[R-390] Call for measurements - 100dB carrier reading

[Graham Baxter]

Hi Dave,

I will do this tomorrow morning. Its bed time here !

Graham

On 23/08/07, David Wise <David_Wise at phoenix.com> wrote:
> Hi Graham,
>
> I'm alluding to the standard TM11-856A procedure for
> setting the IF gain.  You put 150uV 455kHz into J513 in
> MGC, and set R519 for -7V on the Diode Load terminal.
> Doesn't matter how you achieve 150uV; I did it by putting
> in 1.5mV (which I *can* measure) then turning the gen
> down 20dB.  That gets you around the termination uncertainty.
> Setting the gain is just to ensure we are comparing
> the same thing.  The open-loop IF gain affects the
> closed-loop error aka AGC.  For the actual AGC measurement,
> put in anything you want, really; I'll follow and compare.
> 100mV sounded convenient.
>
> Dave
>
> > -----Original Message-----
> > From: grahambaxterdelphe at googlemail.com
> > [mailto:grahambaxterdelphe at googlemail.com]On Behalf Of Graham Baxter
> > Sent: Thursday, August 23, 2007 1:00 PM
> > To: David Wise
> > Cc: r-390 at mailman.qth.net
> > Subject: Re: [R-390] Call for measurements - 100dB carrier reading
> >
> >
> > Hi Dave
> >
> > I can confirm that I used a DVM with a 10 Meg input impedance.
> >
> > Can you clarify; do you want the 150uV applied to the input
> > of the IF module?
> >
> > If so, would you like me to arrange the 150uV across a fifty ohm
> > through termination and assume the loading of the IF is negligible? I
> > ask this because I can't easily measure 150uV in other than 50 ohms.
> >
> > Graham
> >
>