How much power for 2m/70cm mobile?

[KG5YWM]

Hey guys, I have a newbie question for you. I'm looking to buy a mobile 2m/70cm for the truck. Since we are talking about line of sight or repeater communications, how much power is really necessary?

Thanks!

 

[nd5y]

There is no way to answer that. It depends on your location, terrain, the path loss between you and the repeater or other station and the quality of the receiver in the other station.

 

[KG5YWM]

There is no way to answer that. It depends on your location, terrain, the path loss between you and the repeater or other station and the quality of the receiver in the other station.

Thanks. The area that I'm in is very flat, not very many tall buildings, but a lot of trees. The farthest repeater I'm hoping to hit is about 15 miles max. As far as the quality of the receiver, that remains to be seen. I haven't bought it yet.

 

[KK4JUG]

Most mobile units have multiple power capabilities, i.e. 10W, 25W, 50W, and you can change it on the fly if you need to. Fifteen miles in one area may be nothing. In another area, it could be a lot, depending on what's between you and the repeater. Go for the multiple power-type radio and only use what you need.

 

[ko6jw_2]

FCC rules and good operating practice require that you use the lowest power necessary to make a contact. I use low to medium power on my radios. Sometimes as low as 5 watts mobile and 2.5 watts handheld. As stated above terrain and path losses are critical. If you're in a bad location, cranking up the power may not help. A bad signal area is a bad signal area. In a marginal area high power will help.

 

[KC3ECJ]

Hey guys, I have a newbie question for you. I'm looking to buy a mobile 2m/70cm for the truck. Since we are talking about line of sight or repeater communications, how much power is really necessary?

Thanks!

If you are going with a trunk or hood mounted antenna be careful about RF exposure.

You don't want to go beyond 15 watts for UHF. You might be able to get away with 25 for VHF.

 

[nd5y]

TAs far as the quality of the receiver, that remains to be seen. I haven't bought it yet.

I meant the receiver on the other end.
The performance and quality or your receiver has nothing to do with how well other stations will hear you.

 

[KG5YWM]

I meant the receiver on the other end.
The performance and quality or your receiver has nothing to do with how well other stations will hear you.

After I posted, I saw what you were getting at. Sometimes I wonder about my own reading comprehension.
Thanks everyone!

 

[majoco]

...and when you do get your multi-power unit, get into the habit of switching to low power first and try that - if you don't hit the repeater, go up a notch and try again. Better for the rig, the battery and you too!

My little rig at home puts out 5watts and hits all the local repeaters, some are twenty miles away but they have the advantage of altitude.

 

[I_am_Alpha1]

If you are going with a trunk or hood mounted antenna be careful about RF exposure. You don't want to go beyond 15 watts for UHF. You might be able to get away with 25 for VHF.

Sorry, but my calculations don't match. As my teacher always said, "show your work." I have a hood mount antenna and I'm in compliance. 145/446 mhz, 1.5m from ant, 0/2.15 gain uptilt ant, 50w (over actual average), controlled environ. Of course my calculator could be broke.