HF radio antenna - DIY

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I have one sitting in the back of the Pathy still waiting to be used. I have one in the backyard and regularly work Cape York to Tassy if only the birds stop picking the insulation off.
 
Thank god for that. I thought for a minute there it was one more "must have" piece of equipment that I needed to get a clear signal from my detector :lol:
 
Are the bands still quiet Jaros??
I haven't fired up HF for years?

Not even sure about 2 mtr or 70cm activity around here any more?

Is there still that online ham thing going on?
 
Most 2mtr conversations are done via repeaters placed strategically all over the place. I spoke on 2M a while ago to 2 fellas whoe were about 50Klms away not using a repeater and they were surprised how clear it was. My 2 mtr aerial is above the rooftops around us because of all the tin roofs around the house-including mine.
I haven't tried the online gear.I dunno it's not as tech as doing it yourself.
Cheers.
Jaros. VK4NLS.
 
Yep. :)
Co-Linear has the coax cut and alternating between the braid and center conductor.
Plus cut to a certain length.

A thick white glass pole is a give away.
I have one here for Mid Band.

BigL said:
Tathradj said:
From the pl259 connector to the end of the braid acts as
a ground plane for the inner that is exposed which is the radiator
element.
Buffs can correct me at the moment as I am mentally flat,
I think it is called a co-linear ground plane.
Click to expand...
coaxial ground plane its called. A colinear is a type of phased array, they have what looks like coils in the middle, these coils change the phase and in doing so results in gain.... +dB
Click to expand...
 
well there ya go... looks like a few calls frequent this website. I let my VK3 call lapse a few years ago, use to work 40 & 15m quite a lot mainly mobile. Occasionally joined the 40m 7:30 net for some regular DX on a delta up about 90 ft. Ran a home-brew 2 ele phased array on 15. Got rid of a K3 & Icom 7000, though still got a 520S tucked away. HF was my thing.

Actually still enjoy knocking up the occasional electronic device, latest project is a Pass Labs Class A amp, 100W push pull fully balanced - a Nelson Pass design. Got a noice PI coil in the works too ;)
 
BigL said:
468 / MHz = 1/2 wave length (ft)
Measure and cut a length of wire to your half wave length answer
Cut the wire in half and then feed each piece of wire with your coax, + one side, - the other
you now have a half wave dipole which can be run vertical, horizontal or even at 45deg... whatever you like
the higher you can get it the better
Click to expand...

Hi BigL,

I am not that bright with many things so I ask questions to confirm what I don't know. :)

As I understand it...

468 divided by the frequency = a half wave length in Feet ? (why 468 ? please)

Convert that to Centimeters to measure 1/2 wave length of wire. (is that acceptable)

Fold in half and cut it, to get a 1/4 wave length x2,... feed one 1/4 side from the shield, and the other 1/4 side from the core.

Preferably check the SWR.... how do I tune the antenna ? If I want to or need to.

Is there a preferred spacing between the two 1/4 wave elements at the feed point ?

Would it be worth going up to 1/2 wave elements ?

If hanging it vertically in a tree, which end up is best ?

Is this a suitable antenna for uhf CB and vhf Marine, for a temporary base camp, I hand the girls uhf walkies and everyone goes for a wander,
so a base set would be a bit different for the kids to use. Generally I give everyone a cheap Baofeng 3.7Vdc GT-1's programmed to uhf CB,
at $20ea I am not worried if they are drowned or dropped.
If it would work, I could get the girls to make an antenna each, set up and test their work :lol: :lol: :lol: (camping STEMM classes)

A 27mhz setup to follow a bit of skip would astonish them, a must do. ;)

See how uneducated I am? ;)

Cheers.
 
Loved my Kenwood 520s, seems like i haven't been on the waves for 40 years,still pay my dues each year as, one day :lol: :lol: :lol:
Mackka VK1KJM portable VK4
 
Greenhornet_au said:
BigL said:
468 / MHz = 1/2 wave length (ft)
Measure and cut a length of wire to your half wave length answer
Cut the wire in half and then feed each piece of wire with your coax, + one side, - the other
you now have a half wave dipole which can be run vertical, horizontal or even at 45deg... whatever you like
the higher you can get it the better
Click to expand...

Hi BigL,

I am not that bright with many things so I ask questions to confirm what I don't know. :)

As I understand it...

