impedance matching? There are many videos on how to adjust the controls on the match box/“tuner”, none mention how do you set 😮the plate and tuning controls of the transmitter ahead of the match box. Does one first tune (resonate) the transmitter plate into a 50 ohm load, and then adjust the loading for max power output, to assure a 50 ohm input impedance? Then connect the match box,and then adjust the match box controls while connected to the antennae? Could you build a transmitter without plate tune and load controls and just use a transmatch?
@eie_for_you Күн бұрын
You are right, the "plate and load" adjustment are a matching network of themselves. The difference is what they are actually matching in terms of impedances. The output impedance of the final amplifier is not naturally 50 Ohms or even close to it. It's output impedance is approximately the same as the plate load. At resonance, this is pretty high which is why we dip the place current. The purpose of the plate and load adjustments is designed to translate the high output impedance of the finals to a 50 Ohm environment. It has been a very, very long time since I owned a rig with plate and load adjustments to be made. If it were me ... I'd set them in the "starting position" as dictated by the radio's manual first. Then dip the plate. Now adjust the antenna tuner for best SWR. I would then go back and adjust the plate and load as per the radio's manual. And finally, I'd give the antenna tuner its last adjustment. 🙂
@spheretical3609 Күн бұрын
Very appreciative of the practical nature of your videos and subsequent advice or findings. Your increasing production values are noticed and appreciated.
@eie_for_you Күн бұрын
Thank you so much! I'm always looking to do it better. Never stop learning! 🙂
@WECB640 Күн бұрын
This was fantastic! Ralph, I'd never heard of "early voltage" before. Thank you for explaining. Also, it was eye opening to learn that the linearity of a transistor changes because of this early effect. I know what I'm about to say uses the wrong terminology, but it's almost like the transistor has an inherent "Q", and that it's variable. Perhaps what I should say is Beta, not Q. My mind then asks the question....do vacuum tubes also have an "early voltage", or does this only pertain to low impedance current driven devices? Looking forward to your reply. 73 OM
@eie_for_you Күн бұрын
Thanks! I'd learned of all of this back when I was in engineering college, but had forgotten a lot of it through disuse. It is nice to have this stuff now coming back. I think vacuum tube have their own brand of things like this including the Miller Effect which affects semiconductors, too. (that is in the next video). Because of the nature of the Early Voltage, I think this is specific to semiconductor devices and, maybe, to BJTs in specific. 🙂
@MarcelGoedraad Күн бұрын
Dear Ralph Gable, First of all I would like to thank you for all the lessons in the RF domain, Too bad I didn,t have a teacher like you at school. Can you also explain how you can safely (hot) measure the RF power amplifier from 5 to 35W? How can you measure the input impedance of the RF amp (S11) and of course the gain of the RF amp (S21). I understand that you have to increase the output of the VNA to about 5W instead of 1mw (0 dbm) that comes out now. (and a high power attenuator after the RF amp). I own an Agilent ENA VNA, but I don,t dare to use it without a good explanation and so far I have only measured passive things. Regards, Marcel (from the Netherlands)
@eie_for_you Күн бұрын
Now **THAT** is a good question! The problem we run into right out of the gate is amplifier drive. Like my little VHF amplifier will not switch into transmit mode until the input power reaches a certain level. So (just thinking out loud), I'd have to have an amplifier to bring the port 1 signal up to the required drive level of the target amplifier. Now comes the "fun" part ... calibration and measurement. I have a Bird inline wattmeter. It uses different plugins to configure it for frequency and power levels. It also has a plugin for an RF sampler which provides 50 dB of attenuation between the sampled power and the sample output. So, step 1 for me is to calibrate using all of this without the target amplifier in place. VNA Port1->Preamp->Bird->Dummy load. The -50 dB sampler output from the Bird-> VNA port 2. Calibrate as a through measurement. Remember, check the input level limitations of your VNA BEFORE