Hi.
Somewhere, perhaps this forum, decades ago, someone put an antenna to the output of a channel 3 TV RF modulator gadget and received the signal short range over-the-air within dwelling televisions.
What is the RF output level supposed to be ?

 

Google AI states:
"For a standard NTSC analog TV RF input, the ideal signal level at the tuner ranges between 0 dBmV and +15 dBmV (roughly 60 to 75 dBμV) into a 75-ohm impedance, with +3 dBmV to +10 dBmV being the operational sweet spot for a clear, snow-free picture."
so I would expect the modulator output to be within that range.

Since you want to abolish the deciBel, I'll translate:
10dBmv is approximately 3.1mV.

You do realize that it outputs an NTSC analog standard definition signal, not the ATSC digital high-def format, so you have to check if your TVs can accept that.

If you want a high-def ATSC modulator, those appear to be at least an order of magnitude more expensive.
Alternately you can buy HDMI wireless transmitters with more than one receiver.

 

The amplitude of the RF output of one of those RF adapters (they are not really "modulators") is quite low. .
It does not bear any relation to the standard amplitude of an analog composite video signal, which I have measured on a scope to be about one volt. (several years ago) The FCC regulation used to have the limits at 100 MILLIWATTS.

 

they are not really "modulators"

Don't understand why you say that(?).
They modulate the output RF with the video and audio inputs to the NTSC standard.

 

A "modulator" is the portion of a circuit that usually modulates an RF signal. So those are "RF Interface " devices, or "micro-transmitters".
Certainly they may deliver a modulated RF signal, but to call them a"modulator" is not corect, technically. Modulator without a signal source to be modulated is certainly an incomplete system. YES, it is a commonly used term among those unwilling to provide a complete description.

 

A "modulator" is the portion of a circuit that usually modulates an RF signal

That's exactly what that modulator circuit does.
Why do you think it doesn't?

Modulator without a signal source to be modulated is certainly an incomplete system

That makes little sense.
The signal source (the video and audio) is not what's modulated.
The RF generated by the modulator's internal oscillator is being modulated by the signal source.