Is 50 watts a waste?

[SvenMarbles]

I’ve spent a fair bit of time modeling my own location with software, and also doing a lot of empirical testing out and about. Home to car, car to car,.. Changing variables, Height, antenna gain, and power.
 

GMRS is UHF,.. The properties of UHF are the following,.. Lossy as heck on coax, is line of sight, can punch through manmade structures better than VHF can, but ultimately crashes into terrain and dies.. Doesn’t matter if it’s 5 watts or 500. Nothing defeats the mound of dirt. You really have only one remedy. Height….. On both the transmitting and receiving side. 
 

Power just really hasn’t ever been a substantial factor as far as variables go in anything I test or model from 15 watts to 50. Even 5 watts gets into the same places, just at a lower volume. But on UHF, the things that kill it seem to come into play well before the wattage difference between 15 watts and 50 does. 
 

Is running your GMRS at 50 watts just a waste of electricity? 
 

Tell me about why you might want to run a 50 watt radio over a 20 watt radio and not have to have such an amp draw…

[back4more70]

The first thing that comes to my mind is that you can always dial the power down on a 50-watt radio, but once you hit the max on the 20-watt there is nowhere left to go.

[WRQC527]

44 minutes ago, WSAK691 said:

Is running your GMRS at 50 watts just a waste of electricity? 
 

It depends. In the parallel universe of amateur radio. the axiom is to use only enough power to make the contact. The same should hold true for GMRS. If you're operating at 50 watts when you could do it on 5 watts, then yes, you are not only wasting power, but you are also putting excessive RF energy into the ether where it does no one any good. But if you're on your side in a Jeep with your antenna pointing toward the dirt and the closest help is 30 miles away and only reachable with 50 watts, then by all means crank it up. Like the axiom says, use (just) enough power to make the contact. Also, running any radio at its full rated power generates more heat, which ain't good for electronics. And some car electrical systems can't keep up with 50 watts anyway. I had a mobile Icom VHF/HF radio that would shut off if I transmitted on 50 watts. So there is that. But like a wise man said a minute ago, you can cut the power if you have it but you can't increase it if you don't have it. I think that's what he said.

[SvenMarbles]

9 minutes ago, back4more70 said:

The first thing that comes to my mind is that you can always dial the power down on a 50-watt radio, but once you hit the max on the 20-watt there is nowhere left to go.

That’s definitely true..

But here’s another enecdote. I once received an SSTV image from a cube-sat that transmitted at 1 watt.

The point being that if you’re in the clear,.. You’re in the clear.. 1 watt or a factor of 10 doesn’t matter..

[OffRoaderX]

50W is good, especially when you have a long-run of that leaky coax, to get more juice squirting from the antenna.

50W is also good to step on the other guy that is irritating everyone but only has 20W.. all else being equal.

[SvenMarbles]

37 minutes ago, OffRoaderX said:

50W is good, especially when you have a long-run of that leaky coax, to get more juice squirting from the antenna.

50W is also good to step on the other guy that is irritating everyone but only has 20W.. all else being equal.

Yes. That’s something I hadn’t considered. I could step on top of the strange random men who are also on channel if I wanted lol. 
 

In my use case though, it’s just the wife son and whoever else I decide is a relative that day for GMRSing. 

[WSAW350]

1 hour ago, OffRoaderX said:

50W is good, especially when you have a long-run of that leaky coax, to get more juice squirting from the antenna.

50W is also good to step on the other guy that is irritating everyone but only has 20W.. all else being equal.

 

[WRXP381]

In my opinion is the coax and antenna are waay more important than wattage. Line of sight and height is always a big factor.    My 20w base unit does 234 miles into the Las Vegas repeater from my location in the Southern California desert and it comes in with great reports from net control in Las Vegas.  Would 50watts matter?  Might come in even better but no one has ever told me I need more.  And no one is annoyed either.  

[SvenMarbles]

27 minutes ago, WRXP381 said:

In my opinion is the coax and antenna are waay more important than wattage. Line of sight and height is always a big factor.    My 20w base unit does 234 miles into the Las Vegas repeater from my location in the Southern California desert and it comes in with great reports from net control in Las Vegas.  Would 50watts matter?  Might come in even better but no one has ever told me I need more.  And no one is annoyed either.  

That’s a good example. You’re probably at an optimal terrain position to be able to do that. You’re doing it with 20 watts.

lets suppose you were in a sub-optimal terrain position. The 50 watts wouldn’t fix it..

