Antenna Tuner

[dnlbrrg]

I've been researching plans for a home made SW antenna and came across a design that seems easy enough to build, the broomstick special.

All seems fine and dandy but... where do I find an antenna tunner?

The design calls for an antenna tuner, I checked radioshack.com and they didn't seem to have them.

 

[jackj]

Try doing an Internet search for "Antenna tuner". You'll find bunches of places that sell them.

 

[majoco]

Before you jump in at the deep end and spend money on a tuner, what sort of radio are you going to connect to it?

How well a tuner works is very dependant on the antenna socket impedance on the radio - high impedance unbalanced may work well, coaxial low impedance not so well, the tuner tends to revert to a bandpass or high pass filter. A radio where you intend to connect to a whip (Kaito 1103, Grundig/Eton G5 series etc) usually have a high impedance FET amplifer which may well overload or go pop with static discharge.

 

[k9rzz]

Can you share the plans? Not sure why you would need a tuner for listening unless you're going real low in frequency.

 

[dnlbrrg]

Yes, I can share the plans and I can tell you the type of radio I'm connecting this to.

Well, as far as the radio, is the Grundig Field Radio Deluxe. I also have the Grundig G3 but I don't want to start with an antenna for that one because the antenna socket is a mini plug.

As far as the plans go, click on this link:
Broomstick Special, easy-to-build shortwave antenna -- on hard-core-dx.com

I could describe them to you but the link makes it a little clearer.

Basically, according to the recipe, I can make do without the antenna tuner but it will be better is I have one. This guy uses a capacitor from an old radio, but I have no clue how to do that or even how to wire it to the antenna.

I think I'm gonna build one tonight, without the tuner, and see how it compares to the internal antenna.

Down the road I might clip it to the telescope antenna and see how that works too. Eventually though, I want to get the tuner thing figured out.

 

[jackj]

A tuner will help...some. This is a short antenna so don't expect it to work much better than the telescoping antenna on your radio, even with a tuner. An antenna tuner is used to match the output impedance of the antenna to the input impedance of the radio and that will improve the transfer of power to the radio. Once the impedance is matched, the next important antenna characteristic is it's capture area and a short antenna just won't capture as much power as one that approaches 1/4 wave length. Try it without the tuner first and if you see some improvement, if you do then build the tuner. You might have a better performance improvement by just wrapping the bare end of a 20' long wire around the telescoping antenna and throwing it out on the floor.

 

[k9rzz]

Well, it will be a fun project and you'll learn from it I'm sure.

 

[Pigmeat]

I've actually used a random wire antenna tuner (MFJ hamfest special) with various Broomsticks I've built. It works well above 5000 khz,but below that,not much better than 20 feet of wire feeding the antenna tuner They're very low noise,though,and perform well if you don't have the room for larger antennas.

Back when I was an active pirate,I experimented with a Broomstick w/ a capacitance hat,ie; pie pan. Running a mighty 14 watts of carrier through it,I was heard 400 miles away,until the thing started behaving like a Tesla coil, kicking out sparks,smoke and melting the 2 inch i.d. PVC pipe I used to build it. Apparently the things build up quite a bit of voltage when hooked to a transmitter running any sort of power?

 

[jackj]

You did all THAT with 14 watts, Pigmeat. WOW!

 

[LtDoc]

I looked at the site but couldn't get any further than the first 'page' of it, the 'resonance' and other sections were inaccessible. So, going only by the first page description you have a random length, shortened antenna that's helically wound. While it certainly may be better than the supplied antenna with most radios, it is also certainly not going to be very good. If you are limited to this sort of contrivance by where you live, then give it a shot. I think I'd hold off on buying a tuner though, if you are only going to be listening. Transmitting is a different story all together, and you'd be better off throwing a random length wire, related to the wave length of the frequency, out a window! Tie a helium balloon on the end of that wire and it'd be even better. Would it really? No, but that 'broomstick' antenna would be worse.
- 'Doc

 

[Pigmeat]

You did all THAT with 14 watts, Pigmeat. WOW!

Surprised the Hell out of me,lol. Now if I could find that old CB linear,I could build a homemade death-ray and long distance turkey fryer by combining the two.

Arnie Coro is a big proponent of the Broomstick. They do tend to pick up semi-dx an hour or so earlier before my regular antenna's do. They were always very good for logging the stronger African domestic stations in the late afternoon. I wouldn't be able to hear a hetrodyne on the 80 meter dipole,then switch to the 5 foot broomstick and have them popping up weak but steady across the band.

Wiring it to a junked tuning capacitor is a cinch and works well. When I get home I'll explore my junk pile and give you the wiring info. You really don't have to solder the contacts. Small alligator clips attached to the capacitor leads will do just fine