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h.brew cubical quad,2,3 or 4 element w/pics

johnny9 said:
wow i like it,,i think i totally get it now..the 2 outter screws on the block go all the way thru and the coax and wire go on the 2 sides.
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That's exactly right. Those are just the screw heads facing you and they go all the way thru the block where the coax/element attach with ring terminals and nuts.

johnny9 said:
other screw looks like a "set screw" to hold the spreader still in the hole?
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Yep, back that screw out, slide the spreader through the center hole and lock it in place with that clamp screw going in the other end toward the center hole.

johnny9 said:
i was worried about weight on mine..i have some clear lexan plexiglass thats 1/2 thick iirc,,it should work and would be much lighter weight.
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1/2" should work, especially if you have a drill press and can stay square enough to not bust through the side. I think they are only #10 SS screws.
 
as you can see by the age of this thread im in no hurry:D
thanks for sharing your great pics and knowledge,and i will be using it when i get more time to play with it..thanks,j9
 
I'm not seeing anything here that transforms the unbalanced coax to the balanced load the loop presents. While some would argue the loss created by this is small enough to ignore, there is more than loss to consider.

If you're running any power into this antenna it could cause significant RFI problems as a result of coax radiation. I would at least place some good ferrite beads around the coax at the feedpoint to get some of this RF off the shield of the coax.
 
Shockwave said:
I'm not seeing anything here that transforms the unbalanced coax to the balanced load the loop presents. While some would argue the loss created by this is small enough to ignore, there is more than loss to consider.

If you're running any power into this antenna it could cause significant RFI problems as a result of coax radiation. I would at least place some good ferrite beads around the coax at the feedpoint to get some of this RF off the shield of the coax.
Click to expand...

I bought a stack of beads and never used them because I was afraid of them heating up and causing issues. My final amp sits right under my laptop and my feedline runs along the wall behind an old 19" CRT color TV that I watch sometimes and I've never had any RFI issues. My wife never sees any issues downstairs either.

Oh, and my audio equipment wouldn't be considered RF friendly either I wouldn't think.
 
All of that is definitely a good sign but the direct connection of coax to any balanced antenna will always generate some CMC on the coax braid. How severe the problem shows up is dependant on many other variables. These include things like the length of coax used and the route the coax takes from the antenna to the rig, type of consumer electronics used around the area and its proximity to the CMC radiation.

We sometimes hear about people who have installed the cores on coax only to find they have burned through the coax causing permanent damage to the cable from too much heat. The first thing that we should consider when we see that is that there is significant CMC present, otherwise heating like this could not occur. That should not be ignored.

When that much CMC is present and the cores burn through the coax, you are either not using the right core material or not using enough of it to prevent core saturation and loss of permeability. Can't find the right core material? Buy a 1:1 balun used for dipoles. The type that just has ferrite cores on the coax placed inside PVC pipe. Use it as it is or even better, take two apart to rob the cores to put them directly on your coax.
 
I know what you're saying Donald, that's why I bought the beads in preparation for the install. But then I started reading about the heating issue and chickened out at the last minute and decided to try it without. That's been 3 years ago now.
 
90 percent of everyne here def knows more than me about this stuff no doubt.
but i will say my coax is 30 yrs old or older rg8 6-7 strand center,and i have another 100 ft on 35 yr old on standby lol..
my swr,s with the 45 yr old astroplane is dead flat,so hopefully does as well with this quad.
as of now i earned i dont have to have power,just the radio is doing a great job
"rci 2995dx"
my buddy has 4-5 antennas all homemade and has no issues either but if i do i will learn about what you mentioned and do it up right.
as of now from my antenna i will use 7ft 8 and a 1/2 inches of rg11 for feeding the qaud,then stepped down to rg8 old,hard as a rock coax that i have.
my buddy has the same exact measurement on 2 of his quads"vertical and horizontal" and has flat swr.s with his 3 grand yaesu radio and he talks to people that i cant even hear at all lol..i talk all over and it sucks when he talks to someone close or distance that i cant even hear a trace of is why im doing this quad like his..both his are 2 elements and he talks anywhere he wants at any givin time,almost..
im doing 2 for now but will step it up to a 3 element shortly after to see if it makes much diffrence;)
 
id like my tower to be further away in a better spot..is there anything wrong with running this coax at this length?
250 ft RG 11 Coax Underground Cable | eBay

for some reason i remember hearing to only use rg11 at the feed then rg8 from there back into the shack?
another words i have a 100ft run now..if i stepped up to a 200-250ft run of coax would i have a lot of loss and shouldnt do it?

id rather have the tower kinda hidden in the corner around some trees,instead of shining so brightly when cars come down the road where they can all see that cute lil astroplane..
boy it will really be the talk of the hood with the quad on it..

will 250 ft to the tower really not be a good idea? or can i do this? seou doems like rg11 would be smaller than the rg8 i use but i really dont no,,please tell me if you do :)
theres also lmr400 that i see a lot of folks use..i need to learn before i make costly mistakes in the future.
 
You can't use 75ohm cable for your run. You need 50ohm cable and then a quarter wave matching section of 75ohm in series to the antenna.
 
whats the best affordable cable for 200ft run? lets hear opinions please? if im gonna loose a bunch then i will stay with 100ft but really wanna go further away from the house.

my matching cable wont be 1.4 wave but will be 7ft 8 and 1/2 inches of rg11;)
its been up for my buddy for 10 yrs with no issues on a 2 element.
 
I wouldn't use anything less than lmr400 for a 200' run.

What frequency is this 7'8" stub being used for?
 
freq 27.4

he tried it with 50 ohm coax and didnt work to well.
i just asked him a few min ago and he said he is using rg6 75 ohm with a 18ga center conductor:eek: on both quads he built for 10 yrs now..very low swr.s..and at times he runs 800 watts thru it and can run more but he dont.said never had a problem yet.

rg11 is best for the matching system from what im learning from him but he has a 1000ft roll of rg6 so its what he used 10 yrs ago.but recomends the rg11 for me.

im gonna go with the rg11..the closer i think im getting the futher it becomes:bdh:
but id rather learn and do it right the best i can the first time..

now im stoped again because where i want the tower and my buddy says he can get lmr400 for just over 50 cents a ft..i need to find out hwere its that cheap..and all copper of course;)
 
The DB said:
In that situation I would give some serious thought to parallel feedline myself.


The DB
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I'd love to run that stuff, only if it'd handle some power.

I'm running 200' of cable too, although some of it is gathered in the attic. I could lop off 25-35' maybe, but it wouldn't gain me much and if I'd ever need it I don't want a splice. So I just run it.
 

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