[time-nuts] OT favorite signal generator?
brooke at pacific.net
Fri Jun 19 11:52:29 EDT 2009
There are a bunch of signal sources that could be used.
The rack sized HP signal generators that weigh 50+ pounds were designed to have
very low phase noise and although now many years old are still very good for that.
The HP 3325() is the only signal generator that has adjustable amplitude that's
calibrated to a small fraction of a dB. They still are the specified
instrument for amplitude calibration of many other pieces of lab equipment and
there is no newer instrument to replace them. They don't have good specs in
the frequency domain.
The HP 8648() series are reasonably small and light synthesized signal
generators. I got the 8648A Option 1EP which is specific for pager testing and
includes many modulation enhancements. The prior versions of the 8648 did not
have good enough specs to test pagers.
A problem with injecting a signal into operating equipment is you may burn out
the signal generator. For example just touching a DC point feeds a step change
back into the sig gen. So it's good to have a series resistor and blocking cap
to protect the sig gen.
You might be able to use a probe that generates something like narrow pulses at
an audio rate as a universal signal source.
> Hey everyone
> Sorry for the off topic post. I have received great advice in the past
> with items for my little shop and I can't resist to ask again.
> I am thinking about buying a signal generator. I suspect that I will
> mostly use it to inject low uV/mV signals into the amplification stages
> of the laboratory instruments I service.
> Any feedback you have would be greatly appreciated-Patrick
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