[R-390] Sweep Generator Alignment

[Bryce Ringwood]

Hi

I have a Philips sweep generator operating at 4 MHZ. You have to have a
signal generator operating 455kHz above or below the 4Mz as input, as
well as a 50 volt sawtooth from a scope timebase. You connect the Rx
detector to the vertical input of the scope and the resulting swept
output from the sweep generator to the IF stages you want to align.
Other sweepers may have a different configuration. Remember that the
selectivity curves presented are usually to a log scale, and your
display will probably be linear. 

I used the setup with a Tek 549 storage 'scope on an AR88, which was
rather upsetting, since all the different selectivity settings peaked at
different centre frequencies when I displayed them on top of one another
:(

Maybe the other listers can give an opinion on whether it would be
worthwhile repeating the experiment on the 390A with its mechanical
filters ?

Have fun with it - Bryce


>>> Jim Brannigan <jbrannig@optonline.net> 09/11/02 11:55AM >>>
A sweep generator is used in conjunction with an oscilloscope to
display
amplitude vs. frequency.  It will present a "picture" of the shape of
a
tuned circuit.
The sweep generator is connected to the input of the device under test
and
the O-scope to the output (through a demodulator).  The sweep generator
is
also connected to the Horizontal input of the scope.

They are commonly used to align fixed tuned circuits, like the 455kc.
IF(or
TV IF).   I don't know how useful a 4Mhz. generator would be since the
signal will have to pass through the entire receiver and this would
not
present a valid "picture" of the IF.
If the price is right they are fun to play with.

Jim


> GE List.  Would there be any benefit to aligning the IF of a 390a or
non
"a"
> using a sweep generator?  If so how would one be connected?  I have
an
> opportunity to pick up a 4mhz sweep/function generator.
>
> thanks for the comments
> Dave Faria

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