UHF Wiring

Submitted: Tuesday, Mar 08, 2005 at 15:00
ThreadID: 21049 Views:8034 Replies:8 FollowUps:15
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Which circuit should I wire my UHF into? How much current do UHFs typically draw (peak).

Cheers
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Reply By: geocacher (djcache) - Tuesday, Mar 08, 2005 at 15:07

Tuesday, Mar 08, 2005 at 15:07
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
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Reply By: Member -Dodger - Tuesday, Mar 08, 2005 at 15:43

Tuesday, Mar 08, 2005 at 15:43
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.
I used to have a handle on life, but it broke.

Cheers Dodg.

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Follow Up By: Muddy 'doe (SA) - Tuesday, Mar 08, 2005 at 18:18

Tuesday, Mar 08, 2005 at 18:18
The radio I have is an Icom IC400Pro and I initially had it wired to the ignition which is the default way many installers do it.

After my first weekend trip I found this a right PITA. The radio would go off with the ignition but must be turned on again manually when power is restored (ignition on). I found that having to turn it on EVERY TIME I restarted the vehicle was just silly. I would stop in convoy for a cuppa and turn the car off - off goes the radio and I miss calls. If you forget to press the button when you take off again then someone may be calling you and you drive on blissfully unaware......

I had it rewired direct to battery and find it terrific. It goes on at start of trip and goes off at end of trip. No mucking around and when on standby it _Affordable_Storage_Drawers.aspx power measured in milliamps. Stuff all.

Cheers
Muddy
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Follow Up By: Tuco - Wednesday, Mar 09, 2005 at 11:00

Wednesday, Mar 09, 2005 at 11:00
Hey Muddy,

There are a couple of settings with the Ic 400 Pro that can be changed/enabled with the Icom software.

While I always wire my radios directly to the battery - the Icom software will let you 'enable' the IGSW feature. This will " When the ignition switch is turned ON, the transceiver power turned ON automatically." So then you wont have to turn it on.

Another annoying feature that can be disbled is the loud beep when the radio is turned on. The "IC400PRO" text that comes up on the display can be edited to whatever you want - however if it is left blank, then the radio will go directly to the last channel used WITHOUT THE BEEP when it is turned on.

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Follow Up By: Muddy 'doe (SA) - Wednesday, Mar 09, 2005 at 18:20

Wednesday, Mar 09, 2005 at 18:20
Thanks for that Tuco - that bloody beep is soooooo annoying! These settings can only be changed with the software?

Muddy
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Follow Up By: Tuco - Wednesday, Mar 09, 2005 at 22:03

Wednesday, Mar 09, 2005 at 22:03
G'gay Muddy - unfortunately yes - can only be changed with the cloning cable and software. All available user changeable settings can be accessed via the 'set mode' - page 28 in your manual.

Tuco
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Reply By: Brew69(SA) - Tuesday, Mar 08, 2005 at 17:07

Tuesday, Mar 08, 2005 at 17:07
Go straight to battery.
AnswerID: 101594

Follow Up By: Member - Roachie (SA) - Tuesday, Mar 08, 2005 at 18:09

Tuesday, Mar 08, 2005 at 18:09
I totally agree with Brew on this point. Less chance of interference from associated circuits etc. As stated, it will use buggar all power even if left on over night or for several nights in a stand-by capacity.

Cheers,

Roachie
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Reply By: Muddy 'doe (SA) - Tuesday, Mar 08, 2005 at 18:26

Tuesday, Mar 08, 2005 at 18:26
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
AnswerID: 101603

Follow Up By: Member - Banjo (SA) - Tuesday, Mar 08, 2005 at 20:32

Tuesday, Mar 08, 2005 at 20:32
I haven't used my Icom 400 seriously yet Mud but that 4 amps is grunty eh ? The old TX3000 came with a 1 amp fuse - upgraded to 2A at some stage when the first one blew. Seems that the 4A fuse would cover the optional commercial 25W mode in the Icom ? In CB mode, a bit less than .5A x 12 volts = the 5 watts in Banjomath.
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Follow Up By: Muddy 'doe (SA) - Tuesday, Mar 08, 2005 at 20:49

Tuesday, Mar 08, 2005 at 20:49
May need a bigger fuse Banjo.

When transmitting at 25W it _Affordable_Storage_Drawers.aspx 7 Amps according to spec!

Cheers
Muddy
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Follow Up By: Muddy 'doe (SA) - Tuesday, Mar 08, 2005 at 20:59

Tuesday, Mar 08, 2005 at 20:59
some good info here about the Icom
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Follow Up By: Tuco - Tuesday, Mar 08, 2005 at 21:07

Tuesday, Mar 08, 2005 at 21:07
My new IC 400 Pro came with a 10 Amp fuse.

Just spent the last few hours programing all the vacant channels.

Mine only came up with 3.5 W out of the box - have now tuned it up to 5 W. The 25 W setting was also down - at 19 W - have now fixed that too!
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Follow Up By: Mad Dog (Australia) - Wednesday, Mar 09, 2005 at 11:35

Wednesday, Mar 09, 2005 at 11:35
Four amps is a lot of juice for a measly 5 watts, doesn't sound quite right to me. the GME 4400 is only 1.4 amps. My Icom IC208 is 12 amps but that's 55 watts.
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Follow Up By: Bonz (Vic) - Wednesday, Mar 09, 2005 at 17:25

Wednesday, Mar 09, 2005 at 17:25
Muddy's isnt 5W Ray its 25 mate. its a easy software change to make it 25 instead of 5.
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Follow Up By: Mad Dog (Australia) - Wednesday, Mar 09, 2005 at 17:56

Wednesday, Mar 09, 2005 at 17:56
Take it easy Geoff, relax a bit when you get home from work. Read the thread again.
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Follow Up By: Bonz (Vic) - Wednesday, Mar 09, 2005 at 18:00

Wednesday, Mar 09, 2005 at 18:00
I thought you meant Muddy referribg to his 4 amps, yannow I am a lectrical injuneer..... and 80 new thread s to read after 2 days away is lots must be reading too fast
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Reply By: Big Woody - Tuesday, Mar 08, 2005 at 18:57

Tuesday, Mar 08, 2005 at 18:57
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
AnswerID: 101605

Reply By: TheUndertaker - Wednesday, Mar 09, 2005 at 11:26

Wednesday, Mar 09, 2005 at 11:26
Straight to the aux batt + and - [with inline fuse to +]
AnswerID: 101713

Reply By: Mad Dog (Australia) - Wednesday, Mar 09, 2005 at 22:14

Wednesday, Mar 09, 2005 at 22:14
Straight to the battery and fuse both + and - wires.
AnswerID: 101844

Reply By: geocacher (djcache) - Thursday, Mar 10, 2005 at 22:59

Thursday, Mar 10, 2005 at 22:59
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
AnswerID: 102010

Follow Up By: Mad Dog (Australia) - Thursday, Mar 10, 2005 at 23:19

Thursday, Mar 10, 2005 at 23:19
Dave, the -ve is fused to prevent the radio chassis and antenna earth being used as a return path in case the battery to block earth becomes open circuit. All my Ham rigs came with both the - and + wires fused from the factory.
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Follow Up By: geocacher (djcache) - Friday, Mar 11, 2005 at 00:17

Friday, Mar 11, 2005 at 00:17
Hi Ray,

I suppose that's a point but there'd be many other pieces of equipment that could do the same thing in a modern 4wd and we don't fuse the negative rail of any of them.

I don't think I'll bother.

Interestingly Codan don't fuse the negative rail of their gear that I've seen.

Must dig out the old theory books and have a read, you've got me curious.

Dave
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