[ARC5] Visual alignment connections

[Ian Wilson]

Hi Ken,

Rule 1 of explaining the unexpected is that the test gear is
somehow interacting with the unit under investigation. So I
wonder whether your troublesome connections are somehow
producing feedback (i.e. oscillations) and that is producing
the results you are observing.

73, ian K3IMW



On Thu, May 23, 2013 at 8:11 PM, Kenneth G. Gordon <kgordon2006 at frontier.com
> wrote:

> Well, I am still very confused by what I have read concerning connection
> of a
> Frequency Modulated signal generator to a receiver and viewing the output
> on a 'scope.
>
> According to every single book and article I have read over the past few
> days
> on this subject, they ALL show the "Y" axis of the scope connected
> directly to
> the diode load at the "2nd detector" and a synchronizing signal fed to the
> scope's external "X" input or to its external horizontal sweep input.
>
> All of those photos and drawings all show the outline of the IF passband
> appearing exactly as one can see in my Photos 2, 3, and 4.
>
> Yet, every time I try to connect my equipment the way those other books and
> articles show, the results are most decidely NOT the "outline of the IF
> passband". Most of the time there is simply nothing recogizable seen.
>
> ALL of those documents by so many different outfits cannot ALL be wrong
> the same way!
>
> The only way I can get what I want is to use (as John Forster
> mentioned....more than once) an RF probe with an LP filter included,
> removal of the 2nd detector tube completely, and connection to the input of
> the detector diode at the output of the last IF transformer.
>
> Might anyone have even a clue as to what in the heck is going on here?
>
> I might add that I have connected a standard scope probe to the same point
> I connect my RF probe. What I get on the screen is a vertical double-image,
> one up and one down, "filled in" but with the outline identical to what I
> see
> with the probe alone in place.
>
> Kenneth G. Gordon W7EKB
>
> "Courage is being scared to death but saddling up anyway."--- John   Wayne
>
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