Budget Bliss? A $35 Antenna Tuner for Ham Radio: QRP Z-Match

[@Swamp-Fox]

If I am not mistaken, those resistors are an absorptive bridge switched in line in the Tune position so your transmitter sees a ~50 ohm load while tuning up. Nice little tuner for the money!

[@TheSmokinApe]

That would make sense, thanks for watching SF 👍

[@rjy8960]

@@TheSmokinApe I was of the impression that the Z-Match allows you to present a nominal 50R match to a transmitter during the tune cycle with the "Tune" position. I'm considering getting one for my QDX transceiver which are prone to letting the magic smoke out of the PA stage when operating into anything over an SWR of 1.5:1. I guess that changes if you start listening to the "SWR doesn't matter, dude....so long as you have at least 3dB loss in your coax" brigade........

[@tomking8597]

The circuit that it uses for tuning is called a Wheatstone Bridge. Where one leg is the antenna and tuner. The other 3 are 50ohm resistors. When the antenna is tuned to 50 ohms (100x2 in parallel )the 2 legs are equal and no current is through the led. Also the 10watts is when you are tuning because of the parallel signal paths. I just received mine and I haven’t had a chance to to try it yet.

[@TheSmokinApe]

Thanks for that info Tom 👍

[@tinwhiskerSC]

I bought one of those a few months ago for QRP POTA work. It is very easy to use and works well. The best part is that your radio will never see anything greater than a 2:1 SWR. Lately I've really fallen in love with manual tuners over automatic after I had an automatic malfunction and damage a little QRP radio with infinite SWR.

[@TheSmokinApe]

Thanks TW, glad you liked it 👍

[@TerminalElement]

This tuner is amazing! I have used it to tune extremely bad antennas with atrocious SWR. I've even tuned a 2 meter antenna - with an SWR of over 20:1 - for use on 40 meter with this tuner! It takes a little getting used to, but with a little practice, tuning is quick enough. Thank you for making this video!

[@TheSmokinApe]

@@TerminalElement glad you liked the video TE, thanks for the comment 👍

[@KeepEvery1Guessing]

The tuning bridge is there to protect the transmitter from high SWR before the tuner has been adjusted. It's action changes the SWR from what is seen at the input to the tuner parts, so, in tune mode the SWR indication on the rig isn't relevant. You have to take the bridge out by switch8ng to work/operate mode to be able to see on the radio how good a job dimming the LED did at matching the load. (If the resistor to ground isn't close to 50 ohms,, or if the other two resistors aren't close to each other if value, the match will be wrong. I believe that they are all 51ohms, but with what tolerance?) And if you value your finals, NEVER switch between work and operate with the carrier on.

[@TheSmokinApe]

Thanks for the info 👍

[@DominicMazoch]

The good thing about POTA is we are getting great QRP and FD stuff.

[@TheSmokinApe]

That is true, thanks for watching Dominic 👍

[@K4AX]

I put this little sucker inline today with a G106 to play around, as the G106 has no SWR indication built in. Worked like a champ! tunes my balance line 160m antenna on all bands, 160 to 10. haven't tried 6m yet but ill get around to it.

[@TheSmokinApe]

@@K4AX that’s awesome man!

[@nevellgreenough404]

About that LED glowing in the "work" (operate) setting: The LED is only supposed to be active in the TUNE mode. Stray capacitance in the switches may (will) cause it to glow in the operate mode. Call it a "feature" RF output indicator. Nice review! --72's, N2GX

[@TheSmokinApe]

Haha, thanks Nevel 👍

[@richysradioroom]

This is Based on a design that's been around for a long time. To build this on your own it would cost about $30 for parts and shipping. So this item is a very fair price. I recently built one from a kit that has a plastic case.

[@TheSmokinApe]

Hey Richy, I saw a kit online but it was around 70$

[@wkjagt]

Awesome video explaining this little tuner. One thing I don't understand, looking at the schematic, in work mode, the tune components (with the LED etc) are completely disconnected, but when you later test the tuner connected to the G90, the LED comes on in work mode as well. Or maybe the tuner isn't exactly like the schematic?

