Welcome to project #37859 – the never ending saga of improving my signal!
I’ve tried all sorts of different wire antennas here at the house in suburbia, and all have performed about as well as I’d expect them to given their compromised position & setup. However, I took a step back after I started realizing that I was consistently pressing the tune button [AT] on my Kenwood TS-590SG to tune the antenna. Problem is I was using multiband antennas that had a really narrow bandwidth in any given band, especially 30 meters & down. It’s kind of what I had to deal with, I wanted the ability to hop on as many bands as possible using the smallest amount of space possible. Kind of hard to do that with ham radio efficiently when you think about it. Not to mention that the SWR feedline loss was probably killing me on certain bands. I was probably transmitting at QRP levels in certain areas of the spectrum which will definitely work when the conditions are right, but be tough otherwise. While I’m tickled at everything I have accomplished on HF thus far, I know I can do better – and I know I can make my setup more efficient.
Antenna ‘systems’ can be complex things – some of which I still don’t understand – but I’m getting there. After a long read of “Another look at reflections” by W8KHK (M. Walter Maxwell), (a long read BTW – but probably the most informative document I’ve read on transmission line theory). One statement Maxwell wrote really stood out to me & helped explain a lot:
“The transmitter doesn’t “see” an SWR at all — only an impedance resulting from the SWR. And the impedances are matchable without concern for the SWR. This is one of the most important points of confusion at issue.”
This was definitely a point I was confused on, but it’s all that much clearer now. In a perfect world, we’d all have perfectly matched systems, but I’ve realized that things don’t have to be ‘perfect’ in order for them to work, or even work good! There are compromises in every signal chain, and that’s OK!
My viewpoints on tuners in the shack have started shifting a bit though – while I understand the appeal/convenience/simplicity, practically speaking a remote tuner is really the way to go after further consideration. The cost of remote tuners seem to be coming down as of late, and more and more I’m seeing antenna wizards even crafting their own or even modifying existing in the shack tuners to perform as remote! Some ingenious stuff!
I discovered a product made by LDG called the RT-100. It’s a 125 watt (peak) coax in & out remote tuner for $229. Say what? Wait… I paid $199 for the KT-100 auto-tuner which just sits inside my shack, and presents an impedance that’s more acceptable to my transceivers (works with both my 590SG & 480SAT to give them a bit wider range than the internal tuner). I’m not sure how ‘new’ the RT-100 is, though the earliest review I can find on eHam is November 2013. So this product has been around for a few years, & there’s some reviews online but not like the reviews for the tuners inside the shack, which leads me to believe that remote tuners are not as common of a product with hams. Initially LDG sold the RC-100 controller separately, but it’s now sold as a combo (it can also be used with other Bias-T boxes).
I’d heard of remote tuners from other hams, and that if tuners were used at all, then remote is definitely the way to go. I didn’t understand this initially as a new ham & the importance of matching the antenna as close to the feedpoint as possible. Now keep in mind, it usually takes a pretty high SWR & high attenuation in order for any significant loss to occur on the feedline. A 6:1 mismatch will double your feedline loss, but unless your run is long (over 100′ I’d say?) and you are using low quality coax, you might not see much of an improvement. But in my situation, where I like to take my antennas vertical, the remote tuner will allow me to match the antenna perfectly at the feed point, so I’d be able to deploy a flagpole type vertical of a very short height, and be able to work multiple bands somewhat efficiently. (Actually this tuner will work on ANY coax fed antenna so the options are pretty wide!) Matter of fact, I plan on using it with the 9:1 unun I just built a few weeks ago coupled to a fiberglass pole to test out capability for portable use!
What really interested me in this product was the flexibility with the coax in & out ports. You can essentially hook this thing up to a number of different baluns and experiment, or if you prefer you can immediately split the coax out port with one of these guys:
Don’t get me wrong, I’d love to have a resonant monoband antenna perfectly matched for every band available, but being realistic – that would take up a huge amount of space! Not to mention a lot of feedline to get them all spaced out properly! Even the remote tuner is sort of a Band-Aid in the whole process, but I consider it to be a ‘more-efficient’ Band-Aid!
The build quality is typical LDG stuff – seems like it’ll hold up well to the elements, I may house the external unit in another box just to keep it even further weather protected. The sun can be absolutely brutal in Texas! This was the only barefoot power remote tuner that I could find on the market today, surprised there isn’t more since I’m sure the majority of hams operate at barefoot power.
More to come on the LDG RT-100. Lets make some contacts!