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





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