#292
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- เผยแพร่เมื่อ 23 ธ.ค. 2024
- This video shows the assembly, design and operation of the QRPGuys Multi-Z QRP antenna tuner. This is a very nice little unit that is perfect for low-power / QRP operation in the field where lightweight and small size are important. It will operate from 40m to the 10m band. It features a built-in SWR indicator making is easy to use with transmitters that don't have an SWR meter. The tuner can be configured to tune coax fed antennas, as well as random wire and balanced feedline. Great little tuner kit. More information can be found on their website for the product:
Multi-Z tuner page: qrpguys.com/mu...
Main homepage for QRP-Guys: qrpguys.com
Very - Very well done video and description of the circuit. In the middle of building a different unit and actually this one looks like it would have been a better choice....
I actually like my Emtech ZM-2 better than this one, so I recently gave this to a friend.
Explained very well, I am construcing the same Z match from scratch for a start without the bridge good results so far.
I like the caliper lead bending technique. I’ll have to try that.
Why didn't I think of that?
Yea, that is clever. Could be used for other component leads.
It is a great idea on the face of it, but only with one of those 10 dollar plastic jobs. I used to see folks using their calipers as scratch gauges at work. Hmmm... I would not subhect any of my calipers to such lateral forces and continue to expect any ultimate accuracy. It's an abuse of a measuring instrument. In the context of the video though, it's another great "why didn't I think of that". Still a massive thumbs up for this and the other videos from this channel.
For those for looking for the caliper part, it happens at 3:55
Thanks for posting this. The one I ordered came in a day early. Im looking forward to building it. The only part im concerned about is getting the feont board mounted right.
I have one of their antenna circuits and it has a very similar circuit to this tuner. The instructions are great and it's easy to build.
Cool little tuner Alan! I'll have to get one. I wonder if anyone 3-D prints a case for this? Thanks for walking us through the circuit and explaining each sections function. I love it when you do that as I learn a lot! 73!
I built one , but couldn’t get it to work correctly. I measured the ohms in the 3 51 ohm resistors. Found one to be 51 ohms, but the other two only measured around 25 ohms each. Contacted the vendor for replacements. Will see what happens after I get them. Great video and explanation of the circuit.
Another first rate video. Holds my attention right to the end even though I'm not going to build it. Numerous good tips too. +1.
Love the written instructions. Reminds me of the old Heathkit kits.
i like this tuner, but am quite happy with the much simpler sota tuner (and the older BLT+) because of the enclosures... what's really good about your video is the circuit explanation, especially about the Tayloe indicator - so tks!
Great video. Just built one of these for use with the Icom 705 I have on order. Really like how you walked through the schematic, very helpful to a novice like me.
This video was worth it just for how you bent the LED.
I used to love QRP on field day night shifts in the Arizona desert. June is always so hot here
I just built this tuner with the aid of your video. Works great with my 20 meter MFJ cub. Thanks for such an informative video,de KD3D.
Thanks for the excellent video. I especially liked the theory portion. (And I seldom say that.)
The lead bending trick is awesome. Neat, simple SWR indicator circuit. I like it! Thanks for sharing.
Thank you for explaining the tuning circuit. I have a couple of their kits, and a 4S tuner as well. This seems to be a common circuit found in all of the kits I’ve assembled so far.
Thanks for this and your review of the EM-2. Both might benefit from larger knobs. I opted for the ZM-2, since I wanted a case. I like QRP Guys gear, but planning to use them outdoors, I need something with a case.
This is a good overview and the tuner is about half the price of the similar MFJ QRP tuner which lacks the SWR indicator.
just finished building mine. Thanks Alan.
Nice kit build Alan...I love PC board case construction, especially when you consider the skyrocketing cost of enclosures nowadays (hint: you can do a lot with the old PC switch boxes and metal hard drive enclosures which can usually be had very inexpensively). 73 - Dino KL0S
@w2aew
I have a question...
The conventional ratio for matching a transmitter output to an untuned end-fed wire is 3:1 winding ratio to produce a 9:1 (50 Ohms to 450 Ohms) impedance transformation, yet the winding ratio for this transformer is 16:12, which is going the wrong way. Even if I'm misunderstanding the circuit and it's really a double 8:12, that's still only 1.5: 1 winding ratio for a Z match of 2.25:1. The low impedance side is 16:6, which seems equally wrong. What am I missing here? Is there some phenomenon that magically makes the primary a 50 Ohm load to the transmitter? Or does it rely on transforming the impedance of the secondary circuit (transformer secondary and antenna) to generate that effective impedance?
