Radio Antenna On Chimney ?

[Bill]

In message , [e-mail] writes

Crows can be a radio engineers best friend too.

I had a PMR base on a site with a 100 foot tower in Nottingham and the customer complained of intermittent poor range. I went up there twice and checked the base and the aerial were OK. The aerial I swept from ground level and it checked OK. On the third visit I was getting the same results and beginning to suspect foul play, the customer had a few enemies and had in the past had his system jammed. Any way all of a sudden the aerial showed a fault for a couple of seconds, this happened

2 or 3 times in quick succession. Standing in the doorway of the site hut and looking up a crow was perched on top of the aerial and every time it took off the aerial, 3m long fibreglass tube waved about. I thanked the crow for its help and ordered a new aerial.

On the subject of chimneys I would go for

it is more expensive but will withstand the loading the OP has in mind with no problems at all and although it still has only one lashing wire it has more metal against the stack and will be less prone to twisting, not that the first one mentioned probably would either. But this definitely would not.

Within reason try and get the aerial as high above the chimney as aesthetics will allow, this will give a better take off, especially if you have neighbouring chimneys and roofs near by.

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[zaax]

How do you work that one out? I would prefure to repair a window rather than a chimney.

[Huge]

That would be a first ...

BTW, I've had a 2m folded dipole on a chimney for ~15 years, using a standard TV lashing kit without any issues (at least relating to the mounting - the UV hasn't been kind to the plastic parts of the aerial.)

[dennis]

Yes, after I posted.

Doesn't anyone in this group know that usenet is an asynchronous mechanism.

[dennis]

How would you know, you appear to know nothing about anything, all you do is assume geoff is correct which is a big mistake on anyone part. I think you, geoff aand drivel are the same person.

Well if you go into the car park at the doctors surgery at #6 High Street, West Bromwich you can have a look at the now horizontally polarised vertical whip aerial that's fallen down in the winds. That one is a bit bigger at about 5m in length and still has the guy lines attached. The pole broke before the chimney which is probably the prefered failure mode.

A falling aerial does a lot less damage than a falling chimney most of the time. You don't want a pole that will pull the chimney down before breaking which nobody appears to have told the OP.

[dave]

Because a 15 M pole needs a lot more to secure it to a building than a vertical antenna. I know, as I have had a shorter one bolted to my back wall and it can get quite vocal in high winds.

Work out the wind loading a 2 M aerial and again for a 15 M pole and come back with the results.

I would prefure to repair a window rather

The chimney can be claimed on the house insurance, a 15 M pole could not.

Dave

[geoff]

In message , "dennis@home" writes

That's not something which happens on a regular basis

other than the fact that we probably agree that you are a total eejit

[dave]

Please let us/me know how you go on. Many years ago, it was a white stick operator that taught me about microprocessors when IBM first thought about the format of a desk top.

He used to wire his computers around Motorola chips at that time using wire wrap techniques.

One of the best things he taught me, was never take a step forward, that I couldn't take back.

Dave