LDG RT-100 Remote ATU Review

I have 2 LDG ATUs now, the Z-100 Plus and the other day I ordered the RT-100/RC-100 combo from Martin Lynch. I was fed up with having to press the CS button on the FT-450D that I had configured to send a 5 watt carrier to get the Z-100 Plus to tune! I have never found a way of configuring Ham Radio Deluxe to "press" the CS button. There isn't a CAT command defined by Yaesu for it.

On to the remote tuner.

The RC-100 Controller and the RT-100 Tuner

The construction of the ABS box is top notch although I have not glanced inside (no need). I did find plenty of pictures on the internet for it though.

Internal view of the circuitry

All connections and the cover have gaskets to keep the weather out.  All connections were covered with self amalgamating tape and it was ready to be hung. I hung mine from the support rigging holding my wire antenna up in the trees using a few tie wraps. The connectors are then on the lower side of the enclosure.

RT-100 ATU (on the left) hanging from the antenna support structure.
The other box (on the right) is the 9:1 UNUN
The ATU and UNUN are connected with a 1m long MIL spec coax/PL259 with
ferrite beads on both ends of the coax. There is also a ground connection from the
grounding lug on the ATU to the grounded side of the UNUN. This
runs to a copper earthing spike located at the base of the tree.

There is a note in the instructions saying the antenna cable feeding DC and RF to the tuner must not be grounded. This could cause damage to the ATU and controller so I made sure that the earth connection was run to the grounded connection of the UNUN.

Operation

In the shack the supplied RC-100 controller goes between the radio (or after the SWR meter if you have one) and the feed line. This is plugged into the shack power supply and in turn feeds power via the aerial coax to the control box outside. The controller works in fully automatic mode normally and when you switch to a new frequency can take up to 10 seconds to match the antenna. However this is then stored in one of the 2000 memories and next time you tune to that frequency the ATU switches in a few milliseconds. You don't need to press any tune up buttons on the rig as keying the transmitter is enough when working in fully automatic mode. If however you are finding it difficult to tune the RC-100 has a tune button to force the ATU into searching for a good match. This operates by keying the transmitter with a steady carrier and then holding down the RC-100 TUNE button for more than one second.

There is also a power button on the RC-100 controller to remove power from the ATU. The ATU has latching relays and always remembers the last settings made. All in all a very good ATU for digital modes to 30 watts and SSB/CW modes to 100W. This is fine for most HF transceivers.

Results

In use my 80m to 6m 9:1 UNUN fed wire could still not tune at all on 80m but all the other bands from 5MHz up to 6m tuned perfectly every time.
I did notice that the amount of power the rig put out on my external power meter was a few points higher than without the RT-100 in circuit.I was also able to work stations I had heard before but never been able to contact.

Another very impressive product from LDG.

The RC-100/RT-100 is available from many sources and Martin Lynch currently (March 2016) have it on sale for £209.99 + shipping.