outdoor antenna for PMR446

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WARLOCK
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outdoor antenna for PMR446

Post by WARLOCK » 15 Jul 2015, 11:18

Need a good antenna to mount out doors any thoughts on this.
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Re: outdoor antenna for PMR446

Post by kr0ne » 15 Jul 2015, 18:04

2m/70cm collinear should do nicely... The obligatory "white stick".

Or anything for 70cm will work well and are relatively easy to source.

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Re: outdoor antenna for PMR446

Post by BK » 17 Jul 2015, 14:57

Yup, 446 is actually within the 70cm amateur band in some countries (e.g. the US) so any 70cm white stick antenna should work well.

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Re: outdoor antenna for PMR446

Post by Excalibur » 17 Jul 2015, 15:41

I was under the impression that the SWR for 70cm antennas wouldn't be very good for 446. Because I thought 70cm is at 433 Mhz while pmr446 is at 446 Mhz. So unless its an antenna that is designed for the US market like BK said it wouldn't have good SWR on 446?

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Re: outdoor antenna for PMR446

Post by BK » 17 Jul 2015, 16:44

Actually, taking the Diamond X50 as an example, you're right - the X50 is 430-440 MHz, you'd need the X50A which is 435-450 MHz.

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Re: outdoor antenna for PMR446

Post by kr0ne » 17 Jul 2015, 17:43

Seriously, it will be fine... ;)

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RogerD
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Re: outdoor antenna for PMR446

Post by RogerD » 17 Jul 2015, 19:52

446 is only 2.5% more than 435, it's not going to be an issue!

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Re: outdoor antenna for PMR446

Post by radiosification » 17 Jul 2015, 20:58

RogerD wrote:446 is only 2.5% more than 435, it's not going to be an issue!
I don't think SWR works like that!
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Re: outdoor antenna for PMR446

Post by BK » 17 Jul 2015, 21:03

Looking at the SWR curves for the Diamond X50 (page 3 of the linked pdf), the X50A has a great SWR at 446. The X50 curve only goes up to 440, but extrapolating it looks like it might be in the region of 2.5 at 446, which is good enough but not ideal.

http://www.radiomanual.info/schemi/ACC_ ... 0_user.pdf

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Re: outdoor antenna for PMR446

Post by kr0ne » 17 Jul 2015, 22:58

SWR, Schmesch W R... :)

I have a cheapo X50 style and I think it's around the 2:1 mark on 446... although it's been a while since I measured it...

There are antennas available that are tuned for 446, or there is home brew/mods if you are really anal about it, but 70cm stuff is readily and cheaply available and (in my experience at least) works very well...

People get all hung up on SWR, but actually it's not that important really. Personally, I'm more interested in the radiation pattern than the mythical 1:1 SWR. ;)

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Re: outdoor antenna for PMR446

Post by Mitch » 18 Jul 2015, 17:59

If you're only going to use it on 446 then any white stick will adjust to that, or you can make your own band specific colinear from coax: here and here, or look for more.

Or 6¼" w/ ground planes or 6¼" each way for a dipole. Not hard to do whichever you decide on.
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Re: outdoor antenna for PMR446

Post by Admiral » 18 Jul 2015, 18:09

If you're planning on using legal power on your illegal twig then you'll need some tasty coax, otherwise there won't be a lot of your 0.5w coming out of the top.
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Re: outdoor antenna for PMR446

Post by StormShadow » 20 Jul 2015, 02:37

I've tested 446 on an X30 and the SWR was fine

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Re: outdoor antenna for PMR446

Post by BK » 20 Jul 2015, 08:50

kr0ne wrote:People get all hung up on SWR, but actually it's not that important really. Personally, I'm more interested in the radiation pattern than the mythical 1:1 SWR. ;)
Yes, I wouldn't encourage anyone to chase a 1:1 SWR unless they get some kind of satisfaction from it, but it's worth trying to keep the SWR below 3:1 to prolong the life of your RF power amplifier final stage, especially if you've modified your radio to produce more power than it was designed for.
Radiation pattern will be fine with a short white stick, it's the really long collinears with a very narrow vertical beamwidth that you have to watch out for.

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Re: outdoor antenna for PMR446

Post by SE Scanner » 20 Jul 2015, 12:26

Haven't tried one, but I think the Sirio CX440 is the way to go for 446.

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