Mast material

[hfxChris]

I tell you, I'm having more problems with this antenna I'm putting up.

So I've decided to mount a mast onto the top of my clothesline pole. Nothing huge, maybe an additional 5-6' beyond the top of the clothesline pole, which is already quite tall (maybe 15').

So I head into Home Depot today and look at metal conduit, and galvanized metal water pipes. I even brought the base of my discone with me to try fitting it on various diameter poles to see what fits. Well wouldn't you know, nothing does. The 1" conduit is too narrow. The 1 1/4" is too wide. But the 1 1/4 is just a little bit too wide, if I could shave it down a bit it might squeeze in... and the 1" is just a bit too narrow.

So, anybody have any suggestions? It looks like I'm going to need something 1 1/8", but couldn't find anything there. Anyone have any luck grinding down metal conduit, or possibly have any suggestions for building it up at the end if I go with the 1"?

 

[K8PBX]

Sounds like you didn't get the mast clamps with your discone, as shown in the pic below?

 

[hoser147]

I was just adding an antenna to my tree I used a piece of 3/4in conduit. It too was to small I added a 90 to it( the one that has the access hatch) and it worked good just good enuff to clamp the small dicone on to it. Worked out fine. Maybe if ya look at the different fittings and connectors you can find something to do the job. Just take out the screws and run a self tapper in there to make it solid.....I just was using what I had around.......Hoser

 

[DPD1]

Are you trying to put the bottom tube of the antenna inside another tube? If you don't have any mount hardware, just get a couple stainless band clamps in plumbing. Check out the different rubber hose sizes and you can get a piece of hose to go over one tube or the other, just to add some insulation. But they should also have TV masts in the TV section.

Dave
http://www.dpdproductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist

 

[hfxChris]

Sounds like you didn't get the mast clamps with your discone, as shown in the pic below?

I definitely did not! Shucks. All that extra stuff is exactly what I need...

hoser147, looks like I'll be taking your advice and make the best of it .
As I said, the 1" conduit comes close, there's maybe 1/8" of play that I would have to do something to...although now that I look at the antenna base, the screws that squeeze into the mast do go in quite a ways, so I might just get by with the 1" conduit...

 

[hfxChris]

Are you trying to put the bottom tube of the antenna inside another tube? If you don't have any mount hardware, just get a couple stainless band clamps in plumbing. Check out the different rubber hose sizes and you can get a piece of hose to go over one tube or the other, just to add some insulation. But they should also have TV masts in the TV section.

Not quite sure what you mean about bottom tube of the antenna...

I'm attaching a picture I just took of the base of the antenna. This is going on top of the metal conduit I'm purchasing, and the metal conduit is going to be either clamped or bolted onto the side of the clothesline pole, near the top.

 

[NoRide]

It would be easy to open the i.d. with a lathe but that may not be an option for you. Set screws won't take up the slack of a 1" tube?

 

[DPD1]

I've never seen anything like that by itself. I guess the set screws tighten around the tube. Weird.

Pipe size goes by the inner dimension. Tube size goes by the outer dimension. Measure the inner dimension of that flange and go to the nearest metal dealer and look for tube that has the same outer dimension. Sometimes they have remnants so you don't have to pay full price. Aluminum would be good. Seems like it's missing something though. I think it should have come with a length of tube to go in there to begin with.

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist

 

[NoRide]

Dave, I think this may be the style or similar Discone antenna Chris is using.

 

[hfxChris]

Indeed, that looks like it (once the radials are attached)

Set screws won't take up the slack of a 1" tube?

They should, but I'm not totally sure. I didn't have an allen key with me at Home Depot to tighten them (not even realizing I was in a home improvement store which probably sold allen keys ). Guess I should try that.

 

[DPD1]

That's a pretty logical design. I actually considered doing something similar with our verticals, but I worried that people might have a hard time figuring out how to mount it, or what materials to buy. Guess I was right. ;-)

Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist

 

[hfxChris]

Oh absolutely. I didn't realize most discones don't come this way when it arrived, I just assumed this was the norm. It does make logical sense why they would do this, but it makes no sense why they made the opening an unusual size like 1 1/8"

For the record, the package says it's a Workman T-601, purchased from Durham Radio in Canada.

 

[hfxChris]

Well I actually brought the allen key with me to Home Depot this afternoon, and tried it again. The set screws are indeed long enough to hold it onto the 1" diameter conduit very tightly! Perfect, looks like I've solved that problem.

Now I've just got to figure out how to pound a 10' ground rod through bedrock...

 

[hoser147]

Hey Chris, what's your clothes line post made of ?? How is it in the ground?? Hoser

 

[hfxChris]

Hollow metal pole, concrete base, maybe 3-4' underground...

 

[hoser147]

There is your ground my friend. Good Scannin Hoser

 

[hfxChris]

Would that actually work? I mean it only goes down 3-4 feet... do I just connect the lightning arrestor on the coax to the clothesline pole?

 

[hfxChris]

Anyone know? Would the clothesline pole actually form a decent ground?

 

[OceanaRadio]

Anyone know? Would the clothesline pole actually form a decent ground?

Yes Chris, a metal pole in a concrete base 3-4' deep will provide much more highly conductive surface area than the additional 4' of ground rod you would otherwise use. Ensure there is no insulator between the antenna base and the mast.

Recommend you route the coax in a shallow trench to the AC entrance ground rod, shield-ground it by placing the arrestor there, then proceed into (or under) your home to the radio area. Since the run may total over 100' to do this, you will want to use low-loss coax such as 9913 or perhaps less expensive RG-8. One section from the mast to the AC entrance ground rod and arrestor, the next leg to the radio or active multicoupler.

You will then have a safe and productive antenna system.

Best regards,

Jack
Virginia Beach

 

[hfxChris]

Thanks for the great information. I really wasn't looking forward to pounding it through solid bedrock

The location where the antenna going and where the cable is going to enter the house is already a good distance, so I'm already lining up some LMR400 cable.