[BC] FM bays

[Broadcast List USER]

The fist thing I am going to tell you is what Bob is writing you is  
100% correct.

But it isn't the entire story.

Why?

Because he, like the rest of us, don't know "THE REST OF THE STORY."

YOU CANNOT MAKE A $200,000 INSTALLATION CHOICE BY SENDING AN E-MAIL  
TO A BROADCAST MAILING LIST -- FOR GOD'S SAKE!

There are so many things to think about!

Coverage in Kansas is different than Washington, DC, and that is  
different than Seattle, which is different than Denver.

What works in one market is NOT what works in another.  Even in the  
same market, things can change.

In GENERAL, 1/2 wave antennas are great, but if you need additional  
gain 1/n antennas can be pretty fine.  In THAT case, an even number  
of bays is sort of important (well, maybe not really) until the  
number of bays gets high.  Then it doesn't matter.

Still, THREE half-wave spaced bays work REALLY well, if that gain  
gets you the ERP you need.

You really need to consult a good consulting engineer or two, or  
three, not a bunch of guys on an e-mail list.  I read what has been  
published here and I just get sick.

PAY for some real advice!

Then again, Bob Groome has given some advice here, and I think it has  
been 100% correct.  Go ahead and contact Bob Surette at Shivley for  
some more correct advice.  They are both honest guys.

I don't know why you would ask for specific ENGINEERING advice on  
this list

--chip fetrow

On Feb 11, 2009, at 9:30 PM, broadcast-request at radiolists.net wrote:

> Message: 14
> From: Bob Groome <bobgroome at yahoo.com>
>
> As you are doing a slight reach pattern, the 6 bays would be  
> better. If you are going in a single direction for your target, a  
> face mount might be better than a leg or pole mount. If you want to  
> see some typical patterns go to:
>
> http://www.eriantennas.com/AntennaCalculator/FMCalca.htm
>
> And on the left hand part of the screen, choose horizontal  
> patterns; look for something near your frequency and tower size.  
> Those in the right side of the list are GIF (image) and on the left  
> are FIG (tabulations and pattern) The FIG requires the free viewer  
> program also on this same page. You can extract the tabulations for  
> use with any of the Longly-Rice programs to really let you get a  
> better estimate of what to expect in the real world.
>
> On the other hand, if you are wanting as omni as possible, consider  
> mounting on a Lambda™ tuned tower section. See:
>
> http://www.eriinc.com/pubs/080402009-W.pdf
>
> Gives a quick over-view of the nifty advantages of making the tower  
> look invisible as far as the H-Poll azimuth pattern is concerned.  
> And you could opt for full scale pattern optimzation so you will  
> know exactly what direction the signal will go and correct for any  
> V-Poll attenuation on the back of the tower/pole.
>
> Hope this helps in your panning,
>
> Bob Groome
>
> In any moment of decision, the best thing you can do is the right  
> thing, the next best thing is the wrong thing and the worst thing  
> you do is nothing .... Theodore Roosevelt
>
> Personal Web Site is: http://web.mac.com/bobgroome/index.htm
>
> Work E-mail is: bgroome at eriinc.com
>
> --- On Wed, 2/11/09, Mglin at aol.com <Mglin at aol.com> wrote:
>
>> From: Mglin at aol.com <Mglin at aol.com>
>> Well some of you know the best answer
>> for this.  Your help is  appreciated.
>>
>> Here is the question.  I am upgrading my FM
>> C3  25 KW  ERP  245'AGL, moving
>> to 328' AGL
>> Currently using OMB 6 bay with 9.5 KW TPO.  Bays are
>> .75 spaced