[Racal] Racal 6790 IF Gain Control

[Al Klase]

Racalistas,

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

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

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

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

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

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

I hope this helps a little.

Regards,
Al


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