On Mon, 23 Feb 2004 10:28:19 GMT, Doug Smith W9WI
wrote:

Tom Holden wrote:
In researching desirable AGC characteristics that might be applied to the RS
DX-394 over a year ago, I came across the terms 'delayed' and 'hang'.
Thought they were interchangeable but on reading the ARRL 2004 Handbook, it
seems that 'delayed' means that the attack speed on the RF stages is slower
than on the IF stages or is relatively delayed. According to the HB, "This
prevents a premature increase in the receiver noise figure".

I always thought "delayed AGC" means that there's no gain reduction
unless the strength of the incoming signal reaches a certain threshold.
It's not a delay in time, but in amplitude.

Yes, this is correct for the proffesionals, a certain amplitude level
must be reached before the AGC threshold is hit, while amateurs
started to talk about time delay, rise and fall times when AGC was
optimized for SSB reception. But even receivers designed before WWII
had some degree of mode-dependent time delay optimization, fast for AM
and somewhat slower for CW
I experienced the importance of proper time constant when I tried to
improve the Collins 51-S, see http://home.online.no/~la8ak/b35.htm

73
JM
----
Jan-Martin, LA8AK, N-4623 Kristiansand
http://home.online.no/~la8ak/