hi. i have a DVB TV that works in frequency 6-8 MHz . i want to make a circuit that shifts another rang of frequency to this rang. (something like 8-10 MHz to 6-8 MHz).
what can i do ?

 

use a local oscillator of 2 MHz, which when mixed with your signal will create the freq you desire. You will then need to band pass filter your mix to isolate the freq.

Alt method. receive and remove the data from signal, then re-modulate the desired freq with the data and transmit that for reception by your TV(or whatever)

 

I'm going to shift frequency between 8-10 MHz to 6-8 MHz, do you think that mixing input signals with signals comes from oscillator (2 MHz) can cause decrease signal frequency ? and, whats the rule of band pass filter ? is it necessary ?
[is it possible for you to make a simple scheme of this circuit ? ]