Thoughts on TV antenna masts....?

[VE3GZB]

I'm thinking it would be great if I were to make a 20m dipole, yank the unused VHF Yagi off the top of the mast and stick the dipole up there instead.

But I've got a few questions....

How heavy is a 35 foot tall 20+ year old TV mast? Could I just unbolt it from the side of the house and using two hands just tip it over and down?

Or

How much weight will a typical 20+ year old TV mast bear?

I'm not much good at heights and if it were not too heavy, tipping it over would be my preferred method.

I'd appreciate any thoughts on this subject.

Thanks and 73s,
geo VE3GZB

[Pete, WA2CWA]

Gauge of the metal, diameter of mast, aluminum, steel ??

[K5UJ]

I've had some experience with galv. steel push up masts that are made for tv antennas.   I have two 50 foot Tessos up now, that I reduced to 45 feet and 40 feet for better strength.  a 35 foot steel one extended will be too much for you to handle alone.   It is too long, tall and ungainly and you won't be able to control it by walking it down, even if the base is shoved up against something like a house foundation so it doesn't scoot away and swing up.   If it has anything on top of it, it might even buckle.   Each section is only in the one below it a few inches.  It is better to at least partially collapse it while vertical. OTOH, if you don't care about its condx and there is nothing near by you can give it a push and let it fall.  

When working with galv. steel push up masts wear thick heavy work gloves at all times.   They can be dangerous and if your hand gets caught under a guy ring while it is shooting into the section below, oh man, owwwwwwch--you will find out how fast you can get to cold running water

Just about anything is better than those push up masts--their one positive is low cost for height.

BTW, any wire you put up with one, be sure to have it on marine pulleys.  You do NOT want to ever have to take one of those masts down after you put it up if you can possibly avoid it.

Rob  

[flintstone mop]

Whatever you do use heavy duty gloves when working with this. If it is one continuous piece or two and not a PUSH-UP type mast then 35 feet will get away from you and could cause damage to your property or you.
A push-up mast can be equally dangerous if you're alone. I almost lost a finger when a section that was stuck finally collapsed and slammed the living hell out my finger. ALMOST chopped it off. Has to call 911 from the back yard......something made me carry the cordless phone out there that day.
The age you mentioned is going to be a pain because it is most likely stuck and will not cooperate.

[VE3GZB]

The antenna mast is assembled in 16 inch long sections which fit into each other. Not sure what you mean by Push up type (sounds like a bra??).

Hmm, I looked into the ridigity of PVC pipe, which is what I was contemplating to use for the legs of a dipole, just run wire within them and mount it all high up on the tower.

Not a good idea.....PVC pipe in 10ft lengths is rather springy. Assembled to the needed length of 10m, it would flap like a bird.

So the notion of mounting a dipole for 20m QSO has to go on hold for now until I can figure out something better.

I have a pair of filters on order in the mean time, one for the TV and one for the transmitter. Imagine what it would look like if I got them mixed up! LOL!!

Until the filters arrive, I'll stay off the air. I hope the TX filter doesn't affect DX, I had a surprising QSO last night with an LA5 way up north!

Thanks and 73s,
geo VE3GZB

[K5UJ]

The antenna mast is assembled in 16 inch long sections which fit into each other. Not sure what you mean by Push up type (sounds like a bra??).

Heh heh, you're not sure what we mean by push up pole?  Well i'm not sure what a mast with 16 inch long sections is!   maybe one of those chrome whip antennas on a Trans Oceanic?   

BTW a "push up pole" is just what the name implies--a mast, usually made of cheap thin wall steel tubing that has been galvanized, with 10 foot sections, each one fitting inside one of slightly wider inner diameter.  They telescope up, the inner one first, with each one locking into place with a pin and set screw to hold it, a bit inside the wider one below it.  You put one up by mounting it all collapsed first, then get up on a ladder and push up the sections until it is all extended.  Each section is guyed.  You have to push it up on a still day and quickly run around guying it before it blows over.   So obviously you have to have your guy anchors in and the guy ropes or wires cut and attached to the guy rings at each level. 

