Common UHF problems

[taslucas]

Thanks for that mate. Plenty if good info there. I will keep looking but Im in no real rush.

[threedogs]

You need a 5 watt unit with a good antenna , you can buy those base loaded [silver] antenna that you just change the tip to suit the terrain, Tips include short 4" job a to one about 450mm long or the spiral S/S wire tip. As TPC mentions the less joins in antenna cable the better, mount opposite other antenna ,as it can cause interference in some cases. Swr meters are cheap, but trouble is you only need it once. They were popular when CB or 27mhz radio was in vogue you snipped a little off the tip of wire until correct reading was reached. Your local UHF/communication shop should know whats best for Tassie, but I'm guessing it's not a tall antenna. Also look what others are running

[taslucas]

Hey John, thanks for the reply and I know your only trying to help but please read through the thread first. Most of what you said has been covered.

Its a brand new 80 channel Uniden unit. I brought it over a year ago but its only been turned on for about an hour.......

................ So far i think i need:

3db for the terrain im in (possibly with a 4.5 interchangeable whip).
Around 600-800mm tall to help help clear the roof line from the bullbar mount.
Stainless steel as opposed to fibreglass to help with tree strikes. (perhaps with one of those lock pins in the spring).
A ground plain independant.
Nice thick heavy duty/good quality coaxial cable.
And my fingers crossed that i havent wrecked my UHF unit!
Does that sound like im on the right track?

[Robo]

no negative effect and yes make sure all cables have good connections..

with the antenna cable, try and keep it one length with no extra connections as with each connection you get a slight loss in Db............. now where was that thread that ET responded to, which talked about all this

I remember reading the length of cable needs to be a certain length also.
result is better reception and or output.
sorry, this is something I know nothing about so cant elaborate further.

[NP99]

You know your antenna is too big when you park in underground car parks or drive through at KFC. Mine is powered to the ignition, didn't want to risk a flat battery, it's all personal choice on the power mode! Omni directional is probably fine for convoys mounted on the bulbar.

[taslucas]

It's more the trees and over grown tracks that will impact on aerial length for me. I do like KFC though...... Lol

[GQ TANK]

Some clarfiaction:-



1/4 wave length antenna is related to the freq being used. For optimum power transfer the antenna is cut to a length that it is equal to a 1/4 of the freq wave length. 1 wave length at 477 Mhz = 628,93 mm, therefore a 1/4 wave length is 157.2mm (628,93 mm / 4)

dBi is a measurement that compares the gain of an antenna with respect to an isotropic radiator (a theoretical antenna that disperses incoming energy evenly over the surface of an imaginary sphere.)

dBd compares the gain of an antenna to the gain of a reference dipole antenna = Roof mounted 1/4 wave antenna.

Db is a difference eg:- if I have a 3 dbd and a 6 dbd antenna, then there is a difference of 3db.

Some manufacture like to quote their antennas in dbi as for the unwary it looks better. A 3 dbd and a 5.1 dbi antenna have the same gain - what is more sellable.

Keep the cable runs as short as possible, and with out connectors.

Stainless / fibre glass antenna - I have seen some stainless whips fail due to road vibration - usually due to a lot of driving on ruts, I have seen fibre glass antenna destroyed by bird strikes.

If you park your truck for long term - the standby current draw from your radio can flatten the battery.

[GQ TANK]

This is ok"-

3db for the terrain im in (possibly with a 4.5 interchangeable whip).
Around 600-800mm tall to help help clear the roof line from the bullbar mount.
Stainless steel as opposed to fibreglass to help with tree strikes. (perhaps with one of those lock pins in the spring).
A ground plain independent.
Nice thick heavy duty/good quality coaxial cable. - Mobile Antenna cables normally come with fitted with rg58 - thin cable. Thicker cable = different connectors to suit

Only use Omni antennas for vehicles - directional antennas are used for base sites ( when you need extra coverage or reduced coverage in a particular area)

[taslucas]

Edit, sorry just saw your second post

Thanks

[Winnie]

Would RG6 quad shield coax used for TV installs be suitable for use?