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

[David Wise]

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
>