[Racal] RE: Racal 6790 IF Gain Control

[Paul]

Wow! Thanks Al! As soon as my sick 6790 is healed I'll give it a try.
Thanks again
Paul

-----Original Message-----
From: Al Klase [mailto:skywaves@bw.webex.net]
Sent: Wednesday, January 08, 2003 5:15 PM
To: Paul
Cc: Dan Rae; Robert Thompson; Racal RA6790gm
Subject: Racal 6790 IF Gain Control


Racalistas,

I had to go play with the radio to answer Paul's question.=20
(..what DOES that thing do??!!)

This knob serves the same purpose as the RF-gain control in=20
a normal receiver, but because there is no RF amplifier it's=20
labeled IF-gain.

There are three modes of operation.  These are my=20
designations not Racal's:

AUTOMATIC: "MAN" indicator is off.  Pre-detection gain is=20
controlled automatically.  Time constant is selected by the=20
"SHORT" "MED" and "LONG" buttons. "IF GAIN" has no effect.

AUTOMATIC WITH THRESHOLD:  "MAN" indicator is on as a result=20
of pressing the "MAN" button.  One of the time constant=20
indicators("SHORT" "MED" "LONG")will be on. The output of=20
both the IF-Gain pot and the AGC circuit are applied to the=20
IF amp.  Reducing "IF GAIN" will suppress weak signals (or=20
noise), but AGC still functions for signals stronger than=20
the "threshold" indicated on the S-meter.

MANUAL:  "MAN" indicator is on.  All time constant=20
indicators are off.  This mode is entered from the=20
automatic-with-threshold mode by depressing the=20
time-constant button associated with the time constant=20
indicator that is on.  Gain is controlled only by the=20
IF-gain control.  S-meter indicated the amount of gain=20
reduction.

I hope this helps a little.

Regards,
Al


--=20
Al Klase - N3FRQ
skywaves@bw.webex.net
Flemington, NJ 08822
Web Page:  http://www.webex.net/~skywaves/home.htm