Copyright Kent Royce 2018
All images © 2003-2018 Kent Royce.
The inverted L sets the standard for 160 metre antennas but the draw back is getting a good ground radial system. This is required to reduce your ground losses and radiate a decent signal. It’s easy to warm the ground with 95% ground losses on 160. Yes 100 watts in 5 watts out. Top band is not easy but that’s what makes it more interesting and this drives me to improve what I have.
Radiating some RF sounds easy, one of the old sayings you have no doubt heard many times is ” it loads up with my tuner” this doesn't mean you are radiating any RF. A dummy load gives you a great SWR but doesn’t radiate a signal. How many times do you hear ” my
G5RV loads up brilliant on 160” the amusing thing about this is, if you have room for a G5RV you have room to put up something that will put out a reasonable signal on 160. Yes I know what you will say… but I want to work all bands. Then read on.
Most systems only achieve about 30% efficiency and that’s very good for 160 metres A little improvement can make all the difference between a poor signal and a strong one, especially when your maximum permitted power is 32 watts, you’ll need all the help you can get.
Well things have moved on from the antenna above and I feel I have now made the best or most efficient inverted L I have used to date.
The earth system is still very important but I have found the earth stakes are a waste of time unless you require an electrical earth. Put out some radials and things will improve it’s as simple as that, but for the big jump in performance you need a transformer.
I used the FCP transformer and achieved some great results so I purchased 2 more iron cores rings and passed one on to a friend to convert him. Just make this point clear...it’s NOT a balun it’s a transformer and that is the important thing here. Check out this web site for the FCP. http://oldcyberdude.com/sample-page/antennas/160m-folded-counterpoise/
Do a search on the internet and you will find loads of information on the FCP transformer. This is the most important part about this inverted L. You will hear me on 160mtrs even during daylight when we have reasonable conditions and I do not use more than 30 watts. The thing you are trying to achieve here is better efficiency.
A simple inverted L will show a great match on your analyser and it will be almost 50 ohms, a good SWR but your precious power is keeping the worms warm and not being radiated. Please don’t make the mistake and think that a good SWR equals a good antenna, it’s the radiated RF that's the difficult bit to get right. I would suggest that anyone who wants to get on 160 metres gives this a try. You have nothing to lose and a you could be a great signal on 160 meters.
Shunt coil & FCP transformer with the shunt coils. This is my old inverted L that worked OK but not very efficient comparted to the L i am using today.
This page is about my work developing my Inverted L For 160 meters. I have tried many variations of the inverted L and these are my findings after 15 years.
Many thanks for visiting my Website I hope you find it interesting
Amateur Radio Website
Vielen Dank fur Ihren Besuch auf meiner Website. Ich hoffe Sie finden etwas interessantes
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I used an FCP inverted L for a number of years with OK results but nothing to convince me it was better than my original inverted L with just a few radials.
I removed the FCP and installed an inverted L with a shunt coil configuration.
The again was a good antenna and a real improvement over the standard inverted L. This configuration I used for a year or so until I decided to revisit the FCP transformer idea.
I installed the FCP transformer and decided to have a play with the shunt coils at the base of my inverted L to improve the match. Because i wasn't using the folded counter poise the match was not so good.
I connected the Antenna Analyser and found the usual 25 Ohms at the feed point on the FCP. I then connected my old loading coil from the FCP antenna side down to the top of my original shunt coil. To my surprise I had a match of 45 Ohms and X = 0 @ 1946khz so I was just where I wanted to operate.
I have to admit I wasn’t convinced I had improved anything regarding the performance of the inverted L but to my surprise it was much better when I checked out my signals on the usual SDR sites. I can only put this down to decreased losses. I decided to remove the shunt coils and wind the transformer to give me a better match against my earth system. This inverted L is proving to be much better than any previous inverted Ls I have built to date. Testing continues.
This is a unique 1:1 transmission line transformer intended to provide highest possible isolation between input and output. Consequently there is no direct electrical connection between the input and output with all RF energy being conducted through the specialized iron powder core. Specifications meet the K2AV FCP Isolation Transformer requirements for use with his Folded Counterpoise for 160 or 80 meters.