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Author Topic: UHF or VHFhi/lo range question  (Read 3151 times)
8THMAN
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« on: November 06, 2006, 01:17:45 PM »

I am looking for reliable handheld communications for hunting trips in hilly terrain.  I get different answers as to what band would provide the most range.  I understand that in principle low-band VHF gets more distance, but suffers from an inefficient (standard) antenna.  UHF units come with a full 1/4 wave antenna but do not handle hills and trees well.  High-band VHF falls somewhere in the middle.  I do not wish to buy tri-band radios; what is my best bet for this kind of outdoor duty?

I realize that this question has been gone over many times before, but I have not been able to get a simple answer -- maybe the problem is just too complex.  Thanks for any help you might have.
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WB2WIK
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« Reply #1 on: November 06, 2006, 01:24:12 PM »

Actually, impossible to answer without having the specifics of the equipment in question.

Path loss is lower at lower frequencies, but antennas are less efficient and this relationship is what usually makes it a "wash" between VHF and UHF for line-of-sight coverage.

If you need to extend the range of hand held communications beyond that possible with typical FM transceivers and their attached whip antennas, you can try larger antennas, or using SSB equipment instead of FM (assuming you're a licensed amateur).  The FT-817ND, for example, runs 2.5W PEP SSB output power on 50, 144 and 432 MHz and when doing so has GREATLY extended range, compared with 2.5W FM output power on those same bands.  The difference can be night and day -- like several miles extra range between portable transceivers and their attached antennas.

WB2WIK/6
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KE4SKY
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« Reply #2 on: November 07, 2006, 11:33:23 AM »

Kyle,

If all your hunting and camping buddies are licensed hams, and you want relatively small and inexpensive  pocket radios for "walk and talk", while carrying packs and other gear, a 2 meter HT  with a full sized quarter-wave and dangling counterpoise makes sense.

If not everyone is licensed, then I'd go for VHF MURS with a similar antenna. SSB derives much of its benefit from all stations being horizontally polarized, having a lower noise floor and better antennas. All mode rigs are more expensive and not pocketable. MUCH  less practical for walking around, more for a stationary camp set up.
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WB2WIK
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« Reply #3 on: November 07, 2006, 11:41:12 AM »

>RE: UHF or VHFhi/lo range question       Reply
by KE4SKY on November 7, 2006    Mail this to a friend!
SSB derives much of its benefit from all stations being horizontally polarized, having a lower noise floor and better antennas. All mode rigs are more expensive and not pocketable. MUCH less practical for walking around, more for a stationary camp set up.<

::That part's not true.  SSB derives all of its benefit from being a weak signal mode that uses linear detection that can make a very weak signal 100% solid copy.  FM is a strong signal mode, and when a signal drops below about 12 dB quieting, it's impossible to copy at all...so right there, SSB has about a 12 dB communications advantage over narrowband FM, regardless of what antennas are used.

WB2WIK/6
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8THMAN
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« Reply #4 on: November 08, 2006, 08:52:29 AM »

Thanks for the helpful information!

Kyle
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M3GYO
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« Reply #5 on: December 03, 2006, 02:30:40 AM »


by KE4SKY on November 7,
SSB derives much of its benefit from all stations being horizontally polarized, having a lower noise floor and better antennas. All mode rigs are more expensive and not pocketable. MUCH less practical for walking around, more for a stationary camp set up.<


by WB2WIK November 7,
That part's not true. SSB derives all of its benefit from being a weak signal mode that uses linear detection that can make a very weak signal 100% solid copy. FM is a strong signal mode, and when a signal drops below about 12 dB quieting, it's impossible to copy at all...so right there, SSB has about a 12 dB communications advantage over narrowband FM, regardless of what antennas are used.<


Hmmm, For me, they are both right! in some respects, its just that they dont quite see it in the same way.
For me the difference between SSB and FM is that SSB has the lower noise floor, its as simple as that,
regardless of antenna used. However, MOST SSB users are Horizontally polorized (with better gained antennas), and MOST FM users are Vertical (co-linears), and Vertical FM users can ONLY enjoy distant contacts -DX- when there is a lift. period.

In my opinion, using SSB will (for the same power used as FM) in theory, Will get your signals further just because of the lower Signal to Noise ratio.

Why not listen to some of my weak SSB contacts swapping over to Horizontal FM and hear for yourself what difference it makes? or better still, why not try it yourself?

http://www.2e0gyo.co.uk/Radio_Amateur/hfm/index.htm

I would love to hear about your Horizontal FM results.

Regards
Alan
2E0GYO


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NA0AA
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« Reply #6 on: February 08, 2007, 04:20:39 PM »

When I was doing SAR work, we used VHF-Hi channels and I was constantly amazed by the range available with our HT's even in the Colorado Rockies - you really had to work to walk out of range - w/out repeaters - we worked simplex.

One option if you are remote is to use dual band radios and have a cross-band repeater set up?

I would think that 5 watts FM should be adequate for most use.

I would however, carry one of those collapsable whip antennas as an emergency range extender though - rubber duck antennas just are not that good.

A mobile with a decent antenna is a great range extender.
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