[@TheSmokinApe]

@@wkjagt I was a little confused by that as well 🤷

[@Siskiyous6]

QRP guys have a similar kit, I learned from that about LEDs being a one direction appliance.

[@TheSmokinApe]

Hey LC, I think I looked at that one way back.

[@robertmeyer4744]

Interesting tuner. I have not used a Z match yet . I have used Pi tuner and LC matching as the T match. Not the greatest method of tuning led. A directional coupler will give better SWR but will add cost. You could test that tuner for loss with that VNA . 73

[@TheSmokinApe]

Hey Robert, I’m thinking about building one now 👍

[@KO4VNX]

Why do you keep showing me things that make me want to buy them? You have done it again!

[@TheSmokinApe]

Sorry, didn’t mean to! Thanks for watching 👍

[@jameski5oeb668]

He is good that way!

[@Tom-n5tti]

I love mine... works great with my QMX!!

[@fotoblanco]

same here. works great with my 817. LED works and at dimmest, the radio shows 1.5 or less.

[@TheSmokinApe]

I didn’t know how popular these were.

[@georgestein7484]

I am thinking about a simple tuner like this to use with my Perseus and a Wellbrook (amplified) loop. I like in an area with qrm and want to be able to hopefully get a couple extra S units on receive by adjusting the impedance to 50 ohms based on watching the SDR 's S meter and trying to peak the signal. Any comments and suggestions are most welcome. Regards, George Redmond, Oregon

[@germanjohn5626]

The T match is popular but has a big draw back, it is in essence a high pass filter passing all harmonics and higher frequency spurious. Looking at the schematic, the resistors on the input actually form a crude return loss bridge generating the lowest voltage across the LED for the best SWR.

[@TheSmokinApe]

I’d agree with you one the High Pass, thanks for watching GJ 👍

[@WECB640]

@@TheSmokinApe The T-type tuner shown is also a "high pass" design. Very few companies make a Pi network tuner or a low pass T tuner. Modern radios are very clean of harmonics, unlike transmitters of 40+ years ago where a low pass tuner would be a very good idea to stay in FCC compliance.

[@TheSmokinApe]

Thanks Hollywood 👍

[@germanjohn5626]

@@WECB640 The tuner shown is a Z-match i.e. a tuned transformer and acts like a band pass filter.

[@WECB640]

@@germanjohn5626 Yes, I know. The T-tuner (high pass) I'm referring to is shown at 3:50 Sorry for any confusion. 73 OM

[@BurtonChristmasLites]

So with this Z match, can you adjust for the most noise and it then be close? Ignoring the LED. As your did not work completely right at the end of the video. Thanks, Robert KD4YDC

[@TheSmokinApe]

Yeah, it’s a tuned circuit so the premise is the same 👍

[@kevin-pk6hd]

Got one because i couldn't buy parts for the 22$ delivered when it was on sale 😂

[@TheSmokinApe]

Haha, sounds like you have a project planned 👍

[@Thump2030]

Nice little tuner.

[@TheSmokinApe]

Should be fun to mess with

[@don_n5skt]

Thanks Ape. That seems like a clever way to match. I don't think I have used a Z-Match. Are they any good for matching Ladder line or does it matter?

[@TheSmokinApe]

From what I read if my feeble memory serves me, Z-Match are somewhat popular with the open line folks. I’m pretty sure I saw a video where some ham modded this tuner specifically to use on open line 👍

[@LouiseBrooksBob]

Some tuners come with an internal 4:1 balun for use with ladder line.

[@TheSmokinApe]

And that’s a topic of hot debate 😮

[@georgestein7484]

Does this tuner work with a Wellbrook loop and SDR (Perseus, Airspy, etc) for receive only? I am just trying to gain a few S-units if possible.

[@TheSmokinApe]

I’m sorry, didn’t try rhat

[@NShellhopper]

I wonder how it compares to the built in G90 tuner?

