End Fed Half Wave Antenna Tuner: Part 1 - Initial Build
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- Опубліковано 9 січ 2025
- Video looking at a simple multi-band end fed half wave antenna tuner. The idea was to use one 80m EFHW antenna for the 80m, 40m and 20m Please note that the tuner in this video is not the final verison and will be repacked. Part 2 will show that.
This design is much better than trying to use broadband transformers with extreme ratios. The only caveat I would add is that the resonating capacitor needs to be able to operate at high voltages if energized with more than a few watts.
Resonant transformers are indeed the best tuners.
Many thanks...
Great video. Exactly what I look for and find most useful. Which is an explanation of the circuit (or theory), a demo or a lab test and then a demonstration in the field. Thanks Charlie & 73 2E0FXZ
Glad it was helpful Stephen.
73
Charlie ZL2CTM
I'm slowly catching up with your videos and I'm happy I got to this one... as I was just about to prepare building the older tuner version... so I guess plans changed hahaha. I just don't have the meter so I will try to use the LED version instead. 73 and thank you for sharing.
No problems. I tend to try new things and the old versions go on the shelf, or are pulled apart and recycled.
I do the same all the time...))) 73
Hello Charlie, Very nice video. I would like to test your antenna. Please could you give me more details how to realize the toroid T68-6 ? Tanks a lot! 73's. Stephane.
Hi Charlie
Can you explain the selection and preparation of the polyvaricon. I have some that dont look like the one you used, and it appears that you've shorted sections together.
Cheers
Great video Charlie! I was thinking of playing with a tuner project not too long ago. this will help me make up my mind.
Go for it Curt. The hardest part for me here was finding a suitable tuning capacitor. The new commercial ones are only 160pF, which would have needed additional parallel capacitance. No biggy, just more parts.
@@CharlieMorrisZL2CTM I have had to change my mind on many projects because of the variable capacitor they are so expensive and hard to find. I believe that is how I found your channel with the Si5351. lol
Hi Charlie, as always a great video I used the same circuit in one I built some time ago but this video has encouraged me to rebuild it, also really enjoyed the mini tutorial on using a VNA :-) . I'm thinking of building a top band receiver only using an si5351
etc, fingers crossed it may be your next video, thanks and 73 Rick G4KRF.
Cheers Rick. I will build a higher band rig at some stage. I'll have to see how active they are in New Zealand.
@@CharlieMorrisZL2CTM Thanks Charlie, I think, as I haven't built anything for a long time or as small, I'll start with the si5351 and arduino board from your last video, at least then I'm making a start :-)
Excellent video Charlie! 73 and subscribed!
Hi Tim. I'm glad you found it useful. It's certainly worked well for me.
Didn't quite follow that through, but it might click when i see the completed version, I hope anyway. Looks as it it might be a handy bit of kit.
Thanks Bob. I should have the final completed in the next day or so.
@@CharlieMorrisZL2CTM Excellent, maybe it will make sense to me when I see it built. If not i might ask, if that is ok?
Nice project! What about automatize this like use servos and relays for switching and tuning and small mcu for control and sensing via AD converter. (idea for further improvement/project )
An automatic ATU is still on the future build list. It will bubble to the surface at some stage :0)
Nice video!
May I use your tuner on 30m-band and wire 8m between my window 5flor_house and tree?
Thanks.
Not sure Gena. I will try and do a 30m test with 8m of wire during part 2.
@@CharlieMorrisZL2CTM So good!
I think, next Part_2 will be very interesting also.
Very cool. I have been using a cheap tuner from ebay. ($35 auto tuner) for use with antennas i set up. I might try making a variant of this for my EFHW (which get 2 bands with out a tuner and only slightly needs one on the third) because it would be easier to take a passive tuner with for POTA then my auto tuner.
Sounds good. I might see how this goes for 30m. Might have to add some series capacitance. We'll see.
@@CharlieMorrisZL2CTM i also just realized your using this in place of the 49:1 / 60 something to 1.
Nice work Charlie. Did you try 30m? Not sure if you are allowed 60m, but both bands should be in the range of the tuned circuit. I did something similar last year but used an LED for the SWR 'meter'. I also found a design from a DL ham that used three two diodes to show low and no SWR, which was neat. Could you say why you selected the wire length and how much counterpoise you added in part 2? Thanks for sharing.
Hi Steve. No I didn't try 30m, but will once the final ATU is built. I'll also mention the antenna and counterpoise lengths.
Really enjoyed the video Charlie; where did you get the nice little meter from? Was it in the junk box or can they be bought somewhere?
Look forward to the follow up video!
Chris, G0VOE, Somerset UK.
Hi Chris. That was a junk box meter Chris. Sorry about that. The final version is built. I'll set up the antenna tomorrow and confirm it still works.
Charlie, you just gave me a good idea. I was using header pins between my boards on my radio build and find them pretty weak. I attached them to small coax or just wire for audio and control signals. but after watching this video I remembered the RCA plugs like you used in this project are good for HF signals as well. I checked out Aliexpress and found the board mounted sockets 10 for US $1 and they have very cheap cables as well. I think I'm going to try those to get my project more sturdy when plugging things in and out of the circuit. have you had any thoughts on this or are you going to stick with soldering the wires?
Sounds good. I have had no problems with these, noting that I typically work 20m and below and at QRP.
Charlie, Is the value of the resistor 2K5 or so?
It was a 5k resistor Alex.
wow mr tuner smile