[WRKC935]

Well, it's gonna depend on the situation.  The terrain that you are communicating across, the gain of the antenna's at both ends, the height of the antenna's at both ends and lastly the power at both ends. 

First scenario.  Simplex communications between two vehicles since we are talking about using 50 watts.  Antenna heights are roughly the same, and no obstructions between you and the other vehicle.  Yes, there is a difference here, being the distance that stable communications can exist.  You are not limited by the other end being lower, or having less antenna gain.  So it will matter in this specific situation. 

Second scenario, Simplex to a portable (handheld radio).  In this instance the 50 watts is completely useless.  The other end of the conversation has neither the ability to match your power or antenna gain.  Height may be similar, but they are giving up 10dB of signal level (5 watt radio).  They are also giving up an additional 3 to 6 dB of gain or possibly more due to the portable radio having an antenna that has little to no gain.  You will loose the ability to hear them long before they can no longer hear you.  

Third scenario, repeater use, repeater with 200 foot or better antenna height, antenna has gain.  Here is where the power MIGHT have some advantage, but typically not.  For every time you double the height of an antenna you gain 6dB of perceived gain.  It your antenna is at 10 feet (a bit high for a mobile but easier to run numbers) you get to the point that curvature of the earth plays a bigger role in creating an obstruction than the path loss for the distance given.  On flat ground, the horizon due to curvature is 11 miles.  Meaning that LOS or Line Of Site exists at ground level for that distance. Once you are further than that away, the ground becomes the obstruction.  As you raise the antenna up, you regain LOS for a specific distance per 10 foot of height of antenna.  It's not really allowing you to 'see' over the horizon, it actually placing the antenna back into the LOS due to the increased height.  Remember with this, UHF signals travel in straight lines.  Lower frequencies behave differently.  But GMRS is 462/467 so we are staying with that.  The 'path loss' which is the amount of signal loss over a given distance between two antenna's in open air isn't going to be great enough to attenuate the signal of a 50 watt radio before the curvature blocks the signal.  This even applies with antenna's that are significantly higher than 200 feet.  Consider that ham operators operate portable radios with modest gain directional antenna's and communicate with satellites that are hundreds of miles away from them in space.  With 5 watt handheld radios.  SO again, path loss is NOT going to have any effect.  And 50 watts or 500 as you stated, will NOT defeat the ground blocking your signal.

 

[WRYZ926]

There is another thread that explains the loss of different types of coax cable. It is worth reading. And that is also why most of us will use LMR400 or equivalent coax for our base station antennas, it has the lowest loss per 100 feet for UHF.

Range is very dependent on location. This of us in the midwest and eastern parts of the country will probably never see 60 or more mile ranges due to terrain, forests, structures, noise floor, etc, etc. Those in the deserts with clear line of sight over gray distances and little to no noise floor will have greater range.

The quality of your coax and antenna, along with the antenna height above ground matters. I can get into the GMRS repeater that is 21.5 miles away on low power (5 watt) with my KG-1000G hooked to my Comet CA-712 antenna mounted above the roof (20 feet above ground). But at low power, my transmission volume is a bit low for others to hear.  I can probably use any of my HT's hooked to that antenna too. I also have a Wouxun KG-XS20G in my SxS with a Comet 2x4SR antenna that works great getting into the repeater.

25 miles is about the maximum distance I can talk to anyone on simplex with my 50 watt base station. The others that I can reach have their antennas either at 30 feet or 60 feet. But we have to use high power to hear/understand each other. Granted line of sight for the other guys from my location is just barely over the local terrain and forests.

[marcspaz]

First, there is a common understanding in the world that we should only use as much power as we need. So, how much do you need for your reliable communications? 

 

Second, there is a common misconception the you have to quadruple your power to make a usable difference. However, the reality is, on any given instant you never know how much or how little more power will really make the difference between getting your message out or not.

 

Last, in my opinion, you can never have too much love, money or power. 

[WRYZ926]

4 minutes ago, marcspaz said:

First, there is a common understanding in the world that we should only use as much power as we need. So, how much do you need for your reliable communications? 

This is very true. The local 2m,70cm, and GMRS repeaters are all on the same tower 21.5 miles away. I use mid power on my 50 watt base radios since I do not need to use high power. Now high power is needed at times when talking simplex on all three bands.

