Antenna Tuner Question

[Jimepage]

Does anyone have any good recommendations on a good tuner for random wire antennas on HF band? I am receiving only shortwave broadcasts and wondering if a tuner would give me a decent signal over what I have now. Any suggestions or info would be great. Thanks

 

[ka3jjz]

Unless you're using a very short random wire, you likely won't need a tuner. You didn't say how long it is.

A couple of things come to mind. You are entering a world where understanding how the sun interacts with our ionosphere and influences propagation conditions. You don't need a PhD in geophysics - just understanding the basics will be enough.

HF Propagation - The RadioReference Wiki

The AE4RV propagation primer is a very good place to start. Note that you will need the Flash player to see it - be sure to allow it to run if you have one of the utilities that restrict its use. Spaceweather is also a good place to see if the sun is beginning to act up.

The other thing to try is a better antenna. The random wire is but one of a great many types - what is it you are trying to hear? How much space do you have to work with? This is one side of the hobby where it's not necessarily expensive if you know how to solder and use some simple tools - and you learn a lot by experimenting. Again, our wiki has several links with more information...

HF Antennas - The RadioReference Wiki

best regards..Mike

 

[K9WG]

Don't have any firsthand experience but here is one for SWL

MFJ Enterprises Inc.

 

[majoco]

IMHO a tuner is not a substitute for a good longwire with a matching transformer (a un-un) up at the end with coax down to your radio. See a PAR End Fed SWL antenna and then make your own.

To get the best out of a 'tuner' you need to bring the long wire down to the tuner without any coax. This leaves you wide open to any noise from within your house, but you will be able to peak the signal.

By connecting the coax up at the end of the longwire and then bringing that to your receiver, you will get the best reception on those frequencies where the longwire is a low impedance - multiples of a quarter wavelength. At other frequencies the capacitance of the coax just bypasses the signal to ground. Your tuner in this setup just acts like a bandpass filter.

 

[LtDoc]

'Tuners' are not the 'cure all' that some people think they are. They only transform one impedance to another one closer to what your radio want's to 'see'. They don't change, or make an antenna 'better'/resonant, they only allow for more energy to be transferred to/from that antenna to your radio because of incorrect impedance matching.
Having said that...
If you only have one antenna for whatever reason, a tuner can make that antenna more 'usable' on a wider range of frequencies than not having a tuner. The key word in all that is "usable", which certainly doesn't mean it will work -well-, it just 'works'.
- 'Doc

(I've used tuners for a lot of years, they have made some antennas I've used end up working better. But they don't do 'miracles'!)

 

[W2NJS]

If all you're doing is receiving then don't waste your money on a tuner. Just get the antenna wire itself as long as possible. The primary and usual function of an antenna tuner is to match the output impedance of a transmitter to the impedance of the antenna, and when used in conjunction with a receiver this may increase the performance of the system on receive by a small amount, but if you're not involved with a transmitter then don't bother with a tuner unless the antenna is very, very short, like five or ten feet.

 

[prcguy]

You will probably see more improvement by going to a different type of antenna over using a tuner. I abandoned end fed wires in favor of dipoles fed with balanced line years ago and have never looked back.

If you make a dipole as long as you have room for, maybe 50 to 100ft is good, then feed it with simple 300ohm TV twinlead to the radio you might be surprised. You can solder a PL-259 right to the twin lead for the radio connection and getting the antenna away from the house can benefit from less noise pickup.

You can take this up another notch by placing a 1:1 choke balun at the radio end and use a very short piece of coax between the balun and radio.

If you have room for at least 75ft of antenna it can also be used for transmitting on all HF bands from 80m on up with a tuner.
prcguy

 

[Jimepage]

Wow Great information guys very much appreciated. I am stuck in an apartment the wall I run my wire gives me only approx 20ft. I have tried to go around the whole edge of the carpet making a big square but made little or no difference. I have very few options being that I am in an apartment and my neighbors are the type to sit at home collect foodstamps and sit on their porch and tell the management if I even think about putting anything outside. I do appreciate all the infomation. I will certainly be reading the links you have given and learning also about j poles. I just wanted to exhaust my options before taking the plunge and buying a welbrook loop to use indoors. Atleast with one of those I can null out some of the noise. I can dream of having a big yard to use for now. Thanks guys.!

 

[ka3jjz]

At 20 foot that antenna isn't going to be very efficient below about 12 mhz or so. With the flux levels still below 100, that isn't going to help matters any.

You might consider turning that 'square' into a loop fed by a 9:1 transformer. Several turns to make it 80 or 100 foot would make it much more resonant across more of the spectrum, and the transformer will help with isolation. Our wiki has a few links on 9:1 transformers, and there are a few folks - WinRadio and Palomar come to mind- that make their own very inexpensively. That's not to say the Wellbrooks don't work well - they do - but you should try something less expensive first. You might find it works better for your applications for a whole lot less money

best regards..Mike

 

[robschonk]

Do some googling on "apartment dwellers antenna" or similar.

There are all sorts of things you can do. One is to tap into the seamless aluminum gutter. Another would be to just string up some #24 magnet wire over to a tree, or something. Almost invisible, but the birds will fly into it and break it. Use #6 fishing line and a sling shot to get it up. Also try stringing it under the eaves where no one will notice it. Where theres a will, theres a way.....

Heck, in my college days, we used to load up the mattress springs, and work DX on 20.

Rob N4JKL

 

[nanZor]

I've used this type of loop vertically in a restricted indoor environment and it worked well enough:

Here's a real cheap antenna to make from 160m - 6m... and it WORKS!

I didn't care about 160m, so I didn't even need the inductor. It was fun tuning it with the coax stubs.

I *used* to use that, however my neighbors decided to go BPL on me, and even a small loop could no longer null the noise since it was coming from all directions. I even rotated it, but alas, no go.

Call me the odd-duck in the group, but I now run a vertical indoors, since it was easy to find a noise-free slice of real-estate on the far side of the house near the bay windows. Move it a few feet sideways, and all is lost to local noise. And I run only one radial believe it or not, which gives me directionality away from the house. I don't recommend a vertical indoors to anyone unless you have the patience to find the sweet spot. I did!

 

[Jimepage]

Thanks guys for the info lots of info I didnt know before.

 

[prcguy]

If your confined to an apartment I would try for a small active whip antenna that you could stick out the window. Some of these are very small, about 3ft long and can work very well.

You really need to get these outside for maximum benefit. They are not really a preamplifier but an electronic impedance matching circuit to turn the multi thousand ohm impedance of a 3ft HF whip to 50ohms and anything around the whip can degrade the performance.
prcguy

 

[nanZor]

Here's what I'm running now - an "L" fed with twinlead to an old Swan manual t-type transmatch:

The "Up and Outer" Antenna

My elements are only about 8 feet on each leg - it was the only antenna that I could "hide" not from my neighbors, but from their own QRM. Placement was tricky, but found the spot. It's not the greatest antenna to be sure, but a small antenna in a noise-free area, beat the full-size antennas I had overlapping my neighbor's noise fields.

 

[ridgescan]

What a great thread! All the best in here. RR at its finest. That is all