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From: | Ian Wraith |
Subject: | Re: [Discuss-gnuradio] Microtune 4937 RF module discontinued ... |
Date: | Fri, 18 Jul 2003 15:59:36 +0100 |
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
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