[Test-Equipment] spectrum analyzer as radio receiver

[Mark Donaldson]

Gil,

The biggest draw back with using a spectrum analyzer,
frequency selective voltmeter or wave analyzer as a
receiver is lack of AGC, which most of the previously
mentioned instruments will not have. My suggestion is
to look for a good used receiver that covers the
frequency range you are interested in, such as
something from Watkins Johnson or Racal, the prices on
these are reasonable and plenty are hitting the
surplus market.

Mark 
--- gil smith <gil@vauxelectronics.com> wrote:
> Hi folks:
> 
> I have been wanting to get a radio receiver to
> search for some rtty
> signals, but not quite knowing what I am looking
> for, and not wanting to
> shell out the money just yet, I have been pondering
> some budget alternatives.
> 
> One such wacky thought was to use a spectrum
> analyzer as a radio receiver.
> So I dug out some manuals and fired up my 141T
> mainframe, currently
> populated with the 8554L 1250MHz RF, and 8552A IF
> sections.  I just stuck a
> little whip antenna on the rf input.  Sure enough, I
> can find a signal
> spectra, set the scan-width to ZERO, and fine tune
> the signal and see the
> time-domain representation on the crt.
> 
> So I hung a scope on the vertical-output from the IF
> section, and saw a
> similar (perhaps inverted) signal.  I stuck some
> amplified headphones on
> the vertical-out, and heard some noise.  Tuning
> around, I found music up
> around the FM band!  This brings up my first
> question:  I expected to just
> get AM reception, so what am I hearing just over 100
> MHz?  This can't be
> demod-ing FM stations, can it?
> 
> I found some more broadcast-like programs around
> 550MHz, found some data
> (nicely demodulated) in various spots, and lots of
> undecipherable stuff
> around 900 MHz where phones and things make noise. 
> Didn't find much below
> 100MHz, but the antenna is only 6".  
> 
> I also have an 8553B 110MHz RF section that I did
> not yet try, which would
> likely benefit from a better antenna choice for
> lower freqs.  And I have
> the companion Track-Gen/Counter -- would this
> provide a freq readout when
> in zero-scan mode with the 8553?  Or, is there a way
> to use an external RF
> signal generator to select carrier freq?
> 
> yeah, it's late -- any thoughts appreciated,
> 
> gil
> 
> 
>
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