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Reviews Categories | Antenna Tuners/Matching Networks | ZM-4 QRP ATU Kit by Help

Reviews Summary for ZM-4 QRP ATU Kit by
ZM-4 QRP ATU Kit by Reviews: 3 Average rating: 4.7/5 MSRP: $87
Description: The ZM-4 is a QRP Z-Match ATU Kit. Housed in a rugged extruded aluminium case with a large torroid and PCB.

No additional parts to buy - the kit includes everything bar the tools and time.

Balanced and Unbalanced output from Banana Jacks and BNC.

Matches high and low Z antennas from 160m to 10m.

Built in Wheatstone Bridge for SWR sensing.
Product is not in production.
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HG0WH Rating: 4/5 Jan 15, 2018 09:06 Send this review to a friend
Very compact, can be strapped on the Yaesu FT 817  Time owned: 0 to 3 months
When I put the tuner together, it turned out that I made a mistake while soldering the LED: it was soldered to the wrong hole (well, I don't quite understand why was there a hole at all :-) While trying to find the failure I contacted the support without any response in 3 days. They were only responding after opening a case at PayPal. Well, this was an unexpected experience anyway.

I've been able to tune more endfed antennas to about 1.0-1.1 SWR (measured on the Yaesu FT 817ND display, and also on external SWR meter). In the beginning I was surprised why is the feedback LED showing a wrong SWR minimum above 14 MHz (up to 10 meters). Sometimes it was not even possible to use the "Tuning" setting for tuning the antenna to find a nearly good SWR, because the LED was dim throughout the whole range.

It turned out, that this is basically the problem of the feedback circuit. The small ferrit ring is too close to the big one, so they interfere. This is the reason why the tuning LED lights during normal transmission, when it should not.

So above 14 MHz the tuning setting is nonsense, because using the radio's swr or power meter gives the right value, not the tuner's LED. While the Yaesu FT 817 ND (or plain 817) is protected from high SWR, this is not a problem for me, but for more simple radios this tuner won't work in the higher bands - at least tuning with the SWR protection ON gives a false feedback.

Yet I give 4 points instead of 3 because DL7NIK Nikolai was so kind to drill the front and back plate for me, so I did not need to do it myself. Also, the tuner is capable of what it is designed for: tuning between the 160 and 10m bands.
PE1FJN Rating: 5/5 Dec 8, 2012 08:29 Send this review to a friend
FINE QRP tunere  Time owned: more than 12 months
Fine KIT, works good with QRP equipment, and has the advantage of additional filtering, off loading RF front end from strong out band signals.

Also the SWR bridge is nice, securing good VSWR during tuning and antenna experiments.

I use it with my T1380/T1340 and K1 with pleasure.

M0JMO Rating: 5/5 Mar 16, 2010 07:19 Send this review to a friend
Works Great for QRP /P  Time owned: 0 to 3 months
I needed a small, light ATU for portable use with my new FT-817.

I owned an Emtech ZM-2 when I last had an 817 which worked well, however I was always a little worried about how well it would stand up to being rattled about when /P as there isn't a PCB inside to keep all the components stable.

This time, I did some more research and found the ZM-4, which is a German evolution of the ZM-2.

The kit arrived quickly to the UK and went together in a few hours.

Drilling the case was a bit tricky for me as I'm notoriously bad at this sort of thing, however it wasn't too bad and I made no mistakes!

The PCB is nice to work on and the large toroid is fairly easy to wind, even though there are multiple windings to deal with.

Instructions are good and are provided in German and English.

I've found that this ATU has tuned everything I've tried it on so far! Typical for a Z-Match I suppose, but it's nice to have the flexibility to tune whatever you have handy.

I'm really happy to have bought and built this kit.

Josh de M0JMO

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