You used to be able to get them for heights from 20 to 60 feet.  The 60 footers were pretty insane.  Rohn made push up masts with the model no. H20 to H50 (not sure if they made 60 foot ones or not but you used to be able to get them from Radio Shack).   They are all getting hard to find and are not in my opinion missed very much.  The lower ones, 20 and 30 feet were not too bad, but the higher ones are kind of a b**ch to put up because you'd usually get one section that was eccentric and it would bind.  Because of the length collapsed, they would have to be shipped on a truck and they'd get banged up.   So it takes some upper body strength to push one when you are on the last lower section and have all of the higher ones resting on it.  Start weight training now hi hi.  But properly installed, they can take a lot of wind and hold a wire no problem.  The tall ones just have a hell of a lot of guy cables. 

[VE3GZB]

Yea, then it sounds like the mast I have here is a "Push up" type. Didn't know it was referred to as that!

73s, geo VE3GZB, temporarily off the air until my low pass filter and new tuner arrive so I am at less risk of causing TVI.

[n2bc]

Tipping it over fully extended will give you a pretzel.

Field Day experience:  Well meaning fellow brought 3 20' lengths of ABS well pipe.  Good stuff, strong but light weight, threaded connections.  His idea was for an inverted vee support.  I smiled as he tried to raise all 60'.  He got his end vertical, but there was a giant horseshoe and the other end and the antenna were still on the ground. The stuff is made to be in tension, not compression. 

He had the last laugh tho, he also had his hot air balloon.  He indeed got all 60' vertical, but I think that was cheating!

[VE3GZB]

!!LOL!!! Thanks for sharing!! I don't need no pretzel antennas!

[flintstone mop]

I don't think the Low Pass Filter is going to do any miracles.
How close is the TV antenna to the Ham antenna?
Can you explain your interference problem for the TV?? We're assuming Over The Air analog TV or Digital??
You may need to separate the TV antenna farther from the Ham antenna. Fundamental overload. Too much RF getting into the broad-as-a-barn-door tuner in the TV.

Fred

[VE3GZB]

TVI occurred only while I operated on 20m, not on 40m.

I moved the antenna about 30 feet away from the incoming Cable TV Coax but I'm still causing some TVI on 20m only.

73s
geo

[flintstone mop]

TVI occurred only while I operated on 20m, not on 40m.

I moved the antenna about 30 feet away from the incoming Cable TV Coax but I'm still causing some TVI on 20m only.

73s
geo

OK Geo sounds like an old cable TVI problem. You will need to buy or make a common mode choke for the cable TV problem. They are available online. Folks here will boo hoo buying, but better than making one.
Your RF is coming in on the shield of the Cable TV Coax and trashing the box / or TV............your probably using RF Chan 3 to the TV?

This link is pretty informative to build common mode chokes. The guy really likes chokes. Nothing mentioned about Cable TV chokes, though.....I'm looking.....
Common mode PDF
http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf

And here is some good info from the ARRL. There are illustrations showing construction

http://www.arrl.org/cable-television-interference

Geday
 Geo

[VE3GZB]

Yup, that's what I kind of figured too.

From the same place I get the tuner, I ordered this TV filter:

http://www.durhamradio.com/vectronics-hpf2-high-pass-tvi-filter-whitby-ontario-canada.html

I also ordered a LP filter for my rig:

http://www.durhamradio.com/vectronics-lp30-low-pass-filter-ontario-canada.html

Hopefully they'll arrive this week and I can put them on.

I'm wondering if I have to put the TV filter directly on the TV or can I just put the filter onto the Cable TV Coax where it enters the house, because there are 3 cable TV Coax feeds in the house.

73s geo
VE3GZB

[flintstone mop]

YUP Geo
You should be good to go. Cuz I read description and see the words common-mode for that TV filter and you should be FB OM!!!

[VE3GZB]

QSL. Tnks, 73s de geo VE3GZB

[K5UJ]

all you have to do to make a tv coax CM choke is get two 75 ohm to 300 ohm baluns and chain them end to end so the balanced feeds are connected to each other then insert it in the coax line.  I bet if you buy one you get a pvc pipe with F jacks on the ends and inside is two baluns backed up to each other.

I guess you could call it an unbalun, or unbalbalun hi hi.

rob

[KB2WIG]

   He said  'ridigity' ....................


klc

[WB6NVH]

That's exactly what I did when I was 12 years old - - put my inverted v for 40 Meters at the top and one for 20 Meters spaced below it after taking the TV antenna off. Yes, there were various disadvantages, which I didn't know about because there was no Internet and no forums.  I just put it up and had a lot of fun working stations all over the world.  I seem to remember the thing was corroded into one piece but it went up that way without issues and I only guyed it at the top of the first pole.  An inverted V isn't much of a load at the top.