[R-390] Hang AGC Circuit

[Bob Camp]

Hi

The AGC in the R390 has a slower attack speed than more modern AGC 
circuits. A number of people have done a number of things to change 
this. Probably the most common way to go these days is to put a couple 
of solid state diodes and a couple resistors in the AGC. The idea 
usually is to speed up the attack time and leave the decay time where 
it is. The net result is an AGC that cuts in fast and then drops out 
slowly. One term for his is "hang".

The solid state diode mods are no cut, no chop mods. They are easily 
reversed if in the future you decide to go 100% stock. For that reason 
alone I would recommend them over some of the earlier tube based 
designs that involved more surgery to the radio. I do not know if the 
tube versions worked as well as the solid state versions, but it is 
safe to say they did not work any better.

	Enjoy!

		Bob Camp
		KB8TQ




On Jul 17, 2004, at 1:04 PM, Vic/Johanna Culver wrote:

> Sorry -- this originally sent to wrong address.  I hope it doesn't
> duplicate.
>
> Hello, Group. A really good friend gifted me this morning with 
> something he
> said I really needed for my R-390 -- a very competently built "HANG 
> AGC"
> unit. Two tubes, even!. The information indicated that it was from a 
> design
> published in 'the handbook.'  I assume this handbook is an older 
> version of
> the ARRL Radio Amateurs Handbook. Would anyone care to comment on the 
> pro's
> and/or con's of adding a hang AGC unit to a radio -- beyond the fact 
> that
> some of us don't want ANYthing that 'ain't stock.' Thanks, Vic
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.716 / Virus Database: 472 - Release Date: 7/5/2004
>
> ______________________________________________________________
> R-390 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/r-390
> Help: http://mailman.qth.net/faq.htm
> Post: mailto:R-390 at mailman.qth.net
> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>