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477 MHz antenna?

Posted: Tue May 22, 2012 8:57 am
by FTX03
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.

Re: 477 MHz antenna?

Posted: Tue May 22, 2012 9:26 am
by Comint
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.

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Comint

Re: 477 MHz antenna?

Posted: Tue May 22, 2012 10:06 am
by FTX03
Thanks. Do the elevated feed sections have freq ranges or is it Based on the antenna that's screwed to it?

Re: 477 MHz antenna?

Posted: Wed May 23, 2012 8:39 am
by FastR1Red
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.

Re: 477 MHz antenna?

Posted: Wed May 23, 2012 10:10 am
by FTX03
I see. What's the benifit of using an elevated feed opposed to a regular stainless whip on and base? (my current set up.)

Re: 477 MHz antenna?

Posted: Wed May 23, 2012 2:47 pm
by Newy1234
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.

Re: 477 MHz antenna?

Posted: Wed May 23, 2012 3:29 pm
by Comint
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

Re: 477 MHz antenna?

Posted: Wed May 23, 2012 4:45 pm
by FTX03
Thank you mate.

477 MHz antenna?

Posted: Thu May 24, 2012 12:19 pm
by melbourneradio
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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