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Inverted V diple question.

BillV

Member
Jun 24, 2011
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0
11
I have 10-80 inverted V dipole, and was wondering if the bottom of the ends have to be at an exact height off the ground as the tree I have at the one end wont let me do that.... and I want to attach it to a different tree for a different orientation, but cant go the exact height the antenna manual says it should be at. So is it a critical height?


Thanks much

Bill :headbang
 

RatsoW8

Supporting Member, W9WDX ARC Member - WD8T
Nov 3, 2009
3,102
1,402
273
West Central Michigan
If you have room for a 80 meter inverted vee you can put up a resonant 40 meter vee and tune with an antenna tuner it for higher bands. That's what I would do. Unless you're craving for the 80/75 meter experience.

If not, just put it up best you can, use a tuner and start talking.
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,405
1,269
173
Height is not that critical but safety is. you would want the end of the wires high enough above ground so no one can touch them for safety.
 

doctor

Supporting Member
Aug 1, 2006
1,036
79
58
79
indiana
inv

I have one and use it for 75...I run my height<ENDS OF THE ANTENNA> no more than 4 to 5 feet off the ground and use a antenna tuner..works like a champ, so raise it the best you can as long as it doesnt touch the ground..by the way I tie it off using bungee cords hooked to fence post..
DOCTOR/795
 

ElectronTubesRule

Active Member
Sep 6, 2011
257
15
28
I second the saftey of keeping it high enough so kids and stupid people do not try and touch it. From about 500watts on up you can get some burnt tissue from RF energy. I once had someone not believe me so I keyed my then 667 and they touched my 102 inch whip. It left a burn mark on their hand for about 1-2 hours just a mild welt but that was just 500Watts image having legal limit going through that wire and a little kid or a dog or cat touching it! So do make sure you keep things safe. Most people do not see a dipole and then say "Oh that might have huge amounts of RF energy radiation from it I should stay away!" no instead they walk over to it and want to touch it and examen it! In fact peoples lack of common sense has been used for years int he construction of boobie-traps like kick the can and American Gi's or placing a bright piece of fabric in one place so you are not looking in front of yourself and walk into the trap etc....Humans are curious by nature so keep it out of the reach of kids and stupid people!
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,880
11,088
823
59
Nova Scotia,Canada
FWIW even 100 watts can generate quite a high RF voltage at the end of a quarter wave. I remember the time my parents came to visit us in our apartment just after I was married. I had a pair of phased (NOT CO-PHASED BTW:whistle: ) 1/4 waves on 10m set up indoors with a small neon bulb at the top. dad was curious as to how I kept lighting it up. When I told him about the RF voltage he didn`t believe me. I said `Run your hand up the antenna while I key up". I made a believer out of him. :LOL:
 
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ElectronTubesRule

Active Member
Sep 6, 2011
257
15
28
I was at a gas station meeting up with a bunch of guys from High School. When I would key up the florescent bulbs of the closed gas station would light up when I keyed. Their must have been 8-9 bays with 4 long florescent bulbs in each one. They would come on when I keyed up then a few seconds after I unkeyed they would go out. I tried to explain to one of the guys that it was the RF energy from my amplifier that was exciting the gas in the bulbs. I had previously that evening had him stand away from my antenna which was on the bumper of my 4X4. I had no idea how much energy he was getting but I figured it was not a good idea to sit close to a whip with 500 watts coming out of it!

So being the idiot he was he decided he was going to hold on to my whip while I keyed to prove me wrong. I said something to the effect of "If anything happens it is all you with plenty of witness's!" I keyed up I do not recall if it was like 2 seconds of 5 seconds but I know I remember him pulling his hand away in what looked like a hurry in my "Objects and idiots are closer then they appear mirror on the passenger side of my truck!LOL

I was surprised because I had no clue what effect it would have but for about an hour or two you culd see and feel a welt on his hand that matched the taper of my radio shack 102 inch SS whip. He kept a ready supply of cold beer in that hand for the night so like I said after about 2 hours you could not even tell it had bit him!

It was funny though only because it did not cause any serious injury. When I was a Union Electrician in and latter in Telcom industry we had to watch safety video's at the beginning of any training....It never failed they would have some one that had tried to climb a broadcast tower and you would see what looked like a massive exit wound from where the RF energy exited the body. Imagine an unvented hot dog over cooked in the microwave with charring around the edges of the explosive eruption out of the body. Then they would have a guy that got zapped by high voltage transmission lines like the ones that link sub stations or different parts of different grids together.....If they where lucky they only lost their arms. So while I am not a fear monger I do not play around with electricity like it is a toy for my amusement or with fire or any other powerful and useful tool. The second you do not show some respect these things will bite you but one should not live in fear either you have to have a healthy balance of respect and comfort.

I have never since that day allowed anyone to touch any of my antenna's while they are live no matter how ignorant and stupid the person wants to be! I am not going to give a person the tools to harm themselves not if I am going to be liable for their stupidity!

Did you know that early on in radio technology scientist found that Hams did not get sick as often as most other people.....Later on they figured it out they where getting enough excess RF exposure to raise their core temp a few degree's this was keeping them at a lower bacterial and viral load. This is before they know much about high energy radiation and such and it's effects on living tissue. Some of these guys int he photot's I have seen had dipoles hanging like 6 inch's above their head's inside their room. The extra RF energy was also killing bacteria and virus inside the room again reducing their exposure.....I wish they would show that documentary again it was on late at night on one of the History or Discovery Science Channels and it was about the early days of radio. I have only seen it that one time in my life if I see it again I will try to get the name so we can maybe get a copy of it!
 

Captain Kilowatt

Professional Amateur
Staff member
Apr 6, 2005
16,880
11,088
823
59
Nova Scotia,Canada
My "favourite" recollection of RF burns was when I was working on a tower lighting choke that isolated the AC power lines from the RF on the tower. The AC power flows thru these chokes to the tower lights and in this case the tower was being fed with 10 Kw of carrier on 960 KHz. That's 40,000 watts pep with modulation. The AC power was turned off and as I started to work on the lighting choke I found that the RF bypass capacitors were shorted and in effect were shunting the RF directly across the choke. That burn hurt for two weeks or more and was visible for months. :cry:
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,405
1,269
173
RF what a wonderful thing.

I would go out land clearing in my younger days ( four wheelling in the mud holes). After all was said and done then it was time to clean up the truck.

Drive to local car wash, park in the bay, turn on the radio, Key the sweet sixteen amp and the car wash relays would engage and I would get a free wash.
 

ElectronTubesRule

Active Member
Sep 6, 2011
257
15
28
Waverider I used to do that too!!! How funny....The ones I used as long as you had about 500watt's it would cause the car wash to activate. I never told anyone about that I always felt guilty because it was in esscense stealing services! Living in the Coastal Ga. at the time all of us went Wheeling all the time! Beer, Girls in short shorts or bikini's, loud music, cb radio's and lots of pond crossings and mud holes and fallen tree's to get over. LOL It used to take $16 worth of quarter's to get all the Red Clay and such out of the mag wheels and out from under the hood. So a 667 was cheaper in the long run then spending $16 every time you went wheeling to get clean! LOL

Small World.
 

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