Ant. Tuner Question ?

[BOBRR]

Hello,

Do receiving only.
Pretty much below 30 MHz.

Have an outdoor long wire ant. about 75 ft. long.
One end goes to a Balun, then a coax run up to house.
Pretty much a typical setup.

I have read about antenna tuners. Truly know nothing about them.

With the simple long wire I use, is it worth considering an
"antenna tuner". Why ? Again, receiving only.

If so, might you suggest an inexpensive one, perhaps below $100 or so ?

In this price range, are they self, auto., tuning, or does one have to
continually adjust them ?

Not familiar with these gadgets, so any advice, caveats, etc. would be most appreciated.

Thanks,
Bob

 

[ko6jw_2]

First let's state that 75 feet is not a "long" wire. A long wire is one that is several wavelengths long. You can ignore that because everyone else does. Second, antenna tuners do not tune antennas. They provide a match between the high impedance of an end fed antenna and the low impedance of the receiver. Your price point pretty much eliminates any decent tuners. MFJ used to sell inexpensive tuners for end fed antennas. Check out their offerings. You will need a manual tuner because an automatic tuner needs to transmit a low power signal to tune up.

Depending on the type of balun you are using it may (should) lower the impedance down to something reasonable. Since you are not transmitting that may be good enough.

A tuner would need to be adjusted as you chance bands. You can adjust for maximum noise on receive and that should be close enough.

 

[majoco]

You have already changed the impedance of the antenna with the balun and the coax cable down to the receiver which we hope has a 50 or 75 ohm antenna input - you cannot now change the impedance with a tuner at the receiver - all you end up with is a preselector. If you really want a 'tuneable' antenna you should bring the 'long' wire down to the tuner and then the coax from the tuner to the radio - this of course means the drop from the end of the antenna to the tuner will pick up all your house noises.

 

[ka3jjz]

Really the term 'antenna tuner' has been misused for years. A true antenna tuner goes at the feedpoint of the antenna, and you need to send it a bit of RF to make it tune. That's fine for hams but not for listeners. A transmatch is a somewhat more accurate term, and in this case, it wouldn't buy you anything as Martin has suggested....Mike

 

[BOBRR]

Hi all,

Much thanks for the info.
Appreciate it very much. Good info. for me.

Regards,
Bob

 

[cmdrwill]

There are "tuners" which are really antenna matching boxes for receiving antennas.
MFJ does make a manual antenna "tuner" for receiving antennas,. MFJ 16010 and 9301.

 

[ka3jjz]

I didn't come up with the 9301, but I did for the 16010. I suppose you could call it a tuner, since it's used to 'tune' a random wire antenna.

It's OK to be confused. The term has been misused so often that an old saying comes to mind - repeat something false enough times, it sounds like the truth.

Mike

 

[BOBRR]

Hi,

Will look at.

Question, please, as ant theory is one of my (many) very
weak points:

When i installed the ant many years ago, I apparently put a Balun at one end to attempt
to match the the impedance of the wire ant. to the coax connected there for the run up to the house (with the coax).

Think one of these ant tuners would still be "useful," assuming the Balun is still functional after
all these years ?

Regards, stay well all,
Bob

 

[JerryX]

Just to be even more pedantic, the "balun" you're using is probably an unun. A balun is a "balanced-to-unbalanced" transformer, while an unun is an "unbalanced-to-unbalanced" transformer.

 

[ka3jjz]

Unless something has happened to the balun, Bob, I'd say no...Mike

 

[ka3jjz]

Bob if you want to improve your setup, consider adding another antenna, perhaps pointing in a different direction. This way if one antenna isn't hearing the desired station well, the other might. Propagation can be flaky like this...Mike

 

[JerryX]

Think one of these ant tuners would still be "useful," assuming the Balun is still functional after
all these years ?

What one of these boxes will do is to help transform the impedance of your random wire antenna to the 50 ohm impedance of your receiver. This will maximize energy transfer to your RX. It's easy to tune these--just turn the knobs to maximize band noise on that particular frequency. Whether or not that helps to hear stations better really depends on a lot of things, but keep in mind that signal-to-noise ratio is more important than absolute signal strength.

If your UnUn is no longer functional, you can just run the end of the wire antenna to the vicinity of your receiver and plug it directly into the antenna connector of the "tuner". To do this, just solder a banana plug on the end of the antenna wire--this will plug into the center connector of the SO239 on the tuner. Just make sure the antenna wire is either insulated or that it doesn't touch any metal objects.

 

[ka3jjz]

Tuners/transmatches are best used when the antenna isn't performing well on band(s) they don't seem to be hearing (for receiving purposes, of course). There is no broadbanded antenna that will perform the same way on all bands - physically that's not possible - but at 75 foot, you should be reasonably good to just shy of 3 Mhz (the 90 meter tropical band).

In some cases you might not notice any difference at all. It greatly depends on your antenna setup and the conditions while you are listening.

Mike

 

[ArloG]

Firstly what kind of radio are you using Bob?
I still enjoy firing up the Collins and Hammarlund shack warmers once in awhile.
I wouldn't be one but afraid of hooking up a longwire antenna directly to the terminals.
It would take quite a zap of static to span the tube plates and do much harm. But.
If you value your radio a very good idea is to use a balun that is properly grounded.
Many radios, alot of Icom's from speaking with their service center, are getting board traces and front end components blasted.
From what I get from the owners they get started and hang a wire antenna and hook them directly to the antenna terminals.
Not saying it will happen today, tomorrow, or 5 years from now. It sucks when the warranty runs out. And when you know the repair had to be done with a piece of wire to bridge the board traces.
Look at my attachment. You will see that a properly installed balun provides a good ground and does a good job of matching your radio to antenna. Plus will provide a good static drain.

That said, I use an ancient kit preselector quite a lot. Cheaper SDR radios have little if any front end filtering. Imaging from strong frequencies shows up here and there. It's said that an antenna tuner on rx wont do any good. I think they do to an extent. But your best spent money would be for a preselector, perhaps one with a switchable preamp.

Now everyone can start yelling at me. But if you get one you can try it and return it if you don't like it.

 

[JerryX]

Now everyone can start yelling at me.

Psssst, I won't start yelling at you, but will just point out that what you describe as a balun is actually an unun -- it even says so at the bottom of the second diagram you posted. I know old habits die hard, but some of us are sticklers for proper terminology.

 

[ArloG]

Psssst, I won't start yelling at you, but will just point out that what you describe as a balun is actually an unun -- it even says so at the bottom of the second diagram you posted. I know old habits die hard, but some of us are sticklers for proper terminology.

You're absolutely correct. I'm of the belief that whether balanced to balanced or unbalanced to unbalanced as long as there is provision to attach the driven elements to a good earth ground and using a good spark arrestor. Your rigs will be much better off. My terminology is a bit laxed but the intention is good.