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Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1429
Registered: 9-2004
| | Posted on Thursday, April 13, 2006 - 10:47 pm: | 
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with the sunspots fading, so is my desire to raise my CB antenna to its utmost capabilitly. dont really care how well the locals hear me, and i will have moved by the time the upswing starts.
so, i have a mast up already that is about 30' in the air, and i dont mind adding 5 feet to it if need be.
i would like to put up an inverted V design, and i would like to build it myself.
since my ticket is not current; i will only be listening on a shortwave radio for now. (hence the no tuner clause)
i want the antenna to be 80-10 if possible.
what are my options?
thanks for any ideas,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1307
Registered: 8-2002
| | Posted on Friday, April 14, 2006 - 10:44 am: |
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If you plan on transmitting, then length becomes important. However, for receive-only, the more wire the better. Feed it with a coax and a balun or just use open wire line all the way to the shack, either way.
Truthfully, for receive (and for TX on the lower bands), an inverted L will work better than an inverted V, and you can feed it with coax from ground level. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1434
Registered: 9-2004
| | Posted on Saturday, April 15, 2006 - 9:37 pm: |
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thanks paul!
i guess i was under the impression that if an antenna is tuned for resonance enough to transmit; then it would also be a more efficient receiving antenna.
but since i will be flipping the dial all over the place between .5 and 30mhz, this isnt really possible is it?
got a favorite length? im trying to stay less than 100' for the horizontal portion.
a 1:1 balun?
i will start looking at the L antennas online,
thanks,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1311
Registered: 8-2002
| | Posted on Sunday, April 16, 2006 - 9:43 am: |
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Favorite length?, No. However, my inverted L is 30 feet from ground to the elbow, then 130 feet horizontal, and I can hear EVERYTHING!
I have done inverted L's with 70 feet on the horizontal and about 25 feet on the vertical and they worked just superb.
For real high frequencies, length on receive does make a difference, but below 20 Mhz, not really. Especially when you get down past 5 MHz., the more wire, the better. BUT- NO COILS! Coils kill signal.... Except on CB if you ask some... |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1438
Registered: 9-2004
| | Posted on Sunday, April 16, 2006 - 10:40 pm: |
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thanks again,
i had some other questions but i guess the post didnt make it through.
1. i read that a 9:1 balun works well at the feedpoint. what do you think?
4:1?
2.i have a ground rod right at the base of the mast i will use for the vertical section, that is connected to my shack ground rod eight feet away from it.
a)should i connect the shield of the coax to this ground rod?
b)do i need to keep the vertical element a certain distance away from the mast? (metal)
i think mine will end up being 25' on the vertical, and about 50' horizontal.
any big probs with this?
im trying to keep the antenna oriented north and south.
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1313
Registered: 8-2002
| | Posted on Monday, April 17, 2006 - 11:29 am: |
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Answers.
1. I use a 9:1 on my antenna, and the SWR is below 3:1 almost everywhere above 5 MHz. For receive it doesn't really matter much. Don't sweat it.
2. Great. A- Yes. B- As far as possible.
3. No probs. An inverted L is very omni, so don't sweat the orientation much. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1439
Registered: 9-2004
| | Posted on Monday, April 17, 2006 - 11:34 pm: |
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thanks again!
i am ready to start my project tomorrow!
cool on not needing the balun; one less thing to buy.
omni you say?
COOL!!!
i was sure it was broadside to the element, i dont know where i got that from. (my own skewed logic!)
this means i can orient it in a more southeastern direction and gain about 20' or more on the horizontal section!
im guessing that the vertical section needs to be pretty much vertical, and not at an angle.
true?
this is going to be fun!
i have a couple of questions about the shortwave receiver i am using and the one i want to buy, but i really should start another thread for those.
would you mind taking a look at the thread in the "shortwave" section of "ask the tech", as its your opinion im looking for?
i will call it "questions for tech833, and anyone else"
thanks,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1318
Registered: 8-2002
| | Posted on Tuesday, April 18, 2006 - 9:45 am: |
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The vertical does not have to be perfectly vertical. Up to 30 or 40 degrees would still be O.K. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1449
Registered: 9-2004
| | Posted on Tuesday, April 18, 2006 - 9:48 pm: |
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thanks again.
i have an old military book on antennas from the late '50's that i love to referrence when doing a project.
i found the inverted L in there and sae that theirs had the downlead at a considerable angle.
(about 30*)
boy, there sure are alot of variations on this design eh?
they used a counterpoise under theirs, and it had removable jumpers for different lengths.
also really liked the "crowsfoot" antenna.
i put the antenna up today!
50' horizontal, and 27' down. fed with RG8u with the shield connected to two 8 foot ground rods.
one at the base of the downlead, one 9 feet towards the far end of the horizontal section.
it works great!!!
i always use WWV to see how well my hombrew antennas work, and this one was FULL SCALE!
thats two S-units of improvement over my "broomstick" antenna that was a four foot broom handle wrapped the whole length with 16ga. wire, and a 12" metal disc on the top.
this was on top of a 10' mast outside the radio room, and actually worked quite well.
the ONLY advantage the broomstick had over this antenna is that now i pick up HEAVY BCB inteference. like i cant use the first 5mhz heavy, with plenty of harmonics after that.
somehow, the broomstick didnt pick it up.
i live within five miles of the "sports radio 1460" antenna, and i also pick up another station but havent ID'ed them yet.
any advice on something i can build or buy to help with this?
thanks for your time,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1322
Registered: 8-2002
| | Posted on Wednesday, April 19, 2006 - 9:33 am: |
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Check your other thread. |
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