Backing up, and sharing what I think I know about this... C3 and T1 primary form a parallel resonant LC circuit, which has its highest impedance (and therefore voltage into the transformer primary) at resonance. Conversely, C2 and T1 form a series resonant LC circuit which has minimum impedance at resonance - again, transferring the maximum energy to the transformer. All that makes total sense... but the ratios? I'm scratching my head.
Pretty cool kit. Thanks Alan.
Could anyone explain the significance of the center tap on the primary? All my Google results only deal with a tap on the secondary. Thanks
Thanks for the video as I am looking at getting one ! Has anyone fabricated a case or box for it?
Well, saved me some $$ - from their site - Fall recharge… QRPGuys will not be shipping product from now and until most of October. We will only be providing e-mail support, and answering inquiries.
Who in the heck would give this a thumbs down? Very helpful video, thx!
very nice job and kit!!
what a great little unit, one day I'll get into qrp opps
nice video, well presented!
Very neat video. I'm posting it on my ham radio fb group. Excellent explanation of the Z-match design. But what's the "Heat it inside" sticker on top of your FT-817? Curious.
It is "Hear-It" - a DSP noise reduction module: www.eham.net/reviews/detail/3626
This may be a question I should just Google, but I'll throw it out there anyway - is there an assembled version of this, or a commercial product that does that same thing? I am not that confident in my soldering ability.
This one is a Z-Match, works very well, and is available as a pre-built unit or a kit: steadynet.com/emtech/zm2-prebuilt-bnc-connectors
@@w2aew Thanks! Next question - this doesn't handle UHF?
And, yes I see they have UHF models, but what I mean is if you look in the description for them, it says "The ZM-2 will tune all bands from 80 to 10 meters."
@@arsbadmojo there are not UHF models. There are models with UHF connectors, which is a terrible name for the SO-239 connector because it is not a good connector for uhf operation.
@@arsbadmojo no, it is for Hf only
Any reason to use/make an auto-transformer instead of just two windings on a regular transformer? - 9:35
For the amount of wire required it would seem simpler and easier to use two windings.
Excellent project
Hi There, greeting from UK!
(Apart from the 80m band) How does this kit compare with the Emtech one in terms of ease of build and components quality?
Thanks for sharing
I found that the Emtech can tune a wider range, mainly due to the additional capacitors that can be switched in. This one is easier to build because there is a circuit board. Both are of similar quality.
Thanks Alan for another great video!
It doesnt have swr meter, Its an swr indicator more then anything else.
Good Video :)
10:59 - With it in "tune" mode why will the radio never see _"more than 2:1 SWR"_ ?
Because in the worst case (high impedance looking into the tuner), the bridge will present a 100ohm load to the transmitter, which is a 2:1 SWR.
What length of wire would be best for 40-10 meters?
What are some good projects as an intro to RF electronics? I find the "black magic voodoo" to be intriguing, but it would be nice to test the waters before taking the (rather expensive) plunge.
1. Build a 'crystal' radio which most often uses a germanium diode instead of a crystal. Only a few parts and some ingenuity required. There are loads of plans on the interwebs. You will learn the most basic principles of what RF is and how to 'turn it into' an audio signal.
2. Get an inexpensive FM radio kit, look around for one with an explanatory leaflet. A lot of the kits use a component that looks like a transistor but isn't, it is a three leg IC with the radio circuit inside. But these kits are worth building when you are starting out because you will gain experience and familiarity with components and soldering.
@@tdumnxy Cheers, just what I was looking for. I have plenty of experience with electronics as a whole, but haven't done much with high frequency analog.
Ziferten store.qkits.com/radio-frequency.html , www.a1parts.com
QRP Guys make good stuff. They are off thru October so no ordering at the moment
I was sent a .01 instead of a .1 for C1..Do you think it is OK to use it or should I get the.1?
It’s not part of the tuned circuit, it’s part of the reverse power sense circuit and will work fine.
@@w2aew Thank you for the reply..I thought maybe it would effect the LED. I'll leave it in place.
Hi Alan! Would it be possible that you put together a course on circuit design from basics up to somewhere you are right now? I have been looking for something like this for a while. What you're doing here could never be learned from reading books, even if you read a million books. I find your language and style of teaching invaluable and I'm already learning a lot from your videos. I know that you're very generous but if you asked me to pay for that course, I certainly would, most probably many people would. Would you please think about it? Thank you!
I've been asked to write a book before, but I simply do not have the time. Full time job, family obligations, etc. - just no time to dedicate to such a project. Maybe when I retire....
Alright. For the time being, I'll find some resource on design and work through it. Would it be okay to ask design-related questions sometimes, probably not directly related to the posted videos? Thank you very much for the wonderful content!