[@TheSmokinApe]

The g90 tuner is hard to beat 🤷

[@a_american_]

I bought one of these a few months ago. My findings were the same as yours. I suspect the resistors in the tune circuit are the wrong resistance, but I never bothered to check. I just tune in work mode against the radios SWR meter. I use it with my 705 a lot and it tunes perfectly fine. I’ve ran it with 10 watts FT8/FT4 for hours and it hasn’t failed yet. They are so inexpensive I’m going to pick up a second as a spare. It packs perfectly into my POTA kit and I bring it all the time I go out and also use it at home.

[@TheSmokinApe]

I like the size and it seems good for QRP despite the Tune / Work switch 🤷

[@Tocsin-Bang]

The one I got, from Aliexpress, was so poor I'm planning on ripping it apart for the parts!

[@LouiseBrooksBob]

Maybe rebuild it better?

[@Tocsin-Bang]

@@LouiseBrooksBob that's possible, but right now I have to repair the PA stage of my truSDX, I'm gong back to my modified AT-100!

[@TheSmokinApe]

I’m sure you will figure out something to do with it 👍

[@DaDitDa]

The SWR tune light does not *appear* to function correctly because the applied signal's frequency is constantly changing during the G90's SWR sweep. Apply a single frequency signal for a single match point, and the light should function properly.

[@TheSmokinApe]

@@DaDitDa thanks for the info 👍

[@hazer72]

Void all the warranties! :D

[@TheSmokinApe]

Right

[@TrevHolland]

Near the end, you're talking about the SWR light being brighter when the SWR is lower. I wonder if that's because you're in WORK mode and not TUNE mode. 🤔

[@TheSmokinApe]

Could be 🤷

[@DafyddWalters]

I'm puzzled how the LED comes on *at all* when the Tune/Work switch is in Work mode. Unless I misunderstood the circuit schematic, I think the absorption bridge and reflected power indicator are meant to be completely bypassed in Work mode.

[@johnnorth9355]

Man with G90 needs a tuner ? Seriously for a QRP SDR these are a must if you don't use a resonant antenna. Most of the autotuners seem to not like below 5 watts ?

[@TheSmokinApe]

Hey John, thanks for watching 👍

[@Embarking-on-a-new-adventure]

So a cheaper version of the good old Emtech ZM-2 Antenna Tuner

[@TheSmokinApe]

That sounds about right

[@LouiseBrooksBob]

I can't find the ZM-2 in the UK.

[@DominicMazoch]

MFJ knock off?

[@TheSmokinApe]

It might be, I’m not familiar with an MFJ pocket Z-Match 🤷

[@germanjohn5626]

Nah, this schematic has appeared in ham radio literature long before MFJ. It's a very basic 100 year old design.

[@TheSmokinApe]

@@germanjohn5626 I believe

[@TheRealEtaoinShrdlu]

"especially", not "expecially". 😂😂😂

[@TheSmokinApe]

Is that how they say it in your mom’s basement?

[@Hank_W6IR]

Gee, for the price of 2 of these you got yourself a legal limit tuner. Maybe not quite as portable though.

[@TheSmokinApe]

I suppose I never looked at it that way 🤔 can’t wait for that one to get here 😮

[@MichaelLivesInIdaho]

1500W tuner for $70? Where?

[@TheSmokinApe]

TO. Grabbed me one at a hamfest yesterday 😮

[@jerryKB2GCG]

Sorry, yes cheap, but not adequate at all, it does not perform as advertised, which you proved yourself.

[@TheSmokinApe]

I don’t disagree with what you are saying BUT 1) it’s 35$ compared to the MFJ which is about 100$ and it seem you could correct or mod this with little effort AND 2) Is the tune feature really necessary?

[@karlmadsen3179]

Did you say go watch someone eat a cat on a video!? That will wreck my appetite, for sure. Hard pass on the tuner.

[@TheSmokinApe]

I though I said watch cat videos but you have me thinking about it, thanks for watching Karl 👍