Am I asking for trouble?

[loosecannon]

Hi all,

i finally got my telescoping fiberglass mast sections from max gain systems, and plan to put my astroplane up to about 40 feet at the top tip.

the fiberglass mast will not run all the way to the ground, it is 24 feet long and will be attached to the eves of the house at the bottom.
ill be using dacron rope for guy wires, but that's beside the point.

so, my plan is to run the coax right down inside of the fiberglass tubing in an effort to keep it out of the sun which is the most brutal element on coaxial cable where i live.

when the coax runs out the bottom of the mast (yes, i will be using ferrite on the coax 9 feet down from the hoop) it will run through white PVC sprinkler pipe down across the spanish tile roof (again because of sun and immense heat on those spanish tiles) and then tuck under the eave of the house.

from there the coax will be strung underneath the eave over to where the radio room is. no pvc on that part.

i plan to run the coax down to the ground, to a cushcraft lightning arrestor that will be connected to an 8 foot ground rod. ground rod tied in with house AC electrical.

my main question is will i be inviting static electricity on to the coax by running it inside the fiberglass tubing and then through the PVC tubing?

hopefully someone has some experience with the weird way i want to do this.
LC

 

[Handy Andy]

Does the "cushcraft lightning arrestor" does it use "shunt" or Spark Gap (Gas discharge tube)?

One type "shunt" is simply one large winding coil similar to a power choke for DC - Spark Gap ISOLATES the Coaxial conductors with a tiny air gap in a tube - so the arc would form thru an inert gas if lightning or a stray "stepped leader" were to ever use the roof of the home or your antenna as a point of reconnection if that were to occur. (Lightning Bolt - attaches to Stepped Leader forming the connection.

One being that the Astroplane is a Shunt type (DC ground) - your fiberglass "Sheath" design although novel, is not going to do much good in taming electrical noise. Static is in that list of "Noise"

Do you have another path to DC ground it?

 

[Road Squawker]

Perhaps I don't understand the question.
White PVC is transparent to RF

Grey and black PVC has bits of metal mixed inside and will affect your Tx/Rx.

 

[loosecannon]

thanks for the replies.

the lightning arrestor is the Cushcraft LAC4H: http://www.radiomanual.info/schemi/ACC_rotator/Cushcraft_LAC-4_user.pdf

Road Squawker, im not too concerned about the RF flowing in the coax, just that static electricity that might be involved. i don't know.

Andy, im not putting the coax inside the fiberglass to lessen the noise, its to protect it from the sun.
however, yes, getting a bunch of static crashes in my receiver is not something i want.
LC

 

[Handy Andy]

Andy, im not putting the coax inside the fiberglass to lessen the noise, its to protect it from the sun.
however, yes, getting a bunch of static crashes in my receiver is not something i want.

That's what I was referring to.

The antenna is DC grounded, but your ground is back at the Arrestor. Quite a long length, and with lightning present or even static wind - the pokes and presence will always be there - the path is inductive length of loss not just for signal but the static will drown out that signal you want - at times - because of the losses.

Possible to Run Separate Ground Buss wire to down the Fiberglass sheath, on the side of the home, downlead to ground rod?

The static may bleed into coax, but at least the hazardous side of those voltages would be in closer proximity to the earth ground for the antenna. Because it will dissipate from the antenna thru the Ground Downlead.

 

[kopcicle]

Perhaps I don't understand the question.
White PVC is transparent to RF

Grey and black PVC has bits of metal mixed inside and will affect your Tx/Rx.

Easiest test, place a sample in the microwave. If it heats or melts it is no good

 

[Captain Kilowatt]

Easiest test, place a sample in the microwave. If it heats or melts it is no good

Just put it in the microwave with a glass of water as a load or you risk damage to the microwave oven. I have had no issues with using black ABS pipe but admittedly not at high power. The black comes from carbon black pigment and not actual metal flakes BTW. Not all black plastics contain carbon black.

 

[357magnum]

WOW ! Okay , now my head is spinning ! But now I get it after reading this thread a few times . More info I learned from WWDX . Thanks All from this " Dumb Swamp Yankee " . Stay Healthy & Safe ! 73 & God Bless ! Leo

 

[loosecannon]

I guess the question to ask is, is there any difference in running your coax down the side of a length of fiberglass as opposed to inside it?
I suppose a phone call to max gain systems is in order.
sure appreciate the discussion.

Andy, the reason i wouldn't want to run a ground lead down in this particular case is that the whole point of this idea was to get the antenna up in the air completely isolated from its support structure, and be able to choke off the common mode currents at the closest possible spot to the feedpoint.
It's all about the unique design of this antenna and many past discussions with people like Marconi and others. (Marconi im forever grateful for all the modeling you did)
LC

 

[HomerBB]

It won't hurt anything to run coax through fiberglass and PVC tubing. The gainmaster antenna is an example of coaxial cable running through the interior of fiberglass tubing. Seems to work just fine.
Now, it will hurt your feelings if that mast falls down and breaks you antenna. I hope that beside the point dacron rope keeps that lightweight mast erect!
Pictures, please.

 

[loosecannon]

LOL Homer.

thank you so much for sharing that.
I hadn't thought about the gain master, and here's the real embarrassing part, i just watched that homebrew gainmaster video Marconi posted!

im going to use 3/16" rope, and ive used it before and had good luck.

i imagine you've used the max gain tubing in the past as well. i found it to be sturdier than i expected.
i will absolutely take some pics.
LC

 

[bob85]

LC id be more worried about the noise I would pick up from my own & neighbors houses running coax above ground than a bit of static,

the leg diameter & spacing on the avanti astroplane gives the best vswr match when the conductive mast inside the antenna is 1.5" diameter aluminum,

you will find out if the skinnier copper coax with jacket & dielectric loading from the mast changes it too far from spec & needs tweaking for best vswr.

good luck.

 

[357magnum]

I've said this in the past " Marconi My Antenna God " ! He's my go to , but we have others on here . It has nothing to do w/me this time , but thanks Marconi for coming thru w/ help for our Good Friend " LC " ! Stay Healthy & Safe ! 73 & God Bless ! Leo