doing anything. My Tektronix VNA is conservatively 0 dBm. According to the charts I have, +50 dBm is 100 Watts. So the output of my Bird sampler will be 0 dBm with 100 watts running through it to the dummy load. You *may* have to put an attenuator between the sampler output and VNA port 1 to make sure you are not exceeding the VNA's limits. Once everything is calibrated as a through measurement, then insert the target amplifier and make your through measurement as usual. Input impedance-wise ... for an amplifier like mine with the power sensitive transmit-receive switch, we can only measure the input impedance of the power amplifier if we can somehow trick it into thinking it needs to be in transmit mode. And don't forget to put a dummy load on the output of the amplifier. I hope this gives you some ideas. Always, always be careful. Attenuators are your friend to protect your VNA! 🙂
@MarcelGoedraad Күн бұрын
Thank you for your detailed explanation. Fortunaly, I also have a Coaxial Dynamics 87015 Directional Coupler (-50db 50 to 500 mHz and a Bird 50 ohm line section with above components, a hot S11 measurements should be possible with 5W, right? So I never understood the proper setup and calibration. A video would certainly make many happy. I,m sure several people encounter this. Regards, Marcel
@eie_for_you Күн бұрын
@@MarcelGoedraad The problem is the VNA has to see the input of the amplifier directly to properly do an S11 measurement. In my mind, I'd be thinking about taking the cover off and figuring out how to "manually" put the amplifier in transmit mode. I am hoping you have what you need at this point. As far as a video goes, I'd have to either create or buy a 5 watt preamplifier to do this. I have nothing "in house". Worth thinking about, though because it sounds like fun! 🙂
@ornithopterindia Күн бұрын
👍Thank you sir.
@eie_for_you Күн бұрын
You are welcome, my friend. 🙂
@RensePosthumus Күн бұрын
This was a good and fine video for the day. Thanks.
@eie_for_you Күн бұрын
You are welcome! 🙂
@davidluther3955 2 күн бұрын
THAT ELECTRON SURE IS HAPPY!
@eie_for_you 2 күн бұрын
He was! LOL🤣
@davidluther3955 2 күн бұрын
HOW DID YOU COME UP WITH THE VALUE FOR THE SWAMPING RESISTOR OR,WHAT RULE OF THUMB DID YOU USE?
@eie_for_you 2 күн бұрын
I'm not familiar with the term "swamping resistor," but I assume you are referring to the upper emitter resistor. I start with the standard method of determining the emitter resistor value to establish the DC operating point. This is Re(total). The gain of a common-emitter amplifier with an emitter resistor is *approximately* equal to the collector resistor value divided by the emitter resistor value. So, I say, "I want a gain of 'g' and my collector resistor value is 'Rc', so my un-bypassed emitter resistor value needs to be Re(gain)=Rc/g. This value is smaller than Re(total). So Re(bypassed) = Re(bottom) = Re(total) - Re(gain). Re(gain) becomes the top, un-bypassed emitter resistor. Hope this makes sense. 🙂
@davidluther3955 Күн бұрын
THANK YOU!ALL THE ACTIVE CIRCIUTS TEXTBOOKS I HAVE CALL IT A SWAMPING RESISTOR,BECAUSE IT IS SUPPOSE TO REDUCE THE BAD EFFECTS OF r'e.
@cold3lectric 2 күн бұрын
you have this kindly concerned raised-eyebrow look on your face, letting me know it's indeed tricky material and my bafflement is valid lol, thankya my goodman!
@eie_for_you 2 күн бұрын
You are very welcome! Yeah, there is a LOT there and it *can* be confusing. 🙂
@buddyhoover57 2 күн бұрын
Excellent demo. I'm a very new ham and thoroughly enjoyed the explanation.
@eie_for_you 2 күн бұрын
Thanks so much! I am so glad that this was helpful.🙂
@Kref3 3 күн бұрын
Thanks a lot for your explanations. I am an electric engineer in the high voltage power transmission field (gas insulated high voltage switchgears) and while I have learned this more than two decades ago, I have not used it ever since and as we all know: use it or lose it. Now I had to dig into this again, because when we commission a new switchgear, we do a partial discharge measurement and we measure the PD signals by detecting their UHF signals. Sometimes there are background noises making the measurement in the time domain impossible, although this is required to check for particular patterns. So now I start using spec analyzers to determine the disturbances and build specific stub filters which then allow me to measure in the time domain without any interference. Your video was really helpful to bring the stuff back to mind.
