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ANTENNA for UHF and CB Radio PLEASE HELP IM LOST.

Posted: Sun Sep 30, 2007 10:25 am
by Allaboutfourbys
HI GUYS,

I WAS DECIDING WHAT TO BUY YESTERDAY WHEN I WAS AT MY LOCAL 4X4 SHOP AND I HAD A LARGE RANGE,

I DECIDED TO BY A UHF AND CB (AM & FM) COMBINED THE TYPE I GOT WAS A UNIDEN (uh095sx)

My reasons for this is i am working on a mine site in out back queensland.
i need to be in contact with trucks and cattle stations and a lot of them still use AM to by pass the crap some D/Heads speek on the UHFs so now i am lost to know what antenna i need.

WHAT I WANT FROM AN ANTENNA IS GOOD RANGE AND CLEAR TRANSMISSION FOR BOTH AM AND FM

(BARE IN MIND I AM IN RUGGED COUNTRY AND I HAVE LOOKED AT A FEW I FOUND A DUPLEX WHICH WAS UHF AND CB COMBINED HOWEVER IS WAS NOT VERY BIG),

IS BIGGER BETTER??????

PRICE IS NOT AN ISSUE CAN SOME ONE GIVE ME THE HEADS UP ON WHAT I SHOULD GET.

I DONT WANNA MUCK AROUND, SHOULD I FIND A DUPLEX (uhf an cb in one antenna OR SHOULD I HAVE SEPERATE ANTENNAS FOR BOTH UHF AND CB ???????


ANY HELP WOULD BE GREAT

IM JASON - 0406,554,750 I WILL BE GREAT FULL FOR ANY ADVICE AND HELP.

Posted: Sun Sep 30, 2007 11:23 am
by marin
You will get better results from 2 separate antenna, positioned away from each other, so as not to interfere with each other. Combined antenna will generally be a compromise of performance on both frequencies ranges.

I would go with 2 good quality antenna, GME, Polar, etc.

marin

Posted: Sun Sep 30, 2007 12:16 pm
by zagan
Look around at the radio shop sites etc.

This may help you:
For UHF
You get 4db 6db and 9db

The 4db has the lowest range but goes out more in a larger circle so say it's a 3klm circle but it's above and below the 4wd.

This is great for radioing around hills

The 6db will go further but it's more of an oval type shape ok around some hills but is the mid range so bit of the best from both worlds but not super at 1 thing.

The 9db is for super long range 8 to 15klm etc, but it's a narrow signal so not really good for hills but on an open plain would be the best.

That should help, you can get a mix of DB antenna.

AM no idea I suppose it's sorta the same deal.

I suppose the best thing would be to ring up one of the radio shops and ask them.

Posted: Sun Sep 30, 2007 12:37 pm
by Harb
Seperate antenna's...........

The main problem is the HF CB section 27Mhz requires a "Ground Plane" to work.
Now a UHF does as well, but because of thge much higher Freq its ground plane is much smaller and you can put the antenna almost anywhere.

With the CB though the groundplane is absolutely the one most important thing to good operation.
Idealy the antenna for the 27Mhz section of the radio would be mounted in the middle of your roof, but this is sometimes hard, so mount it to the side on a gutter mount or boot lip mount etc etc .....it needs a large steel surface around its base.......larger the better.
The Transmission will be at its best in the direction over the largest area of metal.....ie if you mount it on the passager side roof, it will work best comunicating with people on you drivers side....etc.
For absoulute best results the antenna must be "tuned" to its new position with a VSWR meter.........That will realy get it singing.
Antennas are sold today "Pre Tuned"........this is just an average tune assuming you mount the antenna with a good groundplane in a good spot.
If the SWR is to far out, damage to the output transistors in the radio will occur.

cheers
Harb

Posted: Sun Sep 30, 2007 4:13 pm
by Jeeps
for the best possible range for AM you will want a 9ft stainless steel. They're hard to come by but work the best. Otherwise you can get what i've got, a "Monster Stick" or similar, about 7-8ft very thick fibreglass rod with an adjustable steel tip. It gets awesome range.

For UHF, don't touch anything but RFI if you want range. A standard 6.5db elevated feed RFI can beat most Benelec, GME or Mobile one antennas. Try to get a 6.5db antenna without a spring as springs reduce signal quality. And DON'T cut the cable if you get an RFI.

Testing with a GPS, my mate and i managed about 25klm in a straight line on the beach up at fraser a year ago with icoms and RFI antennas. My GME or Benelec couldn't match that distance.

cheers

Posted: Sun Sep 30, 2007 11:48 pm
by Allaboutfourbys
Jeeps wrote:for the best possible range for AM you will want a 9ft stainless steel. They're hard to come by but work the best. Otherwise you can get what i've got, a "Monster Stick" or similar, about 7-8ft very thick fibreglass rod with an adjustable steel tip. It gets awesome range.

For UHF, don't touch anything but RFI if you want range. A standard 6.5db elevated feed RFI can beat most Benelec, GME or Mobile one antennas. Try to get a 6.5db antenna without a spring as springs reduce signal quality. And DON'T cut the cable if you get an RFI.

Testing with a GPS, my mate and i managed about 25klm in a straight line on the beach up at fraser a year ago with icoms and RFI antennas. My GME or Benelec couldn't match that distance.

cheers
were do i get a RFI is that the type of antenna or is it a brand?

Posted: Sun Sep 30, 2007 11:55 pm
by +dj_hansen+

Posted: Mon Oct 01, 2007 1:01 am
by Jeeps
Allaboutfourbys wrote:
Jeeps wrote:for the best possible range for AM you will want a 9ft stainless steel. They're hard to come by but work the best. Otherwise you can get what i've got, a "Monster Stick" or similar, about 7-8ft very thick fibreglass rod with an adjustable steel tip. It gets awesome range.

For UHF, don't touch anything but RFI if you want range. A standard 6.5db elevated feed RFI can beat most Benelec, GME or Mobile one antennas. Try to get a 6.5db antenna without a spring as springs reduce signal quality. And DON'T cut the cable if you get an RFI.

Testing with a GPS, my mate and i managed about 25klm in a straight line on the beach up at fraser a year ago with icoms and RFI antennas. My GME or Benelec couldn't match that distance.

cheers
were do i get a RFI is that the type of antenna or is it a brand?
Dick Smiths sells RFI's i think the product code is D4027 or similar, it's about $80.