[TDM827]

My next radio will be 50 W for the reasons discussed here. I can use reduced power when it makes sense and I can use full power if needed. Unless it comes down to budget, 50 W makes a lot of sense.  

[WRYZ926]

It's definitely easier to turn the power level down than it is to add power when needed. I'll use low power on my base station or even a HT when talking to someone across town on simplex so I don't blow them out of their chair.

[Sab02r]

There is nothing wrong with running a 20watt unit.  My 20watt mobile units serve me just fine, especially when traveling in a caravan or as a loose-knit group.

My 50watt base unit may or may not expand the range at which I can reliably reach those mobile units, as there are impediments, limitations, and points of diminishing returns with all things physical and electrical. but it does have many features that make it handy to use as a base unit (such as scan groups) that my mobile units do not necessarily have...and if I am paying more for those extra features that extra wattage doesn't hurt my feelings any.

[bd348]

Use a handheld connected to a base antenna in the 2nd story window.  5W gets to the 20 mile repeater just fine.  Once I tried the low power setting, which is 1/2W.  It still got through but they said it was a bit scratchy.

[Lscott]

On 3/8/2024 at 11:00 PM, WRYZ926 said:

And that is also why most of us will use LMR400 or equivalent coax for our base station antennas, it has the lowest loss per 100 feet for UHF.

At a reasonable cost. There is better cable, various types of "hard line", but gets expensive real fast.

[WRYZ926]

43 minutes ago, Lscott said:

At a reasonable cost. There is better cable, various types of "hard line", but gets expensive real fast.

This is true.

[Lscott]

I think LMR600 has lower loses, a bit larger than LMR400, and I think it's not much more expensive either. The loss at 450MHz for LMR400 is 2.7db/100 feet. The loss at 450MHz for LMR600 is 1.7db/100 feet. For somebody who needs to run between 50 to 100 feed of coax stepping up to LMR600 would makes sense. The chart frequency of 450MHz is close enough to GMRS at 462/467 MHz the extra loss at the slightly higher frequency isn't that significant.

For 50 feet of LMR400 at 450 MHz the power loss would be about 27%.

For 50 feet of LMR600 at 450 MHz the power loss would be about 18%.

[nokones]

8 minutes ago, Lscott said:

I think LMR600 has lower loses, a bit larger than LMR400, and I think it's not much more expensive either. The loss at 450MHz for LMR400 is 2.7db/100 feet. The loss at 450MHz for LMR600 is 1.7db/100 feet. For somebody who needs to run between 50 to 100 feed of coax stepping up to LMR600 would makes sense. The chart frequency of 450MHz is close enough to GMRS at 462/467 MHz the extra loss at the slightly higher frequency isn't that significant.

For 50 feet of LMR400 at 450 MHz the power loss would be about 27%.

For 50 feet of LMR600 at 450 MHz the power loss would be about 18%.

It's just 1 dB, not significant and you won't know the difference in the operating  distance unless you buy your cable from Amazon. 

[marcspaz]

1 hour ago, Lscott said:

At a reasonable cost. There is better cable, various types of "hard line", but gets expensive real fast.

 

I got a new repeater a few days ago and started pricing hardline for the new setup... it's going to cost me about $1,300 for 250 feet and a couple of connectors.  I only paid $350 for the repeater.  It's wild... but if you want it to work...

[Lscott]

38 minutes ago, nokones said:

t's just 1 dB, not significant and you won't know the difference in the operating  distance unless you buy your cable from Amazon. 

For a db or two that's true for most people. With a modest gain antenna the coax loses can be compensated for. For people on the very fringe of a coverage zone every db counts.

[WRYZ926]

It is important to use the correct type and good quality coax. The cheap Amazon coax will have more loss than TM LMR400 or the Messi and Pailoni equivalent. The cheap coax won't have as much braided shielding and/or use lower quality materials which leads to more loss.

Using a good antenna with at least 6dBi of gain will overcome the 1-2 dB loss from the coax. Again use quality coax and quality connectors (if making your own cables).

[Lscott]

1 hour ago, WRYZ926 said:

Again use quality coax and quality connectors (if making your own cables).

I've tried installing my own connectors, wasn't easy, didn't turn out that well. Unless you've done a lot of it, and have the right tools, it's money well spent to just buy a cable with the connectors already installed. One less question mark if things don't work as planed.