Antron 99 install loads of noise

Hello all

I’ve just had an Antron 99 with the Firestick top section installed but I’m getting a constant signal level 5 on FM & AM and 7 on SSB of noise.

The antenna is mounted on an 18ft pole about 10ft above my roof line.

The only thing I can think of that’s causing the noise is that the coax comes out of the antenna, has a drip loop and then is fed down the metal mounting tube (18ft) for cosmetic reasons.

The SWR is is good so do any of you in the know think the coax running down the mounting tube will give me the undesired noise?

Hi Mic,

Noise or QRM is the bane of many a radio operator but fear not....

Many tend to "crank it up to 11" when operating their radios and you'd be surprised of how much you can reduce the background noise by simply turning down the RF gain. It seems counter intuitive but it reduces all that hash noise and is surprising how much clearer signals come through using this method.

The other thing to maybe address is Common Mode Noise. (I know, we never had to think of this stuff 'back-in-the-day' but there wasn't all the QRM inducing electronic junk around either!) This can be much reduced by use of a Common-Mode-Choke.

To make a cheap and effective air-choke you can simply wind five turns of your coax around a 100mm former the most commonly available material being plastic soil pipe that you can pick up from a DIY store or trade outlet.

This comes from the great work of the late Steve Hunt (G3TXQ - SK) with a link to his work here :-

http://www.karinya.net/g3txq/chokes/

(Take a good look at the graph for details.)


Hopefully winding yourself such a choke should reduce any common mode problems and hence noise but do remember that noise levels come and go depending on propagation. You've got nothing to lose by winding a bit of your coax in such a simple way and see how you fare.

(Some just loop up a bunch of coax in an open coil but it's a bit hit or miss so worth seeing if you can get a short bit of pipe and do it properly....or even later delve into the 'mysterious' world of ferrite materials. )


I hope you get sorted.

All the best,
Victor

Hi mic. I just wrote a post that literally mimics what Victor just wrote, so scrapped it.. just read his  

Would just add that you could try a bit of noise sourcing in your own home to see if there is anything you can eradicate. If you can set up your rig on a battery and turn off power to the whole house, see if that reduces the noise. The power bits on one by one to work out if the noisy culprit. If you are like me then most of my noise is from neighbours unfortunately, but you might strike lucky and find something in your home you can sort.

Thank you Victor and SangueG for your replies.

Yes I’ve considered making an Ugly Balun.

I’m repositioning The whole installation later this week from the side of the house to the rear as one of my neighbours has complained so that will be the ideal opportunity to put an RF Choke in place.

Do you think running the coax down the inside of the steel mounting pole is causing me noise though? Is it best practise not to do that?

I’m also going to install the ground plain kit for the Antron 99 as have been advised to by a local Ham as this area is a bit of a Black Hole as far as signals go.

Comments welcome.

There is a thing called a 'sleeve balun' where the feed coax is slipped through a metal section at the antenna and is common on VHF/UHF antennas. (My homemade UHF beam sports one.) I'd presume it must have some sort of effect even at HF especially with such a metal long pipe but as I've never performed such I couldn't really comment. The only real way of knowing is to see if any difference is observed on either installation. (I've always placed the coax outside of such mountings.)

As for ground plane kits, some swear by them whereas others condone them stating that they made no difference. (It's a must for a 1/4 wave antenna though to make up the other 'half' of the antenna.) Up to you in the end really and this is probably why antenna discussions end in heated debates. You can study theory until you're blue in the face and unless you have some practical backing for your very self you can never be absolutely sure. Two people could put up exactly the same antenna setup and disagree to it's performance, but then is it 'exactly' the same (surrounding buildings, location, feeders etc.) and are they expecting the same results?

For me that's the very example of having fun with it all, by finding out for yourself. 

I have an antenna system that most would condone yet I achieve the results I desire with what I have available to me. In my opinion a 'compromise' antenna is by not having one at all, otherwise enjoy the merits of any antenna system you can happily piece together.

(There's still always that flipping itch though of whether something else 'might' be 'better'. )

Have fun.  

73

Can't really add much to what others have already said.

Assuming you realise that all the HF bands are noisy at the moment, and you have or will try what others have suggested, there are two things that I might add.

At the antenna end, electrically bond the coax outer to the metal pole, then add one or more 1/4 wave ground plane wires that hang away from the pole. These can be very thin so as to be almost invisible. Physically earthing the coax and/or the pole might help too.

If you decide to feed the coax outside the metal pole, you could wind an RF choke in the coax 1/4 wave from the antenna to act as a 1/4 wave ground plane.

To be honest, antennas never work the same in different locations. Experimenting is a big part of the hobby.

Deb