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Author Topic: When Is A Separate Antenna Tuner Required?  (Read 1460 times)
10CVALLEYVOL
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Posts: 43




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« on: February 24, 2006, 04:16:31 PM »

This I'm sure is an elementry question for most reading this, but I am a little confused about some recommendations made by some manufacturers of antennas. I am getting ready to install a Carolina Windom 80 Short antenna as my first antenna. I was told that an antenna tuner is required to properly match up with the transceiver. The one one I am condidering is the Kenwood TS-2000 which is equipped with a tuner. Will this be all I need, or do I need to purchase a separate antenna tuner.

Thanks in advance for any help with this question....
Ed
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K7PEH
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Posts: 1125




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« Reply #1 on: February 24, 2006, 08:16:51 PM »

In general, the built-in antenna tuners are limited in their range and ability to flatten the SWR on your transmission line.  I think they can handle something like a 3:1 SWR but not much more than that.

I don't know what kind of SWR you will be faced with but I would go with an external antenna tuner.  It certainly gives you more degrees of freedom in handling your antenna system.

Of course, there are a whole variety of tuners out there both used and new but I will leave you with a recommendation.  I submit that the Palstar AT1KM would be a good tuner to use.  I have one and I love it.  Read the reviews.  Anything Palstar makes seems to be of top quality.  You can certainly get a cheaper tuner but I doubt you can get better unless you buy one of the newer Palstar antenna tuners.
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K7PEH
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« Reply #2 on: February 24, 2006, 08:25:17 PM »

Post-script on my previous post (post post script)...

I looked up the Carolina Window Short-80 and see that it requires a span of 100 feet.  I have an alternative antenna suggestion.  This is one I used for a year or so.  Run a center fed dipole in that 100 feet.  And, like the short-80 antenna let the ends drop down, about 12 to 15 feet on each side.  Thus, your antenna is then 124 to 130 feet of wire in the 100 foot span.

Now, feed that at the center with balanced 450-ohm ladder line.  This ladder line then runs all the way back to the shack at the tuner.  With the tuner I suggested previously, or one similar, you will have an all band antenna.  Actually, you can do this with just the 100 feet of wire but I found that the ends dropping down giving me more wire length made it very easy to tune on the 75 and 80 meter bands.

In this configuration, do not use coax at all.  Use the 450 ohm ladder (aka window) line which is very low loss compared to the coax.  You will have high SWR on any other band except for around 75 m and even on 75 you will have an SWR around 6 or more because of the 450-ohm ladder line.  But, if you are using ladder line this mismatch will not matter that much.
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KC9HVN
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Posts: 23




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« Reply #3 on: March 07, 2006, 12:19:52 PM »

No, you won't need an additional tuner. The Windom will give you a pretty decent SWR on most all bands, the internal tuner in the TS 2000 is sufficient to bring what mismatch exists (usually 2:1 or so) down to what the transitorized finals in the Kenwood would like to see, something like 1:1.3 or better.

I use a Windom and an old TS 830 with no tuner at all, that rig has tube finals and can handle up to a 1:3 swr with no prob. My TS 130 (a transistor rig) rquires a tiny bit of matching to work correctly, so I use an LDG Z100 to take care of the slight mismatch.

Have fun

73's
Mark
AB9LZ
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N5XM
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Posts: 242




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« Reply #4 on: March 18, 2006, 06:02:15 AM »

I've never been too fond of internal tuners. Sure, they get the SWR down reasonably, and you can spend the entirety of your Ham life chasing 1.0 to 1, but all it takes is a tiny bit of tweaking and that's exactly what you have,  1.0 to 1.  I understand it's only a flat SWR at the tuner, but I prefer the tuner take that small amount of heat instead of the rig.  

I know, I know, the tuner doesn't change a thing at the feedpoint unless you use half-wavelength multiples, and if you operate on more than one band with one antenna, this is very hard.  I understand an external tuner doesn't change radiation resistance or antenna efficiency, but hey, unless you live out in the country where  you can put up a big tower out in the middle of a field, aren't all antennas compromise antennas?

I guess I just like having two or three extra knobs to twiddle, hi.  See you on the air!  73, Richard, n5xm
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K8AG
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Posts: 351




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« Reply #5 on: April 13, 2006, 10:25:25 AM »

Like has been said, internal tuners give you a small amount of flexability (for substantial complexity in my opinion).  They are NOT meant to replace real external tuners.

Also be aware that a tuner really tunes the line, not the antenna.  High SWR on a significant run of coax can attenuate a signal drastically.  Best to tune at the antenna so the signals through any connecting coax have a low SWR.

My 2 cents.

73, JP, K8AG
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