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Reviews Categories | Antenna Tuners | Hamware AT-402 Help

Reviews Summary for Hamware AT-402
Hamware AT-402 Reviews: 3 Average rating: 5.0/5 MSRP: $Euro 660,--
Description: REMOTE CONTROLED BALANCED antenna tuner.
Capable off matching 100/200 watts.
Matches Dipoles up from twice 5 Meters, Frequencies from 1.8 MHz to 30 MHz.
Optimum Usage of available Space for the Antenna.
No RF Ground (Counterweights, Radials, etc.
Low Impedance Coax Cable from Shack to Tuner.
Consequent symmetrical Ciquit Design to match complex Antenna Impedance. Balancing
is done at the Input Terminals where the Impedance is purely resistive when the Antenna is matched.
Outside unit is enclosed in a IP-65 weatherproof box.
Product is in production.
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HB9DOZ Rating: 5/5 Dec 31, 2004 08:06 Send this review to a friend
Remote controlled balanced antenna tuner  Time owned: 0 to 3 months
The AT-402 is a remote controlled balanced antenna tuner, available from Klaus Bemmerer (DJ2HW). A detailed description, including specs, schematics and specials features is given at http:// Briefly, it consists of a control-unit (with LCD display) linked by a 25-wire cable to the HF-unit, containing the balanced tuner. A total of 12 settings can be selected conveniently by a rotary switch. Programming is straightforward.

I have ordered the AT-402 as a kit (finished units are available, as well). It comes with a complete technical documentation, containing schematics, PCB layouts as well as assembly and operating instructions. Referring to the PCB layouts and parts list, the kit is easy to build and works great. Klaus Bemmerer was very helpful and quick answering my questions and coming up with suggestions how to tackle to two minor problems I had building the unit (I had C14/15 and C9/10) installed incorrectly).

The AT-402 works perfectly. It's possible to tune a 2 x 6 m dipole (with a 1 m 450 ohm feed line) to a SWR of 1:1 between 1.8 and 28 MHz. Some care, however, needs to be taken at short antenna lengths. A minimum antenna length of 2 x lambda/8 at 100 W (2 x lambda/4 at 200 W) is recommended (e.g. 2 x 20 m with 100 W at 1.8 MHz).
DK3UZ Rating: 5/5 Aug 30, 2004 08:22 Send this review to a friend
What the world has been waiting for!  Time owned: 6 to 12 months
Often radio amateurs are kept from using ladder line to feed their antennas because open wire feeders need to stay clear of other, especially metal, objects. Ladder line also doesn't take too kindly to being buried under the lawn, as I would have had to do at my QTH. So I had to be satisfied with coaxial cable and the resultant additional loss from mismatch.

Then the AT-402 came to the rescue! Under the turf it's still coax, now accompanied by a DB25-connector terminated control cable running between the coupler at the pole's base and the remote control unit in the shack. Up the pole now runs open wire line to my Guywire Pyramid's summit.

After successful installation a further hour with a noise bridge was needed in the shack, twiddling knobs on the control unit, in order to find the correct C-L-C (symmetrical PI-filter) settings for the coupler and store them in one of the provided twelve memory locations. Because of a backup AA-cell in the control unit, values written to memory stay put when the supply voltage (13.7v) fails. The AA-cell's lifetime is primarily determined by self-discharge, so it should last for many years. It can't hurt though, to keep a hardcopy of the settings. Anyway, setting up the coupler went fast and easy, it probably could have been done with a TX and a VSWR meter instead of an RX and a noise bridge, albeit at the cost of plenty of QRM.

Only complaint I have is that when I acquired the AT-402, it wasn't available yet as a kit...
KJ6ETL Rating: 5/5 Feb 13, 2002 19:43 Send this review to a friend
Perfect solution !  Time owned: 0 to 3 months
Since the famous Johnson matchbox no other manufacturer bothered to build a matching system that is truly balanced. So I ended up home brewing my own. Since my shack is small and has to be very tidy. I had a big problem by getting the open feeder into the house. On top off that I lacked the skills to build a decent coupler that could live up to the limitations off my shack?.

I found this REMOTE CONTROLED BALANCED TUNER by sheer chance on the internet. Since it would solve all my troubles in one hit. I ordered it straight away.

The (German) manufacturer is very pleasant to deal with and soon I had the AT-402 in my hands.
Both units are very well build.

The only thing that I have to arrange myself is the control cable. Which is the same a serial printercable. According to the manufacturer one can run up to 30mtrs off control cable (if you use 0,14 mm cables).

At this moment the tuner part is still inside my shack connected to the open feedline. As soon as the weather is ok I will bring it outside where it belongs :-)

The controlbox has 12 memory settings (this is not a automatic tuner!) witch are very easy to aces. Just tune the antenna, select one off the 12 memory's and push each control knob. If you return to a memory position and you want to re-tune. Just flip the switch to "tune" and do it. The pre-set position remains upon the moment you "enter" a new setting.

The unit can handle 100 watts while tuning and 200 watts when a good match is archived. It has no swr meter inside and runs on the regular 13,8 Volts.

So far I am very pleased with the results.


Roger (pa1zz)

Maastricht, the Netherlands

BTW if you go the website you will find under de German flag an additional site with even the complete circuit

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