477 MHz antenna?

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FTX03
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477 MHz antenna?

Post by FTX03 » Tue May 22, 2012 8:57 am

Will my 477mhz stainless steel whip antenna (not elevated feed) be able receive freqs from 403 though 470 with out damaging the radio? I'm only transmitting on 477mhz ATM. Would a wide band antenna do a better job on these freqs and should I start using an elevated feed set up. I am use a Tait TM8200.


Cheers Dom.

Comint
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Re: 477 MHz antenna?

Post by Comint » Tue May 22, 2012 9:26 am

FTX03 wrote:Will my 477mhz stainless steel whip antenna (not elevated feed) be able receive freqs from 403 though 470 with out damaging the radio? I'm only transmitting on 477mhz ATM.
If you are only using it for receiving, it won't damage the radio, but it won't perform as well as an antenna intended for the specific frequency range.

Would a wide band antenna do a better job on these freqs and should I start using an elevated feed set up. I am use a Tait TM8200.
An antenna intended for the required frequency range will always do a better job, and height also helps.

--
Comint

FTX03
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Re: 477 MHz antenna?

Post by FTX03 » Tue May 22, 2012 10:06 am

Thanks. Do the elevated feed sections have freq ranges or is it Based on the antenna that's screwed to it?

FastR1Red
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Re: 477 MHz antenna?

Post by FastR1Red » Wed May 23, 2012 8:39 am

FTX03 wrote:Thanks. Do the elevated feed sections have freq ranges or is it Based on the antenna that's screwed to it?
Yes they do. The RFI and Polar antennas come with the GI frequency you specify. They have different coloured bands at the base.
It's for a couple of reasons, the cable length going into the base has to be precisely cut, (outer braid and inner conductor length, to go into the top of the GI section to couple correctly. The internal capacitance is different for each band, they run normally around 20MHz wide. Have seen a 490MHz antenna work ok on a 450 GI but it's not recommended.
HTH.

FTX03
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Re: 477 MHz antenna?

Post by FTX03 » Wed May 23, 2012 10:10 am

I see. What's the benifit of using an elevated feed opposed to a regular stainless whip on and base? (my current set up.)

Newy1234
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Re: 477 MHz antenna?

Post by Newy1234 » Wed May 23, 2012 2:47 pm

Dom, as Commit said if you are only receiving it will not damage the radio only transmiting at the lower freq's may damage it.

If you are worried about damage while transmitting just by a SWR metre and check the SWR for that antenna on all frequency's.

Comint
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Re: 477 MHz antenna?

Post by Comint » Wed May 23, 2012 3:29 pm

FTX03 wrote:I see. What's the benifit of using an elevated feed opposed to a regular stainless whip on and base? (my current set up.)
The elevated feed was originally developed for use with Police UHF antennas to get the antenna clear of the rotating reflectors of the Red and Blue lights, as they caused havoc to the radiated signal..

If you have no obstructions around your existing antenna, it won't make any difference.

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Comint

FTX03
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Re: 477 MHz antenna?

Post by FTX03 » Wed May 23, 2012 4:45 pm

Thank you mate.

melbourneradio
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477 MHz antenna?

Post by melbourneradio » Thu May 24, 2012 12:19 pm

As already stated if Rx only you will be right I use a rfi elevated feed for extended Rx on my uniden UHF have done for years no issues


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