Відео

Thank you! I thought it was quite cool to see how the controls of the tuner changed the way the trace looked on the VNA. 🙂

You are welcome!😁

You are welcome!😁

Thank you! You can use this procedure to measure the output impedance of that op amp at lower frequencies. You are welcome! 🙂

It most certainly will. Just remember ... you have to terminate the output of the attenuator with your 50 Ohm load as most attenuators expect to be terminated. 🙂

I have run into a lot of such misconception about Americans. As a product design engineer, I had to be concerned with this all of the time. I'm glad that I've been able to dispel one more misconception. Maybe you could point your head of development to this video(??). You are very welcome! 🙂

You are welcome! I knew they tried it in the states for a short time. Even now, there is copper coated aluminum wire that I have encountered which, if you accidentally scrape off the VERY thin copper coating, won't solder at all. 🙂

Well, my friend, you are not the first person to make this observation. You are right, this is what some schools teach. And I used to round things just like you suggest until such rounding caused real trouble in a design and I had to double back and recalculate. It never hurts to carry (many) more decimals than you actually need. Rounding *can* cause enough of a difference in the outcome to cause issues. This is especially true when there is a series of calculations, each depending on the results of the last. So, I carry a lot of decimals, rounding only when I have reached to final value. The results are that I have the absolute confidence that the number I have is right. I've never been burned by that. 🙂

I got them a LONG time ago at some sort of school "fire sale" ... way cheap! 🙂

Well, don't throw the baby out with the bathwater. They are helpful as even a very carefully tuned antenna (1:1 at a specific frequency) isn't going to be 1:1 when you leave the frequency that the antenna is tuned to. Also, some antenna types are, by definition, not going to present a 50 Ohm load. These will require impedance matching. Even as a properly tuned antenna for the antenna type, they will not present a 50 Ohm impedance. So, there are situations where impedance matching is required and this is where our antenna matching network (AKA: antenna tuner) comes in. 🙂

Oooooohhh yeah! The joys of lead free solder! I will not use lead free solder here in the shop. It is way too much of a pain. I have a pretty healthy supply of 60/40 solder so I don't think I will run out. When I first encountered the slot under an optocoupler I was puzzled. Then I learned about creepage. Mystery solved. Thanks! 🙂

@@eie_for_you NO 63/37 either!

@@W1RMD True that! 🙂

You are very welcome! 🙂

So very Very VERY true!! 🙂

I'm so glad that it was helpful to you! Thanks! 🙂

Is it spelled that way or is it "toot- a- loots"?

@@W1RMD LOL! I've always spelled it "toodle-oots" but MSWord's read aloud pronounces it very stupid. I have to spell it "toodle loots" for it. Internet search comes up empty (it guessed at "toddler boots" LOL!) 😀

Thinking out loud here ... The main difficulty here will be the inductance and capacitance associated with the resistor decade box. But, if you can keep your leads *SHORT*, at only 100 KHz you might be OK on that count. You can use the same process used in this video using a scope for the overall output resistance. But, if you are interested in impedances at specific frequencies, not you have to graduate to a signal/spectrum analyzer which will report amplitudes in terms of dBm and the problem here is that they will have a 50 Ohm input impedance. To avoid skewing the results, you would have to put a large value resistor between the pin and the input of the analyzer. This will form a voltage divider with the input impedance of the analyzer (50 Ohms) being the "output resistor" of the divider. Once you get all set up, the process is still the same as the video except now you are looking at frequency pips on the analyzer and the half voltage point is -6dB. Hope this helps. 🙂

@ thank you once again. I don’t know if I understood well. I have a tinySA ultra in my lab, a nanoVNA and an Oscilloscope for 100Mhz. The output voltage of the microcontroller is 3.3V.

Can you make a small video showing how to do with a SA?

@@anlpereira This might help ... I did this this morning (zipped Excel spreadsheet). This was a FUN experiment this morning: drive.google.com/file/d/1VUFedOKYQOkBsQDpsLz_FienDHG_0-HW/view?usp=sharing

@@anlpereira See my reply to you next post 🙂

Thanks, man! I am so glad you have been blessed by it! 🙂

You are welcome! 🙂

Yup! I've had to deal with conformal coating a LOT! And you are right, it IS a pain. All of the products we manufactured were intended for an outdoor location, so conformal coating was kind of a requirement to keep the circuitry itself clean. It was a protective coating as opposed to extending the creepage distance (although we DID enjoy that benefit on a few occasions). When we would have to work on boards, we used a specially formulated conformal coating remover which worked real nice. It was amazing how that coating just came right off. Worth every penny we spent on buying the right solvent. You are right, though. If you can avoid it ... avoid it! 🙂

Yeah ... free! 🙂

Thanks!

