Wednesday 30 October 2019



When using my portable radio (ICOM IC-7300) during a Field Day Event I need an autotuner to supplement the in-built tuner which only matches antennas with an SWR of less than 3:1.  I could of course use my diminutive Z-817, but that can only handle around 20W which would be no good if one of my radio-club colleagues wanted to sit at the mic.  So the answer was to find a small, light ATU and a quick search resulted in me choosing the LDG Z100PLUS.

It's similar to my LDG Z817 and shares the same "Zero Current" technology which means that in standby-mode there is virtually zero current draw - which is why there's no ON/OFF switch. The unit is powered from internal batteries (which should last for approximately one year) but can also be powered (and controlled) by the radio if you purchase the appropriate lead.

With the control lead fitted, the unit takes its power from the radio (the IC-7300 Molex connector in my case) and also permits the radio's "TUNE" button to be used instead of the LDG's. 

The Z100PLUS can handle 125W which makes it perfect for most of today's popular rigs. It will also handle about 30W in Digital mode. It has 2000 memories for near-instant tuning of previously tuned frequencies.

The LDG Z100PLUS interfaces with the QRP ICOM IC-705 superbly, using a regular 3.5mm jack to jack stereo lead, so it's a great option for that too. Makes a nice change from having to buy expensive interface leads (are you listening Yaesu?). I think you can also program one of the 705's front-panel buttons to act as a TUNE button. For the IC-7300 you’ll need a 3.5mm to Molex interface lead available from TechnoFix

I see Waters & Stanton posted a video on 14 Aug 2021  virtually claiming that this ATU was designed specifically for the 705 but of course it's not - the Z-100PLUS was in production way before the 705 hit the shelves.

The ATU weighs 570g. Download the manual here.

Since writing this post, I've also bought an Elecraft T1 for portable use with my IC-705. The LDG is much cheaper and performs extremely well in terms of what it will tune-up. It's a great little ATU and I recommend it highly!

Thanks for visiting - please take a minute to leave a comment below 

73, Tom, M7MCQ.

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