468 divided by the frequency = a half wave length in Feet ? (why 468 ? please)
468 is a constant derived from a RF wavelength or 0.5 lambda

Convert that to Centimeters to measure 1/2 wave length of wire. (is that acceptable)
yes 468/Mhz/3.2808x100 = cm

Fold in half and cut it, to get a 1/4 wave length x2,... feed one 1/4 side from the shield, and the other 1/4 side from the core.
correct

Preferably check the SWR.... how do I tune the antenna ? If I want to or need to.
what ever your calculations work out, add a couple of inches to each 1/4 wave side, that way your antenna should be resonant below your desired frequency, then you just trim maybe 5mm from each element side until the SWR is acceptable, anything <=1.5 SWR is fine. Best to start with wire to long than too short for obvious reasons

Is there a preferred spacing between the two 1/4 wave elements at the feed point ?
1/2 inch is fine

Would it be worth going up to 1/2 wave elements ?
no, because your feedpoint wont be around 72 ohm which is what your aiming for

If hanging it vertically in a tree, which end up is best ?
either end if you get it high enough, like greater that 1/2 a wavelength high, otherwise id have the positive side up

Is this a suitable antenna for uhf CB and vhf Marine, for a temporary base camp, I hand the girls uhf walkies and everyone goes for a wander,
so a base set would be a bit different for the kids to use. Generally I give everyone a cheap Baofeng 3.7Vdc GT-1's programmed to uhf CB,
at $20ea I am not worried if they are drowned or dropped.
If it would work, I could get the girls to make an antenna each, set up and test their work :lol: :lol: :lol: (camping STEMM classes)
i dont see why not... wire antenna is a lot easier to get high up a tree than whips ect

A 27mhz setup to follow a bit of skip would astonish them, a must do. ;)

See how uneducated I am? ;)

Cheers.
Click to expand...
all answered for you in the above
 
BigL said:
all answered for you in the above
Click to expand...

Err...ok..

I'm a bit confused by that, but whatever.

Edit - OHhh, looked closer at my quoted text, thank you.

Told you I am simple :awful:

Edit - Edit - Big thank you BigL,

I have learned something new from you, now I can pass it on. My kids are fond of my antics, love using the uhf handhelds we have some general discussions
about wavelengths and frequencies, radio propagation and some history of communications before their and my time.

I need to find a sideband 27mhz set now.

They will spaz out at actually building a functional antenna, even the 5 yr old.

Thank you.

I fancied tying some cord to the tip of a whip antenna, and using a slingshot so I could pull the whip up into into a tree with the cord, and back down with the coax.
Camping can be good fun.

Taking a 44 drum, to do a drum air pressure crush experiment next camp too. Heat the water over the camp fire, seal it and roll it into the river edge. POP !! :clap:
Throw it back into the trailer to get recycled. ;)
 
That's where "some" tech training comes into it--In Vic the SEC and Railways guys came in to the tech course at PMG to learn how and why "it" works.
No offense.
 
I'd suggest a half wave dipole made of wire for 27mHz and as Jaros highlighted a 1/4 wave ground plane for UHF.

Why.. because the radiation patterns will better suit each band.

Get a SO239 and make a 1/4 wave with it like the below pic... bend the radials down slightly same as in the pic, this will drop the feed point impedance down to around 50 ohm and make it a perfect match for the transceiver.. You'll still have to tune it with a SWR meter, but you only trim the (+) vertical element

1628513825_25_wave.jpg


and remember, height is might... get them up as high as you can!
 
Okay.. Mr. BigL

So a full wave at 27mhz is @11m, half wave is 5.5m, therefore a half wave Dipole 27mhz is 5.5m per side of the feed in point (center). Total of 11m ?

Clearly this is a 'wide antenna' and would need to hang horizontally, if there were no very tall trees around to hang it vertically at least "a half wave length" off of the ground, or would that be a full wave length in this case ?

If horizontal I assume it best be as high as possible?
.
.
LOL, I can see my girls having fun with their slingshot...err, BAIT throwers (fishing rods at hand) ;)
Lobbing sinkers with cord attached.
.
.
The UHF, 1/4 wave, I'm all good with that.
I assume that the 'driven' element is best to have something with a low resistance, like copper or brass.

That is a nice page.
https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/

:)
 
Jaros said:
Most 2mtr conversations are done via repeaters placed strategically all over the place. I spoke on 2M a while ago to 2 fellas whoe were about 50Klms away not using a repeater and they were surprised how clear it was. My 2 mtr aerial is above the rooftops around us because of all the tin roofs around the house-including mine.
I haven't tried the online gear.I dunno it's not as tech as doing it yourself.
Cheers.
Jaros. VK4NLS.
Click to expand...

Repeaters?? What the hell are they?

Old mate of mine (RIP) from Albury, and myself in Wodonga, used to regularly have scheds with a couple of stations in Melbourne on 2m.....admittedly sometimes had to revert to CW when the going got rough on AM.

Here's my gear, and the array........those were the days :)

1628655863_imga993.jpg


1628655907_img463.jpg
 
Beautiful array you have there. I have to replace my G5RV out the back when my back feels better. Going in to hospital to have the implant and battery removed, This necessary because I can't have a MRI brain scan to sort out my vision problem in my left eye.
 

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