UHF Wiring

Either pick a permanant 12 v feed for the ability to leave it on when you have the ignition off (eg waiting to hear from someone meeting you at a camp spot etc).

Or just use your cigarette lighter circuit (or a mobile phone circuit in later vehicles)

Most have an in line fuse of about 3-5 amps.

Peak current draw depends on age and efficiency of the UHF. The new GME Tx3200/3400 pull about 1.6 Amps on Tx and bugger all on standby. An older unit may pull up to 2.5 amps on Tx.

If you want a temporary install just put a cig plug on the lead and plug it in when you use it.

Dave

Will,
Geo is right the power draw is small less than 4 amps so connecting into the Cigar lighter circuit is the go as the radio can be left on with the ign on assessories. Then when you turn everything off the radio is off as well.
I have mine wired this way and it is never turned off at the set.
Have done this in the last 4 vehicles.

Go straight to battery.

Just checked the current draw on my Icom IC400PRO and on Tx it is 4.0 Amps while on Rx it is 1.2 Amps at max volume. When on standby it _Affordable_Storage_Drawers.aspx 300 Milliamps (0.3 Amps).

Hope this helps you

Muddy

Always wire radio's direct to the battery. It eliminates, as mentioned above, interference, potential for shorting out, and other issues. If you wire it through some other circuit, in effect you are working through 2 fuses.
The radio's may not draw much when receiving, but when transmitting the drop in voltage through other circuits can often be enough to affect your transmission signal and strength.

Finally, probably the most important reason for connecting radio's direct to the battery is the stability of the voltage, Circuit boards do not like fluctuations in the powere supply and when connecting through other circuits, every time you turn something on or off or start the engine etc. you will find the voltage varies significantly.

Cheers,
Brett

Straight to the aux batt + and - [with inline fuse to +]

Straight to the battery and fuse both + and - wires.

If you wire it directly to the battery put your fuse as close as is practical (without being ridiculous about it) to the battery to prevent a short before the fuse smoking the wiring.

There's little point in fusing the -ve wire.

At 1.6 A draw it's unlikely that you will get enough voltage drop across a fuse to cause a problem but the contact quality between the crimped button (on glass fuses) or the female spade terminal on blade fuses can be a source of resistance.

You'd have to have a resistance of 0.5 ohm to 0.8 ohm to cause a 1 volt drop at the unit. With the engine running and an input tolerance typically between 11 - 15 volts being an absolute minimum on most units you would not cause any serious drop in radiated power. Even without the engine running and the battery sitting around 12.5 volts you'd struggle to notice it if at all.

More emitted RF is lost on these radios through less than optimal SWR now that nearly no-one tunes antennae after installation.

Dave

Dave