Homebrew Spec Analyzer question

Homebrew Spec Analyzer question

Post by Bria » Thu, 05 Jul 2001 21:43:25

I was given a older (circa '92) satellite receiver (working when last
used) that has a 950-1450Mhz varactor tuner in it.  Questions:

Given the variety of homebrew spectrum analyzers using CATV and UHF
varactor tuners, is it possible this 950-1450 Mhz tuner has some
promise?  

Would it be terribly difficult to use the 70Mhz IF output in such a
design without special support chips?

Thanks in advance.

Brian

 
 
 

Homebrew Spec Analyzer question

Post by Peter J. Bertin » Thu, 05 Jul 2001 23:20:00


The 70 MHz is just about where you would want it.

I'd use a simple bandpass filter, followed by an inexpensive
DBM to bring the IF down to the 10.7 MHz range where you
could use cheap ceramic and LC filters to set the bandwidth.

Do you know the LO range, and whether if it is high or low side
injection?  You will have to do some modification of the tuner's
frontend,  and perhaps the VCO,  to get HF/VHF coverage.

Pete


Quote:> I was given a older (circa '92) satellite receiver (working when last
> used) that has a 950-1450Mhz varactor tuner in it.  Questions:

> Given the variety of homebrew spectrum analyzers using CATV and UHF
> varactor tuners, is it possible this 950-1450 Mhz tuner has some
> promise?

> Would it be terribly difficult to use the 70Mhz IF output in such a
> design without special support chips?

> Thanks in advance.

> Brian

 
 
 

Homebrew Spec Analyzer question

Post by Pete Gianakopoulo » Tue, 10 Jul 2001 12:54:30

Bob Werth, down in St. Louis, Mo. had several 70MHz SAW filters on hand; you
might want to contact him.

Pete Gianakopoulos  KE9OA



> The 70 MHz is just about where you would want it.

> I'd use a simple bandpass filter, followed by an inexpensive
> DBM to bring the IF down to the 10.7 MHz range where you
> could use cheap ceramic and LC filters to set the bandwidth.

> Do you know the LO range, and whether if it is high or low side
> injection?  You will have to do some modification of the tuner's
> frontend,  and perhaps the VCO,  to get HF/VHF coverage.

> Pete



> > I was given a older (circa '92) satellite receiver (working when last
> > used) that has a 950-1450Mhz varactor tuner in it.  Questions:

> > Given the variety of homebrew spectrum analyzers using CATV and UHF
> > varactor tuners, is it possible this 950-1450 Mhz tuner has some
> > promise?

> > Would it be terribly difficult to use the 70Mhz IF output in such a
> > design without special support chips?

> > Thanks in advance.

> > Brian