The L-Match ATU - Easy to Build. Ham Radio
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- Опубликовано: 16 ноя 2023
- The L-Match is the basis of many commercial Antenna Matchers including the Auto ATU models. But it is also easy to build a basic one fore home or portable use. Peter G3OJV. describes just such a unit.
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I use 40 or 50 turns of 1mm wire spaced at the wires diameter on a 50mm former with around 360pf variable capacitor(s) for L and Pi matches. I have recently become aware of the Etsy supplier of capacitors, It will save me scouring benches at rallies!! I've been making atu's for 40years it was my first construction project. Great video supporting home construction, The essence of Amateur Radio. 73 de GØUSL
Peter, thank you for discussing the "L" match. This indeed is the basic design for which all matchers are based upon. Each tuner has their own strengths and weakness, but the basic L is by far the easiest to make and is the easiest to tune because there are only two components. It is also the easiest to understand. Matching units are becoming more expensive every day and I think we need a group build for HF "breadboard style", perhaps on a plastic cutting board.
Thank you also for displaying the complex impedance in the schematic. There is quite a bit of confusion when new hams discuss impedance and I'd like to see more discussion in the main where we use complex impedance just as an engineer would. This also simplifies and reinforces our lesson when it comes time to use a Smith Chart. 73 OM, keep up the great work. PS. I like the friends display on the wall in your kitchen. 👍
Thanks for sharing the info. 73 Peter.
I recommend making your own L match Peter, I actually used a variable capacitor taken off an old valve radio, I bought it at a rally for about £3, mine is for QRP 5watts, I'm told it's OK up to 25/30 watts with this capacitor I made the tapped inductor on a piece old 2 inch wide plastic pipe wired the coil tapping's to a rotary 10/12 position switch, works fantastically well ,used along with a 49:1 unun, it matches up very well indeed, like you I use a counterpoise ,L match is by far the easiest to build.
Paul
Great info Paul. Many thanks. 73 Peter
The idea of Ham Radio being a "hobby" is to teach others to actually build their haystack accessories such as antennas, antenna feeding devices, and test equipment. Buying "off the shelf" should be discouraged because buying already built stuff doesn't teach you anything. So, I have built antennas, antenna feeding stuff, and some shack accessories like antenna tuning devices, doing my own circuit boards for projects, and so on. Such building of things expands your knowledge and helps you understand how circuits actually work.
Remember some hams have issues that prevent them building gear.
Yes, that is what amateur radio was originally all about. All the first broadcast stations started by amateurs experimenting and developing the art. This is a primary reason the governments allow and license amateur radio practice. Looking at their original call signs, most had a number in them for their area as do present call signs. Most all radio engineers started out in ham radio. All my former mentors in commercial radio were licensed amateur radio operators, as well as commercially licensed engineers. Example, KDKA started as 8XK by experimenter Frank Conrad, before becoming KDKA, Pittsburg, Pa, USA.
@@larrybarnette4795 Yes, Larry, I started in Ham Radio, then went to college to get a BSEE at Rochester Institute of Technology, then got the Masters at Western Carolina U. in 1993. Was a Broadcast Engineer at WHAM, WCMF, WRFR, WCMF, and finally at WACQ. Then, the FCC deregulated the industry and suddenly the requirement for us Broadcast Engineers and bored (literally) operators were gone. Computers run the TV and Radio stations and roving "Engineers" fix the equipment for a price. The old days are gone forever. I still maintain that you must have the ability to assemble and repair your equipment to a point. Surface mount stuff is tricky at best, ruinous at worst, but you must try. Discrete component stuff you can do in the shack, tube electronics you can do in the shack, too. My Novice station still lives after 44 years, a National HRO receiver, and a Johnson Viking Valiant transmitter along with a Drake R4B/T4XB/MS-4/AC-4. All were not working when acquired, but under expert tutelage from my Elmer, I learned the value of repairing such equipment
Brilliant 👏
love it just love it, I think you have been to RADA. an OSCAR for you Peter.
Nice thought but just a bit of fun!
Great...always informative and entertaining as well.....😅
Glad you enjoyed it
Well done Pete, You could have acted in the carry on movies, Carry on up the Kiber, etc, wonderful stuff. lovely. Thanks.
Wow, thanks
OR - carrier up the cable HI
G4BTI
👍Thanks for video Peter. The timing is bizarre - I made an L-match a couple days ago for QRP/P EFHW. Hoping to get out and test it this weekend.
another really useful and interesting video Peter. I may be tempted to give this a go (these capacitors look very good too!). Thanks for sharing...oh, and your friend in the woolly hat made me laugh...
Nice to hear from you.
Very good 👍 Thank you
M0DSK
Thank you too!
Nice video Peter, the MFJ-16010 is probably the simplest off the shelf one. VK3YE another Peter, has made some amazing qrp dx contacts with his homemade L matchers. He has a good RUclips channel. 73 Steve MW0SAW
Many thanks for info Steve.
Many thanks!
73' de K4WRF
Thanks to you too.
I use a homemade L match with a reverse switch to swap input and output to get the other half of the impedance range.
Great.
😊 Loved the characters… Its an interesting thing building stuff… don’t think I would do it because I can break a ball bearing and with everything being built for us now most ham operators are not intrepid enough, well I’m not anyway.
73
Many thanks for your support.
Could it be used in line with the 9:1 unun?
Yes indeed.
Jam radio? :-) Could be sticky!
Yep.
I think I recall that women made these variable capacitors during the war... What about a 9:1 and a non-resonant length that is supposed to cover all the bands without a tuner... is that a thing? All the Best! 73 DE W8LV BILL
The 9:1 gets the VSWR down on some bands but normally requires the help o& a matcher.