I have been trying a couple external Tuners with my IC-7300 transceiver, with mixed results. They actually both worked, but operation is a little confusing. The tuners I have tried so far are:
- Elecraft KAT-500
- LDG Electronics IT-100
The Elecraft Tuner is made for the K3-line but Elecraft has also made sure that it can be used with other Rigs. The LDG IT-100 is specifically made to be compatible with ICOM radios that use the standard 4-pin antenna tuner interface. This is a great interface, allowing flexibility to use a tuner with many Icom rigs. I do HATE the 4-pin connector that connects to the radio. It is a friction-mounted connector (no keys or tabs to press), but it is extremely hard to remove. Every time I remove it, I am afraid I am going to damage the radio. if you have to remove it from the rear of a radio that is on your desk, reaching over the back of the radio, good luck!
Every time we discuss external tuners on reflectors, a few people have to jump in and say that you need to have resonant antennas, so why would you ever used an external tuner, when the IC-7300 has a built-in tuner. The internal tuners in Icom radios will usually only match an SWR mismatch of 3:1. This is unfortunate, as Elecraft has had built-in tuners that handle 10:1 SWR mismatch for years. I had one in my K2. If you just need a slight tweak of your antenna to cover entire HF Bands, you may not need an external tuner at all. For the rest of us, external tuners allow us to greatly expand the Bands and Modes we can use with compromise antennas.
Elecraft KAT-500 Tuner
This is a great tuner, although not inexpensive. It is built to handle 500 watts, as a companion to the Elecraft KPA-500 500W HF Linear Amplifier. It has 3 antenna ports. It does a great job of tuning and, like most automatic antenna tuners, it is very LOUD when it has to search for a match. In fact, this is the loudest tuner I have ever seen. That is really my only complaint about it. If you go to a previously-used frequency, tuning is very quick and you barely notice the noise.
I do not use the power from my IC-7300 to power this tuner. The maximum current needed by the KAT-500 is close to the 1 Amp maximum current that the Icom rigs normally supply on the antenna tuner port. So I suggest using your separate station power supply for ht tuner. I just connect the data plug on the Antenna tuner cable to the radio, then connect the separate power connector to my main supply.
The interface is a little quirky. It seems that pressing the TUNE button on the rig can do different things under different situations. One thing I quickly discovered is that you need to TURN ON power to the Tuner before you power-u[ the Rig. Then pressing the TUNE button on the IC-7300 seems to tune the KAT-500. You can also press the TUNE button on the KAT-500 to tune the antenna matching network. If you turn on the IC-7300 before the tuner, pressing the TUNE button on the IC-7300 attempts to tune the internal tuner.
LDG Electronics IT-100 Tuner
This LDG Tuner is a perfect match for the IC-7300. If you do not need the flexibility of the KAT-500 or the increased power handling capability, this is what I would recommend. It comes with the cable you need to connect it to the Radio. So it is really just plug-and-play. Since it is powered by the IC-7300, there is no power sequencing issue. operation is simple. you just press the TUNE button on the Radio or on the Tuner and it seems to do the same thing. It can take several seconds to tune on a frequency for the first time. It is a little loud, but much quieter than the KAT-500 Tuner. I used an early version of this with my Ic-7000 in a Mobile setup for a number of years. It just worked flawlessly. I just bought the new one with hopes of installing it for Mobile use with the IC-7300.
Other External Tuners
It has been mentioned to me that there are other Tuners that can also be used with the IC-7300. MFJ makes some fine tuners. I have a remote MFJ tuner that I plan to try at some point. I have used it successfully with an IC-7600 and a Yaesu FTDX-3000. I suspect it will work fine with the 7300, but I will need to resort to the forced tone output by using RTTY or AM mode. That is a bit of a pain, but usually works with any RF-sensing tuner. If only all Tuner manufacturers would offer the Icom AH-4 tuning interface.
Both of these tuners can be used with the IC-7300. Operation of the Elecraft tuner with the IC-7300 is a little confusing, but it works fine, once you get the hang of it. Operation of the LDG IT-100 with the IC-7300 feels very natural and foolproof. It integrates as nicely as an internal tuner. If you are buying a Tuner just for the IC-7300, I would recommend the LDG IT-100. If you are using the KAT-500, you probably already have it to use with other radios.
The IT-100 integrates so nicely with the IC-7300 that it will be staying with that radio permanently. I will be keeping the Elecraft KAT-500 matched with my IC-7600.