[R-390] Initial progress and Questions

[John Kolb]

On Mon, 18 Aug 2003, Roy Morgan wrote:

> At 01:54 PM 8/17/03 -0700, you wrote:
> ... I'd like to take some baseline
> >measurements of sensitivity  ...   What is the preferred
> >method of getting the generator signal into the balanced input
>
> It is overkill, unless you really want to know what's going on at the input
> terminals under balanced conditions.  Likely a simple toroid with carefully
> counted windings would do the job... BUT:  The actual input impedance of
> the radio varies with many factors: band, frequency within the band,
> adjustment of the input circuits, et. al.  Soo, you'd need to arrange a
> swamped termination/input circuit combined with the balanced toroid to
> really know the input voltage with any certainty.
>
> Example: the output attenuator acccessory device supplied with the GR 1001A
> Standard Signal Generator had a division ratio of 100:1* and an output
> impedance of one half ohm*.  Readings indicated on the instrument were
> divided by 100 to get the actual voltage.  The one-half ohm value made
> variations in receiver input impedance have no or little effect on the
> voltage developed.
> * I may remember these values incorrectly, but the basic idea is correct.
>

Sounds like a 49.5 ohm resistor in series with a 0.5 ohm resistor.

John