Tuner lovers and radio experts, I need your help!

Beekyman

Hey guys, as a ham radio operator that design on PDF does indeed look like a modified cubicle quad antenna. I own the Magnum Dynalab whip antenna and much like any other antenna it benefits greatly from a good ground or "counterpoise". I have a ground line running from the mounting bracket from my Magnum Dynalab whip antenna and it is grounded to my earth ground on my satellite dish although a cold water pipe will do the job quite nicely. I also have always had very good sucess with the standard flexible ribbon dipole style antennas that sell for about 5 $ at your local RS. Rabbit ears work very well and are adjustable and tunable. If you can find one and have the space, turnstile antennas seen to be the best all around antennas that i have come across for my applications. Good luck and happy experimenting. Keep us posted and send pics if you can.

Yashu

Well, not ready to try it yet, however, I am intrigued by what you are saying about the grounding. Are you saying that I should ground the body of the antenna bottom to an earth ground? Could this be the source of all the crackling? I can take a little hiss, but the crackle makes it basically impossible to listen. It never used to do this... could it be the tuner? It only does it on the one station though... so I don't think it is the tuner, but who knows.

PeteTy

ok ill give it a shot

wave length = speed / frequency

88-92Mhz call it 90Mhz

x? = 186000miles/sec / 90e6/sec = 0.00207 miles = 10.92 feet

this is the ideal ie the speed of light in a vacuum

a centerfed / voltage feed dipole needs to be half that
5.465'

now since the wire has thickness .048" dia
the ratio of the diameter/to the wavelength 5.465/ .0048/12 =1:14000
this changes it a bit so multiply that by .98 for that big wire 5.35'
5' 4" this gives the dipole impedance just about 65 ohms
pretty close for that 72ohm coax connector

the T shaped thingy made out of 300Ohm twinlead adds a second conductor in parallel and makes that ratio about half ... 260ohms is what that antenna actually is but still close (2^2 times)

youll find the one that comes with the radio is probably about 6" shorter so you can add about 2.75" to either end. origional center about 98Mhz

if you know where the radio station is that you are interested in face this normal, right angle.
ie station north of you dipole stretched e-w.

the station is probably vertically polarized that means up and down may be better but this removes the directional idea.

if you want to make it more directional you can add more elements making a yagi. this involves another wire about 10 percent longer and parrallel about 10% less than the wavelength behind this is call a reflector
10% shorter in front is called a director. thees can be added on to make the directionallity tighter and tighter...

a single wire instead of the twin lead and the coax is for that 72ohm barrel plug

the thinner the wire on the dipole and elements the closer the tuning can come. this is a single piece of #18 wire ( the 300ohm twinlead )

the twinlead is 4x the impedance 4x the effective diameter

thicker wire is more broad band.

if you used like 22 gauge wire and coax you could snip off the ends and watch the signal strength meter to get THE station you want.

the TV antennas on the roof in vhf are about 3/8" in diameter and work well for 2 - 13 channels fm band is between 6+7 so is vhf police and fire.

the uhf channels work with 6" or so wavelength.
dipoles that diameter to wavelength gets to be more like 50 than 14,000 so the impedance is more like 50ohm length is .9 rather than .98

i made a very nice yagi for tv channel48 using phone wire scotch tape and a 3x5 card, far better than the $100 one on the roof, which isnt close to one channel antenna.

fm yagi with only 3 elements is 15' x5' maybe a bit unweildy for an apartment
and better with bamboo poles than plywood

you can make one with squares like the guy mentions in another message
these are 1/4wave on aside squares
3 element yagi 2.5' square 7.5' long gooder for apartment


metal window frames, new places have metal studs.. pipes, Aluminum siding and whatnot are all part of the picture. so a pole on the roof really helps, it gives you more control. everything around is part of that antenna you made. depending on wether you are in or out of phase and the distance from it it can add or subtract from the antenna you just thought you made correctly so experment with the placement

This is true hobby stuff so give it a try. you will get better results than almost anything you buy and save a lot of $$.

theres a lot of computers around nowdays this can be a big source of noise in that 100-600 mhz area, but can hope those are in a nice sealed closed metal box,
hope is always the last refuge.