Measure inductor Q with this - Part 1
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- Опубликовано: 6 фев 2025
- Measure inductor Q with an HF transmitter, a digital multimeter and a few other parts. Watch this video to learn how.
VK3ANJ simple Q meter www.armag.vk6u...
VK5BR Q meter www.ahars.au/v...
VK3XU Inductance Meter www.armag.vk6u...
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I love this stuff! I’m 84 now and have been an active builder, operator since 1955… This takes me back to my “roots “. My FT817 is just as well used… LOL! 73, AF6OM
Excellent video Peter 👍
That's a very useful bit of information thanks for sharing Peter 😊😊
A very useful tool. I have wound several of those types of tapped coil recycling mains electrical cable for loading coils for low frequency verticals, and you definitely want the highest Q you can get in that application.
Can't wait!
Nice test setup. I prefer the ring down method because you can see the results in the scope trace even before you know what the number value is.
I'm currently working on a universal coil winder so I can wind high Q coils for use in IF transformers. My thoughts are to use a dual conversion at 1700 kHz and 95 kHz.
Part 2, part 2!!!
Available soon!
Nice simple instrument to build and have at hand. Having the analog meter just to find the peak is usefull. Finding it with a digital is quite frustrating since is refreshing the everage measurement just every second or so and the setting of the cap is touchy. After peak found read the exact voltage on the digital one.
Having a bigger box you can add a cheap digital meter meter inside not requiring a separate instrument to carry with. In most cases even the cheap meters are accurate enaugh. Probably easier than trying to calibrate the analog to measure on wide range of voltages with required resolution.
Have used the same concept on a grid dip meter I've build in the past. Small analog meter to find the dip and cheap counter to read the frequency. This way was no need to bother with making a scale for the tuning knob. Years ago when frequency counters were not easy/small to make or cheap to buy, making a good scale for all the frequency ranges was the main challange.
73 Andrej - s57rw
Oh, yes, the ol' Q-anon meter, i remember now... I think that's the one they hooked me up to, with the electrodes, when I went to the Scientology office for a quick visit... I woke up in Mexico a few days later, but that's another story.
It will be amazing
Hey Peter
How does the capacitor and frequency you’re measuring with affect the Q measurements??
Measuring the same coil at different frequencies will be another test. I suppose the main value of a unit like this is being able to compare different coils at similar frequencies so you can pick the best.
@@vk3ye cheers
I picked up some alligator clip to SMA leads for the NanoVNA to do some tests on some coils, caps and filters. Haven’t had a chance to use them yet. Been too busy.
I really love this project, Parker. Thanks for sharing your presentation. Congratulations.
I admire your sincerity and dedication in homebrewing activities.
De VU2RZA
Could you use the Nano VNA to measure the Q of the inductor?
I see many pros and amateurs here on youtube claiming that the inductance and capacity vary with the frequency. I learned to measure inductances and capacity with a huge tube (valve) Q-meter, in late 80s. I also used a GDM, a RLC bridge, tools that I built myself. However, I learned and always knew that the inductance and capacity are a constand depending the constructive dimensions.
Am I wrong? If yes, what I am getting wrong? And if no, what others get wrong , maybe misunderstanding the inpedance?
Edit: If I remember correctly, Q=wL/R, if you can measure precisely L and R.
Yes, inductance generally remains approximately constant with frequency over typically a wide range, for air-core inductors and for inductors with ferrous cores as long as the core permeability remains constant. The permeability of some ferrous cores will change with frequency causing the inductance to change. Actually, the inductance of almost any inductor does decrease a little bit at quite low frequencies where the lack of skin effect allows the current to penetrate deeper into the conductor. At quite high frequencies that approach the self-resonant frequency of the inductor, the apparent measured inductance increases because the wire begins acting like a transmission line approaching a quarter wavelength where the capacitive susceptance of its self-capacitance offsets some of its inductive susceptance, thereby raising its overall reactance. This may be more than you wanted to know. 🙂
@@analog_guy Thanks for your reply. I know that, and also that a real inductance is not really only a inductance, it have some inter-turns capacity (there is where you have its resonant characteristic) and also its wire resistance (that vary with the frequency, by the skin effect).
But what I do not understand is that a 10uH inductor is measured with a digital modern LC meter and the values vary from 8uH to 14uH (as I saw in some videos) depending the frequency that tester uses to measure with from 100 Hz to 100 kHz. 10uH should be 10uH at 100Hz and 100kHz, right? Are those testers flawed, the measurement method or I am wrong? I mean I used 1-10uH inductances in RF-SW, I built them and measured with my GDM, Q-meter at home or with a RLC bridge at the radio-club at various frequencies and after doing the math, always I had the same result for the inductance value, maybe with some decimal point (100nH) difference, but not 5uH.
Or are the modern inductances so bad?
@@sebastian19745 About all I can say with any confidence about the 10 uH inductor is that any inductor with magnetic core (permeability greater than one) that has been optimized for a particular application will be “good” for that application but may behave strangely and appear “bad” when tested under different conditions. There is a wide range of magnetic core materials and they all exhibit nonlinear behavior as well as behavior that varies with frequency.
3dB bandwidth method.
.707..😊
I would want you to test and compare the Q of coils wound using ferrites and iron powder cores.
De VU2RZA