In theory, doubling the power should increase your range by 41.4-percent (square root of 2) and 4-times the power should increase the range 100-percent. However, there are so many other factors involved that, in the real world, absolute range is often increased by 10-percent, or less. It has been my experience in the commercial two-way field that increasing power usually shows up as a less noisy signal where the signal was previously noisy.
Terrain features, where line of sight communications are concerned, have a much greater effect on the transmitted signal at any particular receiving point than anything else. Remember, the horizon for r.f. is right at 33-percent farther than visual line of sight. The result is that the r.f. follows Earth curvature for a distance 1/3rd farther than what one can see.
On FM you would be better off going to a gain antenna like the M^2 2m9 that can be turned with a small TV antenna rotor. If you were operating CW/SSB then the amp is worthwhile because it can lift your signal from not there to just under the noise and copyable.
I think you're getting too wound up about this, OM. The fact is that 3dB will rarely make much of a difference, but there is a difference (as many of us have already said). But hams are impressed by power, and a 110 watt radio would sell better than a 100 watt radio, too, if the price was the same.
Originally Posted by WA8KJP
There is nothing wrong with wanting more power, but everything has a cost/benefit ratio to be considered. If an additional 3dB adds considerably to the cost, then that has to be factored in. I don't think there is anyone out there that can't do as well with 100 watts as they can with 200 watts, it just might take a little longer to score DXCC or contact some rare station, or it might account for a slightly lower QSO count in a contest. That's about it. There will be no "night and day" performance improvement with a 3dB increase.
The definition of an S unit is a 5 to 6 dB improvement in signal. Whether or not any particular radio has a meter that performs to those exact specifications is moot. There are probably some on the market that are pretty close, maybe even a few made decades ago.
Apparently, Kenwood has not consulted with the ham radio experts about the folly of making a separate radio that has only 3 db (1/2 S unit) more output compared to an otherwise identical radio putting out 3db less power. And by the way I have never seen any evidence that there was ever a receiver made in history that had an S meter that had exactly 6 db increments between S0 and S9. If you know of one, show the proof you have from a legit test.
We cannot tax our way to prosperity.
The responses to the original OP is in relation to his misunderstanding that tripling your power does not triple the strength of your signal at a distant receiver nor does it triple the distance you can effectively communicate. The db reference is to show exactly why that is a true statement. We aren't talking theory these are proven facts and explain why things operate the way they do. Yes 3 db will squeak a little bit more out of a signal and maybe make it one that can now be copied. A little increase in power may bring a CW signal that added bit to be copied just in or above the noise. It will not make a world of difference as far as overall improvement but if it just gets that tiny little bit more that's okay. It is not worth it to open up your rig and crank the power output up to 125 watts from the 100 watts normally rated output. The gain may cause a more rapid failure of the final devices and unless someone over engineered it that's the most likely outcome.
I look at it this way--it is a tough climb to get to the first 100 miles, then it gets much easier to improve your range, until you get to 250 miles, where it gets tougher again. Most FM stations don't have a typical range of 100 miles--which is why most posters say an amp won't help much. But, near 100 mile range isn't too hard for a SSB/CW station with a beam--so an amp is much more useful, even though the power gain is the same. Working distant repeaters doesn't count--it is easy to work the Mt Greylock repeater from 100 miles with a handheld because the repeater does all the work.
Working weak signal level CW or SSB as I often do, 3dB is a big deal. S/N ratio is a big deal. Going from 100W to 200W can be a big deal.
On FM - different story in terms of how "useful" small increments of gain are. Perhaps take away 3dB and you can no longer "kerchunk" the repeater. I never heard anyone on V/U FM go from "barely making the repeater" to "near full quieting" with only 3dB.
I've had plenty of contacts on SSB/CW where 3dB would have been make or break.
Not so much on FM modes.
Last edited by K1DNR; 08-14-2012 at 10:05 PM.
How high is your antenna? Raising mine 12' was almost exactly the same as going from 30W to 75W, the difference of course being that I can hear better now too.
Depends on what's around you, but if there's anything within 1/2 mile or so that's higher than 25 feet, raising the antenna can make a world of difference.
Originally Posted by KT4JX
Often, much more than increasing power.
A government which robs Peter to pay Paul can always depend on the support of Paul.
-- George Bernard Shaw
Originally Posted by WB2WIK
Could you be a bit more specific about your "73 Article?" the "Archives.org" site is a bit overwhelming.