Oh yeah! I've seen that on high impedance timing circuits, too. Clean, clean clean!!! Thanks!🙂

Excellent comment!

@@W1RMD True that! 🙂

Thanks for the tip! 🙂

You are welcome! You are right! It is tough to find affordable copies of standards. We have to settle for older versions ... but, like I said, we need knowledgeable guidance not certification. 🙂

I am so glad that this met your need! You are very welcome! 🙂

Are these separate antennas or are they arranged as a single trapped antenna? 🙂

@ separate with separate feed lines running parallel to each other. Would consider traps, but can’t measure the resonant frequencies, plus they tend to be less efficient and the antennas are not very high (10-15 ft). 2meter at top, 6 meter below and off to the right of the 2, and 15 meter below the 6 running the width of the house.

@@Joe-ho6fo Ahhh... the next question ... are they separated by more than 1/4 wavelength? If so, you tune them like any other dipole. Cut long, then trim to length. The higher the frequency, the shorter the pieces you trim as you tune. If they are closer than 1/4 wavelength, then tune the lower bands first. In either event, this will take some iterations. Don't tune to the perfect frequency the first pass through. Get "close," but not exactly where you want them. Then the second pass bring them into tune right where you want them. Finally, third pass, check that nothing has moved. Remember, tuning has to be done in the same space that the antenna will live. Buildings, plants, wires and other environmental things can change the tuning. Hope this helps. :-)

Thank you so much! I suppose that Mhos might be an older term that has been replaced with Siemens in many places like they replaced "Cycles-Per-Second" with Hertz. Maybe I made a mistake using the older term. Yes, it is a bit funny that they just spelled Ohms backwards for conductance. 🙂

@@eie_for_you yes in English wiki they say it's an older term. Fun fact for me is that they also used the 180 deg rotated Ohm symbol (Greek omega) in the past for conductance (not only in Australia :)

@@martymctry20 No surprise! I still remember (in my teens) when we talks about kilocycles and megacycles and the like. I guess Mhos stuck, too! 🙂

Well ... don't count the one's you bought out without testing them first. Sometimes they can be surprising like the 100 Watt dummy load I bought (made in China ... of course). It tested way awesome! So, test before discard. 🙂

Yeah, that's one thing about putting these connectors on ... you need something like 100 watts or more. I use my soldering gun. 🙂

@ I have a 70 watt. Barely enough. Just bought a welder 250 w.

@@Joe-ho6fo Yeah, that's what I use now and it works great! Lot's of heat, fast to do the soldering before melting the innards of the coax. 🙂

I am so glad that you found it helpful! You are very welcome! 🙂

Thank you ... and you are very welcome! 🙂

Thanks! Yes, R.F. power does, indeed, affect the choice of capacitors. The voltage rating of the capacitor is the important specification. The higher the power, the higher the voltage rating of the capacitor. The issue I found with the high voltage capacitors was that they had a lower Q, meaning the trap wouldn't trap as much even squarely at its resonant frequency. There is a lot of debate and great dearth of information about choosing the right voltage rating for a trap capacitor given a particular power being used. This is, in part, due to the fact that the actual maximum voltage that will appear across the capacitor depends on the frequency that the trap is tuned to. I **THINK** 1.5 KV capacitor should be sufficient for 100 watts. Nonetheless, I built my own capacitor to use for my traps (see the video here: ua-cam.com/video/VIMhfX9quac/v-deo.html). Antenna Analyzer: There are some good ones like the RigExpert ($$-rigexpert.com/products/antenna-analyzers/#) and some not so good like the MFJ-259. If I were in your shoes, I'd much rather spend the money on a good nanoVNA (nanorfe.com/nanovna-v2.html). I say this because it will do soooooo much more for you that an antenna analyzer. It takes more work to use and learn to use (see my Play List on the the whole VNA thing), but it will open experimentation doors for you. I hope all of this helps! 🙂

So, I come back to you to get more information. A trapped antenna allows the same antenna to be used on two or more bands. So, I ask, What two (or more) bands is this antenna going to be used on? 🙂

@@eie_for_you 2 band vertical ant, only for CW portion. Vertical efhw 12m/17m with coax trap for 12m.

