Home made antenna question.

Homebase antenna advice and troubleshooting

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lorry
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Sun Jan 26, 2014 6:43 pm

Hi guys new here and straight in with a question as Im old school but forgotten more than I know (memory not what it was) I've been hearing in July there's going to be some changes which has sparked my interest and after a quick rummage around the loft I came out clutching a Amstrad 901 and a small mag mount, I threw it in and on the car and went off to the local hill and was amazed at the skip coming in but came home and plugged the cb into a power pack and threw the antenna out the window like a game of magnetic darts onto a wheel rim and zilch nothing but noise.

Well moneys tight until I know if I can get back into this, I have already got my eye on a bigger rig but that's another story and she hasn't surprised me yet and come up with the brilliant idea of buying it that will take time but in between I've thought about a home base antenna and I like to fiddle around and get the satisfaction of standing back and saying "I did that" even with the help of others.

So thinking back the best antenna I had was a Thunderpole/silver rod type antenna and gazing out the window I just spotted something very similar as a start base and wondered could it be done, I have a flag pole about 20 ft plus in two sections one fits inside the other about half way, I can make an insulated bracket to fit on the bottom like the previous named antennas and wondered if an ugly balun could be fitted at the base then fit the insulated bracket to lets say a piece of scaffy tube say a couple of foot welded to a plate and raw bolt to a concrete base.

I have the flagpole its painted white if its doable would all paint need to be removed or just contact points? the concrete base is in place (Old greenhouse base) Im guessing SWR adjustment through length as on piece fits inside the other, at the bottom homemade ugly balun from coax around waste pipe but what length would that be and would it depend on just about exact length of pole.

Forget it what a stupid idea you relay have forgotten more than you know Lorry just make a bracket to hold a whip antenna and stick it on top.

Cheers for reading Lorry.

Oh I have about a 16 to 18 ft fiberglass windsurfing mast for plan B I just haven't come up with how yet (inverted V dipole?)

What do you think

Dragonfly
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Sun Jan 26, 2014 10:14 pm

You might just squeeze a wire Dipole onto that fiberglass pole . 8ft 3in of wire upovers and 8ft 3in of wire downovers taped to the pole and connected in the middle by a chockblock to your coax cable .
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lorry
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Mon Jan 27, 2014 12:20 am

Hi Dragonfly I like the simplicity of this and will give it a go thanks.

Side note if my fiberglass pole is a tad short could I just twist the wire round it to take up the slack to get the same result?

Dragonfly
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Mon Jan 27, 2014 8:55 am

A winding would create a choke and shorten the wavelength , a insulated standoff from the mounting pole might work ok though .

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porky.69
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Wed Jan 29, 2014 7:49 pm

by the time you have bought all the bits you might be better of buying a silver rod antenna

lorry
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Thu Jan 30, 2014 9:31 am

I have everything from salvage but coax cable and gutted this may cost me about £10 but needs must, call me tight but I shall cry from one eye only to save water whilst handing the money over.

Thanks to dragonfly for food for thought I've decided to go with a dipole set up fixed to but easily removed from the windsurfing mast which will be fixed to a stand that I can drive over to facilitate taking it out and about transported on the roof rack but also so I can experiment using the mast to fix one side of the dipole to and the other to an tree/ Structure for horizontal use,sloping and the inverted V option that's the idea anyway.

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porky.69
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Sat Feb 01, 2014 7:56 pm

good luck with it all :D

lorry
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Sun Feb 02, 2014 9:40 am

Well I knocked the dipole on Friday and Im pleased to say after the first attempt it worked, but I put the SWR meter on and it was at just over 2 and just listening in it was bringing in a good few signals from quite respectable distances on a local-ish level, it was cold and I couldn't be bothered to take down the mast again to adjust so thought Ill leave it and sort out on Saturday and also thought because it is just wire why didn't I think to mount a pulley wheel on top and fix the wire to the pulley wheel with para-cord then I can just pull up and down like a flag on a flag pole to adjust for ease rather than dropping the mast up and down every time I needed to adjust.

So I pulled the mast down mounted a pulley wheel and threaded the para-cord through and attached that to the top insulator of the wire dipole and did a quick measurement of both sides and altered by about half an inch on both ends by folding the wire back over and twisting it on itself then hoisted it back up and came up with the idea instead of lashing the bottom insulator of the dipole to the mast I would just run the bottom line through a loop and attach a sea fishing weight to keep the wire taught allowing flexibility in the system with a view that later I would have an experiment of transferring the bottom out over to another structure creating a sloping dipole and the idea of the fishing weight was to keep it taught but allowing for movement in the mast in the wind so as not to snap the wire.

The thing is when I checked the SWR it was down to 1.5 which I was pleased to see thinking well its going the right way but due to grandchildren coming round and starting to snow I didn't have time to do any more adjustments but noticed on listening in there was a bit more background noise than previously and less signals coming through and in particular one user the night before I was listening to was radio perfect but after adjustments I could just say hear him which I thought weird as if anything I would have thought things would be better results across the board with the SWR coming down, I cant help think I've made a mistake somewhere but will try to bring down SWR further today but any ideas anyone as to why this would happen?

Any advice appreciated.

Dragonfly
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Sun Feb 02, 2014 1:55 pm

Atmospheric noise will change from day to day and even hour to hour , from around 8.20 each morning Olga arrives ( Rusian taxi operators ) and fades away after lunch time . Give the 1.5 SWR a chance for a few days and try some contacts as 1.5 is fine as it will not overdrive your radio outputs .

lorry
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Sun Feb 02, 2014 4:11 pm

Thanks for the advice, Update: I lowered the dipole for adjustment and noticed by accident I had swapped the top end to the bottom, the top being the length of wire the inner core of the coax is soldered to and the bottom being soldered to the wire shroud ( but also read somewhere it doesn't make a difference which way up it goes) I swapped them back around and it seems better although I didnt adjust the length the SWR the same at 1.5 then went back out and un-clipped the bottom of the dipole from the mast and tied it out from the mast at about 40 degrees and came back in and the SWR has dropped to 1.1 without any other alterations.

Ill see how it goes.

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porky.69
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Tue Feb 04, 2014 7:41 pm

nice one 1.1 is very good :D

greatwindowsss
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Thu Apr 16, 2015 2:20 am

I'm also new here and I'm looking forward to learn from you guys.

whats the best homebase antenna?

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