I didn't realize the discussion was about audio.
0 DBM is defined as 1 milliwatt.
At 600 ohms, that's 0.77 volts for 0 dbm.
S9 is -73 dbm so 0 dbm is S9+73.
-10 dbm is .1 milliwatt.
-20 dbm is .01 milliwatt
-30 dbm is .001 milliwatt
-40 dbm is .0001 milliwatt
-50 dbm is .00001 milliwatt
-60 dbm is .000001 milliwatt
at 600 ohms, -60 dbm is .024 volts or 24 millivolts.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
On 8/12/2014 9:27 PM, Carl Moreschi wrote:
0 DBM is defined as 1 milliwatt.
At 50 ohms, that's 0.22 volts for 0 dbm.
S9 is -73 dbm so 0 dbm is S9+73.
-10 dbm is .1 milliwatt.
-20 dbm is .01 milliwatt
-30 dbm is .001 milliwatt
-40 dbm is .0001 milliwatt
-50 dbm is .00001 milliwatt
-60 dbm is .000001 milliwatt
at 50 ohms, -60 dbm is .007 volts or 7 millivolts.
Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com
On 8/12/2014 9:06 PM, Bob McGraw - K4TAX wrote:
Someone asked about "what's a value of -60dB in terms of voltage?"
Well if I did the math correct:
- 60 dBv = 0.001 volts or 1 millivolt
-30 dBv = 0.031 volts or 31 millivolts
-20 dBv = 0.100 volts or 100 millivolts
+20 dBv = 10.0 volts
73
Bob, K4TAX
----- Original Message ----- From: "Robert" <rmcgraw@blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Tuesday, August 12, 2014 9:20 AM
Subject: Re: [TenTec] Omni VII Digital
Louis brings up a good point on audio levels. There are 3 basic audio
level groups.
They are:
(a) MIC level typically -60 dB to - 30 dB
(b) Line level typically -20 dB to +20 dB
(c) Speaker level - usually several volts depending on power in watts
and impedance.
Thus the levels ranges of (a), (b) and (c) should not be expected to
be connected directly, one to another, without some specific means to
correct levels to the proper range.
Thus connecting a speaker level output direct to a mike input can
damage the mike input components. And the same for speaker output
level to a line input.
Don't worry about "matching impedances" as systems today operate as
voltage sources and loads. Except when using power amps driving
speakers to attain efficient transfer of power.
Plus interconnecting levels of the same range will assure the best
Signal-to-Noise ratio.
Interface devices such as the Tentec 712 USB Soundcard interface or
the SignaLink USB interface are good choices to interconnect systems
and levels.
73
Bob K4TAX
Sent from my iPhone
On Aug 12, 2014, at 8:53 AM, Louis Ciotti <lciotti1@gmail.com> wrote:
BLACK = pin 3, push to talk
Ground from the 46176 cable is connected to pin 2.
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