# [Amps] Power expressed in db

realex realex at flash.net
Tue Feb 11 18:49:06 EST 2003

```Just found my typo...   63 is 2000 Watts

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
Behalf Of realex
Sent: Tuesday, February 11, 2003 5:44 PM
To: WYsixK; amps at contesting.com
Subject: RE: [Amps] Power expressed in db

The power ratings are most likely in dBm (dB milliwatt).
10 dBm = 10 X .001 Watt = .01 Watt
20 dBm = 100 X .001 Watt = .1 Watt
30 dBm = 1000 X .001 Watt = 1 Watt
so.... 40 dBm = 10 watt,  50 dBm = 100 Watt,  60 dBm =1000 Watt
every 10 dB increase = 10 X increase in power.
3 db increase = 2X the power so 63 dBm = 1500 Watts (1000 + 500)

An amp with a rated 30 dBm input and 13 dB gain would have 20 watts out with
1 Watt drive.
Likewise, an amp with a rated input of 50 dBm and 13 dB gain has 1500 Watts
output

Hope this helps,
73, Bob, W5AH

-----Original Message-----

I see some solid state amps specified in such a way that the input
signal level is expressed in db.  Then the gain is expressed in db etc.
How does one relate this db scale to power in watts?

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