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Re: [LPFM] Re: Purchasing dipole antenna for LPFM   Message List  
Reply | Forward Message #5073 of 6125 |
Personally I prefer RFI or RFS  in stainless steel   but a bit of an overkill
for LPFM   !!  only needed in sites where high possibility of intermod exits  and  alloy corrosion is very high !!
 
Steve
 
----- Original Message -----
Sent: Tuesday, February 13, 2007 11:47 AM
Subject: [LPFM] Re: Purchasing dipole antenna for LPFM

Hi-Tec (Christchurch) antennas are the way to go, I install them in
commercial environments, repeater sites etc.
Spend the extra money and get a commercial series antenna with fitted
balun and a tail of around 30 metres of RG-8.
Length of coax is irrelevant unless you are talking runs of 100 metres
plus.

The two most important things in your system are the transmitter and
the antenna, everything else is secondary, so these are where the
money should be spent.
Nothing will let you down more however than a cheap antenna system.

With a commercial antenna you will not have to be spending time
adjusting it, maintaining it etc.

--- In LPFM_Radio@yahoogroups.com.au, "Steve Jepson"
<steve.jepson@...> wrote:
>
> Where are you located Callum ?
> then I can give you a few ideas
>
> Steve
>
> ----- Original Message -----
> From: Callum Thomas
> To: LPFM_Radio@yahoogroups.com.au
> Sent: Saturday, February 10, 2007 5:46 PM
> Subject: [LPFM] Purchasing dipole antenna for LPFM
>
>
> I'm in the market for a dipole antenna suitible for an LPFM station.
>
> I've had a few quotes - which all seem to be around the same
dollar mark - however I'm not sure how to choose. Are there particular
things that I should be asking about and comparing - materials,
technical specifications etc.
>
> It would be great to hear from anyone who's been down this path
before and could pass on a few quick words of wisdom.
>
> Thanks
> Callum
>



Tue Feb 13, 2007 1:41 am

kiwihamsteve
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Message #5073 of 6125 |
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Personally I prefer RFI or RFS in stainless steel but a bit of an overkill for LPFM !! only needed in sites where high possibility of intermod exits and...
Steve Jepson
kiwihamsteve
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Feb 13, 2007
1:48 am

you can up your TX power to overcome Coax loss rem its the EIRP from Antenna that counts in the GURL !! so unless you have a very low power TX I don't think...
Steve Jepson
kiwihamsteve
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Feb 14, 2007
8:30 am

Quite true Steve, but I was curious to know why Peter made his original comment. ... metres ... it now....
wireless.radio
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Feb 14, 2007
11:46 am

You are right. I should have been more clear. If one uses a low power TX like the ones that are designed for that environment the shorter the coax, the better....
Peter Winter
matrix1075fm
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Feb 16, 2007
9:28 am

I made an original comment about coax length which was in relation to SWR,ie antenna matching and how good it was. The impedance of the antenna is repeated...
Keith
wantok.geo
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Feb 14, 2007
6:55 pm

Its better to have the antenna resonant / matched rather than to fiddle with cable lengths . Cable lengths critical on TV TX arrays where you have multiple...
Steve Jepson
kiwihamsteve
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Feb 14, 2007
7:36 pm

I think you miss the point a bit Steve. Of course the antenna has to be resonant but if you measure the SWR at the transmitter end of a non resonant cable, you...
Keith
wantok.geo
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Feb 15, 2007
4:32 am

Yes , If you have 300mW into a Half wave dipole in freespace you are close to the GURL max eirp I measure with a Bird43 meter But remember the GURL may...
Steve Jepson
kiwihamsteve
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Feb 16, 2007
9:41 am

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