[TenTec] Omni VII Digital

[George Fritkin via TenTec]

Only half right. In RF yes 50 ohms is used, but for audio it is 600 ohms

George, W6GF

Sent from my iPad

> On Aug 12, 2014, at 6:27 PM, Carl Moreschi <n4py3 at earthlink.net> 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 at blomand.net>
>> To: "Discussion of Ten-Tec Equipment" <tentec at 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 at gmail.com> wrote:
>>>> 
>>>> 
>>>> BLACK = pin 3, push to talk
>>>> Ground from the 46176 cable is connected to pin 2.
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>> 
>> 
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