[Amps] power and db

[Glen Zook]

Using the "olde tyme" figure of 1 "S" unit = 6 dB your figures are correct.  Unfortunately, on many "modern" transceiver "S" meters that 3 dB increase in power can equate to several "S" units.

A while back the various equipment manufacturers got into a "war" claiming that their equipment was more "sensitive" than the other manufacturers' equipment.  What they did was to decrease the signal level required for an S-9 reading from the "standard" of 50 microvolts to a signal level of 10 microvolts or less.  Then the "dB over" readings bear no relation to the 20 (log (V1/V2)).  Instead of the "olde tyme" 20 over requiring 500 microvolts, 40 over requiring 5000 microvolts, and 60 over requiring 50,000 microvolts I have measured a number of "modern" equipment requiring as little as 100 microvolts for a 40 over reading!

As such, just a relatively small dB increase in power can result in a large "S" meter reading increase.

Glen, K9STH

Website:  http://k9sth.com


--- On Wed, 2/4/09, Paul Kraemer <elespe at lisco.com> wrote:

Did I miss something in school? Probably. All the discussions on modifying linears for a few more watts seems ridiculous, or at least frivolous. db=10 log P1 /P2 still applies doesn't it? Double the actual output power rating of that fine L 4 or SB220 from 1000 w to 2000 w will only increase your signal strength on the receiving end by 3db, 1/2 s unit. IF you could increase your output fourfold, 4000 watss output (that would be illegal) you would only gain one S unit. Attempt to do either and you will only exponentially increase your problems. Have all the fun you want but increasing output on a kw linear by a couple hundred watts just doesn't improve anything. Like the man says, work on your antenna where you can make a difference. And, if you are really disappointed with that L4 or SB220 you could send it here. I'd like it just the way it is.