Re: +7dB from BFO to diode ring mixer?




hi.
it's not dB, it's dBm and it's a measure of power. the diode mixer has
a finite input resistance (read also impedance). as such a voltage
applied to its input causes power to be generated and consumed there. 0
dBm is defined to be 1mW of power into 50 ohms. 7dBm equates to 5mW of
power into a load of 50 ohms. this amounts to 500mV RMS, or
approximately 1.5 volts PTP across 50 ohms.
so you have to produce 5 mW of power to drive a regular DBM . there are
also special ones requiring up to 50 mW or more for proper performance.
Hope it helps:
Saandy 4Z5KS





aadu.adok@xxxxxxxxx wrote:
hello,

can someone please explain me, what does it mean that DBM diode ring
mixer expects +7dB from BFO?

I do understand that from BFO comes out some peak-to-peak voltage (2.2
volts for example).
But how does it scale to +7dB?

thanks

.

Relevant Pages

  • Re: DTMF ENERGY LEVELS
    ... The unit dBm is for decibels normalized to 10mW of power. ... uses 900 ohms for residential circuits and 600 ohms for commercial ... Also don't forget that the DTMF spec is designed for a clear channel ...
    (comp.dsp)
  • Re: Calculation of snr
    ... I don't agree that dBV is dimensionless - yes, it is a ratio of voltages ... but you could not equate dBV with dBm or dBA. ... Weighted absolute noise power, ... dBv does not define a voltage, it defines a "dB" value, ...
    (rec.photo.digital)
  • Re: Calculation of snr
    ... voltages but you could not equate dBV with dBm or dBA. ... a voltage level. ... the ratio of a power at a particular impedance to the power from a ...
    (rec.photo.digital)
  • Re: Calculation of snr
    ... voltages but you could not equate dBV with dBm or dBA. ... the ratio of a power at a particular impedance to the power from a ... voltage level and not a sound pressure level or power level or a ...
    (rec.photo.digital)
  • Re: Long Range Wireless Network
    ... would end up to the +36 dBm EiRP transmit power. ... Which puts you right at the legal limit for the U.S. If your transmitter ...
    (rec.radio.amateur.homebrew)