@@JohnRaschedian..not to take anything away from Alan's excellent efforts, but if you search for K7QO on you tube, will find some magnificent videos on circuit theory in conjunction with respect to amateur receiver theory as well as several prominent traditional transcievers. While this is not 'ground up' design theory, it is a fairly decent reverse engineering of designs and will give you a decent introduction to the black arts.
@@warplanner8852 Thank you! I have already started with a similar approach. I'm excited to see where it takes me. Have a good day.
Hey, do you think it would be possible to replace the LED SWR indicator with a connector that went to a MicroVNA instead?
I'm not sure of the purpose. A VNA has its own RF source - so if you want to use it to assist in adjusting the tuner, simply connect it to tuner input, adjust the tuner as needed, then re-connect the radio to the tuner input.
@@w2aew So the purpose of the LED is to show SWR right? I instead want to show SWR on a VNA without disconnecting anything. Can I replace the LED SWR circuit with a connector that goes to my VNA?
@@nathanjames4242 The LED lights up due to the mismatch across the RF bridge that results from a non-50ohm load. The LED is configured with a series resistor (to limit the current) to see the voltage across the bridge. A VNA works differently. If you want to add a switch to use the VNA, you'd simply switch the RF input of the tuner to the VNA. The VNA would not use the bridge that is part of the LED-based SWR indicator.
Hello! Very interesting and educative video. I'm thinking of buying one for myself. I got one question though... Can I use a "Loop" wire with this tuner? Thank you!
I haven't tried it myself, but it should work fine.
Quick question. Can you tune for max noise then key up and be even closer?
Tuning for max noise will usually get you close, but will still usually need a little fine tuning to optimize it.
If I wanted to use a single wire with this tuner, would it be a resonant or nonresonant length?. Im not sure what a z match tuner is for. Thanks for your help. KG7CQG
It would likely be best to be a resonant length. An end fed antenna will have a high input impedance.
HI, Do you have modification, which will cover 80m band?
Will this tune random length whip antenna for 11m?
not for all random lengths
@@w2aew that was my thought too, past 3:1 I'd think it'll be impossible. I was given this question and really had nowhere to put it. thank you for validating my skepticism
KN4GEI
Is This a tuner for any mobile radio use in cars? eg. Motorola CM series.
It is for adjusting the input impedance of an antenna system for low power amateur radio (ham radio) applications between 7MHz and 30MHz operating frequencies.
Hi, nice vid, I have a question. Where can I buy this kit? :)
The link is in the video description.
Thank You
Thanks for sharing! Cheers, Dave - KU9L
Two questions. You mentioned that when the LED is extinguished, the transceiver will see a perfect 50 ohm load. That doesn't correct the antennas impedance, correct? The tuner is there to protect the transceiver only?
Correct, when the LED is extinguished, the "tuner" is adjusted so that it presents a 50 ohm load to the transmitter. It basically does an impedance transformation from the complex impedance seen at the input of the feedline. It does not "tune" the antenna or change the SWR on the feedline - but it does allow the transmitter to deliver full power to the complete "tuned" antenna system, which includes the tuner, feedline and antenna. There will be losses in the feedline and the tuner.
@@w2aew
Very helpful explanation. I guess, it would be better to get the antenna tuned as perfectly as possible.
For feedlines with loss (like coax), this is always best. For low-loss like twin lead, it doesn't matter so much. For portable/temporary operating, often it isn't practical to physically adjust/tune the antenna in use, so an external matching circuit like this is helpful.
@@w2aew
Cool. I always enjoy your videos, they are very thorough. I even built your RF sampler/demodulator.
Good...
$ ?
Perfect
I'm looking for a QRP SWR and power meter. It is mainly for a WSPR transmitter so max power at full scale of maybe 0.5W. Any recommendations?
I would like to leave it in circuit continuously unlike this SWR indicator.
Nice
Shame he didn't ask the PCB fab to leave off the PCB id code off the board.
Unfortunately, the expensive postage stops me from buying anything from them! Which is a shame because the stuff they make is cool!
Yes, shipping from the UK to the US is so high I'm left wondering if the Queen herself delivers kits from there in a Rolls Royce. I suspect the same is true in the other direction. These kit suppliers might want to set up stores in various countries, ship bulk, and benefit from domestic postal rates.
Can bigger caps thicker wire be used and a 240 torroid be used to make a 100watt version using the same schematic?.
Yes, caps rated for higher voltage, and a larger toroidal would be needed for higher power
hook it up to a vna
Hot dog, # 1 view , on stand by for big blow coming soon. Dave, W4GSM