Re: [Discuss-gnuradio] Microtune 4937 RF module discontinued ...

[Ian Wraith]

Hello

> I need some such a kind of downconveretor too !
> i got a commercial PAL tv tuner which has an IF in 45MHZ , so i need to 
> mix it down to fit in the PCI-DAS4020 bandwidth , i tried some mixer and 
> oscillators such az ne612 va .., but i could not succeed cause i'm not a 
> RF designer . any way i need  it too !

 Many years ago as a student project I built a spectrum analyser by using
an old style voltage tuned TV tuner (they are all I2C controlled now). That
had a 39 MHz (ish) IF which needed reducing to 10.7 MHz. For that I used a
SBL-1 diode mixer module from Mini Circuits which are pretty cheap and
a 1 transistor 28 MHz crystal oscillator. When that was connected to the
mixer and the TV tuner IF to the other end out would come a 10.7 MHz IF.
If I remember correctly I used a couple of 3db attenuator resistor pads
to ensure 50 ohms impedance was presented to the SBL-1 but it was simple
enough.

 For more info on Mini Circuits mixers have a look at ..

http://www.minicircuits.com/appnote/mxr1-25.pdf

Regards

Ian