@eie_for_you 3 күн бұрын
WOW! And, this stuff can be a bit of a head breaker! I'm so glad that these videos are helping to bring all this R.F. magic back into memory! 🙂
@ahmednor5806 3 күн бұрын
🙏🙏🌹🌹🌹🌹
@eie_for_you 3 күн бұрын
I'm very glad you found this to be helpful! 🙂
@Jystify 3 күн бұрын
Thank you, sir, for your extensive knowledge. May God continue to Bless your soul.
@eie_for_you 3 күн бұрын
You are very welcome, my friend! ... and He has blessed us over and over again. 🙂
@anthonyselby8337 4 күн бұрын
loving your videos very well explained only wish i'd found your channel sooner keep up the excellent work
@eie_for_you 4 күн бұрын
Thanks so much! I am really glad that you are enjoying them. By God's grace, the videos will keep on rolling out! 🙂
@anthonyselby8337 4 күн бұрын
thank you very good explanation as a novice hobbyist trying to rap my head around electronics this video actually explains it very well
@eie_for_you 4 күн бұрын
Thank you! I am so glad that this helped you understand what Q is. 🙂
@rhondafox7131 5 күн бұрын
To get a 1 to 1 standing wave.
@eie_for_you 4 күн бұрын
Gotcha. 🙂
@rhondafox7131 5 күн бұрын
You need a feed point impedance of 200 OHMS for a 4:1 balun called a beta match.
@eie_for_you 4 күн бұрын
And that is exactly what I applied to this antenna ... a 4:1 BALUN using coax. I have a detailed video on the how and why of such a coax-based 4:1 BALUN here: kzfaq.info/get/bejne/nK1njdOkz762h2w.html 🙂
@ricksargent8754 5 күн бұрын
Excellent explanation. Thanks
@eie_for_you 4 күн бұрын
Thank you! ... and you are very welcome! I am so glad that you found it helpful. 🙂
@thomasmaughan4798 5 күн бұрын
11:30 The presence of harmonics of the modulating frequency is a defect or deficiency; nearly impossible to avoid but not really part of the balanced modulator process. The more linear the modulator the more perfectly the presence of a pure sinewave modulation will produce exactly one upper sideband and one lower sideband frequency peak. These sidebands can modulate *each other* and since they are 2 KHz apart, that is where your 2 KHz harmonics are appearing, a phenomenon called IMD, InterModulation Distortion. As you can see, these IMD sidebands greatly exceed the expected transmission bandwidth. The absence of 1 KHz sidebands tells me the balanced modulator is highly linear and effective; but the IMD sidebands tells me the buffer amplifier that follows is not perfectly linear and is allowing the upper and lower sidebands to modulate each other. This is also the main difference between one of your top name-brand radios and cheap radios; is how well they resist IMD during receive and avoid it on transmit.
@eie_for_you 4 күн бұрын
Very true! And, unfortunately, this was a realization which occurred *after* the video was posted and it had a lot of history. I added additional text to the description to this effect. Unfortunately, YT does not allow me to update any given video with a new video. Otherwise, I would have made this note to an updated video. I can only release a completely new video and totally delete the old one, losing ALL of the history (and benefits) of the old one. 😞
@dalependleton6420 5 күн бұрын
Too much info too fast.
@eie_for_you 4 күн бұрын
The good news is ... you can stop and start the video and you can also watch it more than once. 🙂
@siggi51991 6 күн бұрын
Love it 😊😊😊
@eie_for_you 6 күн бұрын
I'm so glad it was helpful! 🙂
@siggi51991 6 күн бұрын
Love it
@eie_for_you 6 күн бұрын
Thank you! 🙂
@gregory-hm9gm 7 күн бұрын
Thank you. What a brilliant explanation!
