Mobile power?

[esmphoto]

Hi there!
I’m new here, and I have a question about a new mobile radio installation.
I just purchased a Kenwood TK-880 25watt UHF mobile radio and am about to go about installing it in the console of my Volvo SUV. The easiest way to power the radio would be to run the included power cable just a few feet to one of the many blank fuse slots in the accessory fuse panel underneath the driver side dash, but the Kenwood service manual says that both the positive and negative must run directly to the positive and negative terminals of the battery, which is located in the spare tire compartment all the way in the rear of the car.

I suppose I could run some heavy duty wire through the center channel from the battery to the console, But it would be so much easier to just use the fuse box.

If the Kenwood only draws 6 amps while keyed why does it have to run all the way to the battery? Why can’t I ground to the chassis? Engine/ignition noise?

[M0VKG]

I think the reason is for - as you say - engine and ignition noise. It also theoretically lessens the likelihood that RF will get into the car's electrical systems, although you're never going to completely remove that possibility!

The way you do it is really up to you. Many people have done what you're wanting to do, without any problems. YMMV...

[G4NVB]

I've just completed installing a FT-8900 in a Ford Focus, I ran the power directly from the Car Battery.

[Ham Man]

Well - the answer might be - because the radio demands a certain amount of power all the time in order for it to work properly and transmit time is only maybe 10% while standby is the other 90.

In standby mode the Yaesu FT 8900R only requires about 2 amps of power, but it really likes 13.5 volts.
As long as the charging system see's a discharge - it will keep trying to charge the battery and will keep the power up as long as the radio is turned on.

New vehicles such as the Chevrolet pick up trucks uses pulse width modulation to monitor the battery and will only charge the battery when it see's a discharge in the battery.
The ignition also uses pulse width modulation and the fuel pump also displays a lot of RF noise.

Your goal should be to get as far away from the noise as possible.
I have heard others in the past that had noise issues in their transmit signal - and were unwilling to work on their situation to make it better.
In the end, no one wanted to talk to them because all you could hear is the alternator whine in the background.

If you look at the wiring harness for most new vehicles, the power wires going into the fuse block is insufficient to support the power requirements for most mobile radios of any size and that is another reason why to run the power wires directly to the battery.

If a person is unwilling to do even the most basic work to install a radio, then technically they shouldn't be installing radios by themselves.
Technically what we do in amateur radio is broadcasting. even if it is just a .500 mw walkie talkie. We need to treat our signals with care so we sound and look professional to those around us. When you put out a crappy signal - it makes us all look bad.

Just from the people with the crappy signals, after a while it ends up sounding like the CB radio and when the bands gets too bad - people just ends up shutting the radio off or turning the channel when those individuals comes on the air.

Usually the people who sounds the worst on the amateur radio - 2 meters / 440 mhz is the new hams that doesn't want to do any work and doesn't want to spend any money on a good rig and doesn't want to put an antenna on their vehicle and doesn't want to purchase a antenna for their home QTH.

Most times when I hear someone say - I have a J Pole antenna and a walkie talkie - I end the conversation right there. Those people are not real hams and they are not the kind of people that I want to associate with.

[KM3F]

....One reason you should run the power leads to the battery is to have the lowest voltage drop.
....The car's wireing is not as heavey as your supplied leads.
....What can often happen when you try to use the radio with the engine off and radio connected to a fuse panel is a voltage drops so far that the radio can shut down when you try to key up.
....Also you must fuse the leads at the battery for safety. If the positive lead should short along it's length a fire could result and you lose your SUV if there is no fuse protection at the battery.
....If the radio picks up alternator whine, you can insert a filter in the power leads near the battery to eliminate it..
...If you hear other noises on receive, then work has to be done to find the source, then steps taken to reduce or eliminate that noise.
That's about it for FM mobile installation.
Good luck.

[AB3NK]

A 25 watt radio does not demand all that much power.

You could try and run it with a adapter that plugs directly into the lighter socket.

The bottom line is that most vehicles transmissions are run with a type of pulse width modulation as does the alternator and the fuel pump.
All this stuff generates a lot of RF noise which you are trying to get away from.

Properly bonding the antenna to the body will help with a 2 meters type radio also.
You want about 3 feet square under the antenna to establish a proper counterpoise.

I saved a link which might be of some help to you about this.
http://www.k0bg.com/

http://www.k3cc.net/id26.html

[5B4AJB]

lighter socket.

The decent ones are rated at 10A, crappy ones a lot less.

My 2m radio with 25W linear draws 10A.

If I run it from the cigarette lighter, the car's center console gets hot, so I put in some wiring to the battery and a flying socket. Job done.

[2E0JTP]

[snip...] Most times when I hear someone say - I have a J Pole antenna and a walkie talkie - I end the conversation right there. Those people are not real hams and they are not the kind of people that I want to associate with.

Seriously?

ROFL