@@geirha75 Aaaaah! 12 m CW 24.89-24.93 MHz (U.S. allocation). There are a LOT of opinions out there regarding the frequency traps should be tuned to. If it were me, I'd be shooting for 24.9 MHz. This way the trap truly, really "hides" the rest of the antenna for the 12 m band. 🙂

I believe it can, though I've never tried it or simulated it. Each element's resonant frequency would have to conform the the same rules that would be used for a straight dipole configuration. You could give it a shot, simulating is with 4NEC2 (FREE antenna modeling software). :-)

Thank you so much! :-)

LOL!!! That is the wireless microphone transmitter and my cellphone "holster"! LOL!! :-D

Yes, yes ... I am remembering this, too (now). While this wouldn't work for connectors inside an electronic device, it would be feasible to work in those kind of instances. It really is a pretty cool idea! :-)

I am at a bit of a loss as to what you are trying to measure. Are you measuring the input impedance of your tinySA whose input limits are 1.5 V pk-pk? As a point of reference, 0dBm is 1 mW into a 50 Ohm load = 50 mV RMS = 141.4 mV p-p. Your 1.5V p-p = 530 mV RMS => 5.6 mW into a 50 Ohm load => 7.5 dBm. My nanoVNA output is below 0 dBm. :-)

@eie_for_you I want to know if I can directly connect output of nano VNA to tiny SA . Also what are limit of tiny SA.. Plz can u confirm..I just dont want to blow my tinysa

@@minazulkhan8287 Here is the LINK to the complete specifications for the tinySA: tinysa.org/wiki/pmwiki.php?n=Main.Specification Therein it states: "Absolute maximum input level of +10dBm with 0dB internal attenuation " Your nanoVNA max output is 0dBm (theoretically - but it is actually likely less than that). So, it looks like you are quite safe. 🙂

Thanks......it worked 😊.

@@minazulkhan8287 You are very welcome! 🙂

If it were me, Dave, I would use this one: www.digikey.com/en/products/detail/infineon-technologies/SPP80P06PHXKSA1/2081673 But I would put back-to-back Zener diodes between the gate and source. You could use something like this: www.digikey.com/en/products/detail/onsemi/MMBZ18VALT1G/1749023 which has both in one package. :-)

You are welcome. :-)

Ya know ... in times past these were tin plated. I see now, as I look at DigiKey, they have Gold and Nickel plated; I don't see any tin plated ones. Yes, Gold with Nickel are within the green region, but with a 300 ... just within the green region. Yes, Gold and Nickel are FAR better matches than Gold and Tin. :-)

Welcome to the brotherhood of hams!! 🙂 Don't forget to also take in this video on the reason behind all of the other pips on the sidebands: ua-cam.com/video/LtXLhsUYqGg/v-deo.html You are very welcome! 🙂

This is an interesting idea. I suppose that this might be a possibility in some situations. But it is way simpler just to be careful to use the right two metals together. It is very easily done if we just pay attention to what we are doing. 🙂

LOL😁

I kind of agree with you with a couple of caveats. The choice of connectors is always application specific. Additionally, not every connector is even available with gold as a contact plating option. I agree, mating cycles is a major consideration but only when there is some expectation that a connector is going to be subject to repeated mating cycles. When we consider the majority of applications for connectors of various types, they are "connect and forget applications". Mating cycle ratings in these applications become a non-issue. When we look at rated mating cycles for connectors ... I mean when we actually look at them ... it is amazing to us how low (or non-existent) most of the numbers actually are. As a product design engineer, I have gone through this search many times and ... well, let me just say that it was disappointing. Can you believe that some of the most expensive connectors I have looked at (some of them mil-spec) were only rated for 500 mating cycles?🤨 The worst of it is ... many, many do not tell you what they can do. This includes some of the ever present USB connectors that are everywhere!🙂

I am so glad that you found this helpful! Thank you! :-)

WOW! How did I miss *this* comment! :-/ "Free capacitor and/or diode" ,,,LOL! :-)

I have no idea how I missed this comment/question. YT obviously doesn't notify me about every comment. :-/ Now *there* is a very good and practical question! I actually haven't thought much about it. I go to the electrical supply store and buy one of those clamps that is specifically designed to attach to a ground rod (www.homedepot.com/catalog/productImages/1000/c0/c0466da9-4238-46d3-a35d-202bd42d6544_1000.jpg) and use this. Instead of the ground rod, it is the tower leg. :-)