@eie_for_you 6 күн бұрын
You are welcome and thank you! 🙂
@W1RMD 8 күн бұрын
I'm late to make this comment, but you have a crystal ball! I've just rebuilt a stepped attenuator that I got at a hamfester 30 years ago, never used it because it had broken resistors in it from improper disassembly (by me?) and was wanting to see how to check it with my NanoVna. The NEXT DAY after getting it all back together you do a video on it! Thanks and 73!
@eie_for_you 8 күн бұрын
WOW! Perfect timing! It'll be interesting to learn how well you did in rebuilding the attenuator. I am very glad the video was helpful. You are very welcome. 73's my friend. 🙂
@davidluther3955 8 күн бұрын
AS USUAL EXCELENT LECTURE.I AM GLAD YOU TALKED THE SUBSCRIPTS,SO MANY OF MY TEXTBOOKS GET IT ALL WRONG FOR,FOR REASON,AS THOUGH THEY WERE ON DOPE OR SOMETHING.
@eie_for_you 8 күн бұрын
Thank you! 🙂
@arnolddebeer3506 9 күн бұрын
Good info. Thank you very much .......
@eie_for_you 8 күн бұрын
You are very welcome! I am so glad that you found this to be helpful. 🙂
@davidluther3955 9 күн бұрын
WHERE DID YOU GET THOSE RESISTOR NUMBER VALUES FROM YOUR JUNCK BOX?THEY DO NOT SEEM LIKE STANDARD VALUES.
@eie_for_you 9 күн бұрын
Many of my resistors are 1% resistors. Those folks who are used to the standard resistors values of the 5% and 10% variety (e.g. 27K, 33K, etc), these look pretty odd (and they are! Like 4.99K!?). Here is a great chart for you ... dazyweblabs.blogspot.com/2013/09/standard-resistor-value-chart.html 🙂
@davidluther3955 8 күн бұрын
@@eie_for_youTHANK YOU!
@eie_for_you 8 күн бұрын
@@davidluther3955 You are welcome! 🙂
@darylcheshire1618 9 күн бұрын
I have ordered one.
@eie_for_you 9 күн бұрын
They *ARE* an amazing tool! 🙂
@davidluther3955 11 күн бұрын
WHEN I WAS IN COLLEGE TRYING LEARN ALL THIS STUFF WE NEVER HAD SUCH GIFTS AS THIS.ABSOULTY INTRIGUING!
@eie_for_you 11 күн бұрын
Thank you! I was fortunate to have had a very good circuit analysis professor. We used the school's main frame to solve circuit analysis problems. We used a lot of linear algebra using the APL programming language at Syracuse University. 🙂
@carlosjsd4348 11 күн бұрын
Excelent thank you
@eie_for_you 11 күн бұрын
Thank you and you are very welcome! 🙂
@ChrisAthanas 12 күн бұрын
5:14 a “pip” is a small hard seed Maybe you meant to say “peak”?
@eie_for_you 12 күн бұрын
Probably a better term ... but you got the point. 🙂
@anlpereira 12 күн бұрын
This is what I was looking for a few months ago. I have one NanoVNA V2 and would like to make a transformation like this. I'm doing a PCB Board for ESP32 ICs and I found in the datasheet that its RF output has a 35Ohm + 0j output impedance and I only have a 50Ohm chip antenna. Please, tell me how to calculate and measure the CLC matching circuit using the NanoVNA. I need to calibrate it to behave like a 35Ohm output to measure the CLC matching circuit to 50Ohm. I want to use this method to tune the antenna kzfaq.info/get/bejne/qMiIpJOL3NCphKM.html to make its Return Loss near or better then -20db. Thank you very very much.
