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Re: [Amps] power and db

To: AMPS <amps@contesting.com>, Paul Kraemer <elespe@lisco.com>
Subject: Re: [Amps] power and db
From: Glen Zook <gzook@yahoo.com>
Reply-to: gzook@yahoo.com
Date: Wed, 4 Feb 2009 09:36:49 -0800 (PST)
List-post: <amps@contesting.com">mailto:amps@contesting.com>
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@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.


      
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