@eie_for_you 12 күн бұрын
The return loss currently sits at -15.1 dB without doing anything but connecting the two together. Also note that the physical traces on the PCB need to be impedance matched. See this for that: kzfaq.info/get/bejne/gJ6Gh5OC3dSXYZ8.html You could just use a resistive matching L network like I speak about in this video (see the "go along with the video sheet...link in the description) OR you could use impedance transformation using a stub transform similar to what I talk about in this video: kzfaq.info/get/bejne/jLx1ndd4sZ3Io4E.html. Only you would be using PCB features to accomplish this.🙂
@anlpereira 12 күн бұрын
I tried the formula convertion but it is getting a negative square root if I use R2 = sqrt(35² - (50*35)) unless I use the module.
@eie_for_you 12 күн бұрын
@@anlpereira Aaaaaahhhh...this is because you swapped hi Z and low Z R2 = SQRT(Zhigh^2-(Zlo*Zhi))=SQRT(50^2-(35*50)) = 27.386 Ohms. Easy to make this mistake. 🙂
@anlpereira 12 күн бұрын
@@eie_for_you Hehehe. I used pcb trace impedance for 50ohm from JLCPB. How did you calculate that I would have a -15db return loss without any matching components? I’m a little confused yet about the use of my NanoVNA. Your videos are very very good for me. Thanks
@anlpereira 12 күн бұрын
Where I can find your email to send the pictures of my circuit? Thanks
@niggorr 12 күн бұрын
what a cool man i want to be like you when i grow up
@NikiBretschneider 12 күн бұрын
In my opinion you don't need to go through Open/Short/Load calibration steps as these are related to the S11 (CH0 in nanoVNA language) and you have turned all S11 traces off (for a good reason, 1st port is connected to the attenuator, so S11 depends mostly on the attenuator itself, not the DUT, because that added -88dB on the S11 is far below the nanoVNA's noise floor). Calibrating Through (which is related to S21) only should be enough. It's nothing bad on going through the whole calibration process, it's just not necessary in this particular case.
@eie_for_you 12 күн бұрын
This is very true and with my Tektronix VNA this is exactly what I do when doing through measurements only. With that said, this is the nanoVNA and it tends to want the whole enchilada even if it might not really apply. While it probably isn't technically needed, it never hurts to do it all. 🙂
@djkevy2006 12 күн бұрын
Hi I've tried making one of these 3 or 4 times and can't get any sort of match? I must be doing something wrong? What am I looking to measure on the nano is it impedance / swr or both ? What would your final calculated length of the balun be for 101.4mhz and the length of the tails ? I must be calculating wrong Thanks
@eie_for_you 12 күн бұрын
As shown in the video, I am looking at SWR. An important question ... Are you testing the BALUN with a fixed, metal film, 200 Ohm resistor or connected to the antenna? If connected to the antenna, are you *sure* that the antenna is, indeed, properly tuned to the target frequency? What is the characteristic impedance of the antenna by itself? You can measure this with your nanoVNA (kzfaq.info/get/bejne/ms10hpejz8iRd4k.html). Regarding the length BALUN coax...the final calculated length would depend on the velocity factor of the coax that you are using for the "BALUN Coax." If the VF of the coax is 0.66, then the BALUN coax should be on the order of 41.48 Inches or 105.37 cm long according to my calculations. This is using the 8% longer to accommodate for the pigtails and a frequency of 101.4MHz. Hope this helps. 🙂
@djkevy2006 9 күн бұрын
Hi thanks for the fast reply. Yes I was using a fixed metal film 200ohm resistor. Ok, so if I cut my coax to 41.48 inches then add my tales around 3inch ish ? then i should trim them back down to get the lowest swr ? I'll give it ago and post my results Thanks again Kev
@eie_for_you 9 күн бұрын
@@djkevy2006 I will look forward to seeing how it goes for you. Again...assuming a velocity factor of 0.66. 🙂
@Number4lead 14 күн бұрын
One of the earlier attempts to use the radio spectrum more efficiently. Now we have ctcss and other tones to help. Also trunking systems and other digital communication systems.
@eie_for_you 13 күн бұрын
Interesting thought. However, we are talking two different things here. SSB is mainly used in HF communications. CTCSS and so on are used with FM modulated signals in the VHF and up range. So, yes, the systems you speak of DO save spectrum space but do not apply to HF. 🙂