[R-390] K5OP AGC Mod & Umodified IF Decks

[Dallas Lankford]

I put an unmodified IF deck in my R-390A a little while ago and measured =
its attack times with a scope using the K5OP AGC mod.  SLOW is awfully =
slow because of the Miller effect circuit it uses.  The SLOW attack time =
was about 200 milliseconds with or without K5OP.  Unacceptable for SSB.  =
The MED attack time with K5OP was unmeasurable because it was an awful =
looking curve, not the exponential curve (or approximately exponential) =
that we need to assign an attack time to.  It probably sounded bad to, =
but I didn't bother to listen.  The FAST setting is unsuitable for SSB.

So there you have it.  The K5OP isn't a stand alone AGC for unmodified =
IF decks.  It is a helper which provides more electrons to give the =
optimal FAST attack needed for the SLOW AGC setting of my (last) AGC =
mod.

When I have referred to my AGC mod, I meant the last one.  I don't =
recall exactly how many AGC mods I published.  Two or three.  (And there =
is another one that I haven't published yet, but it is just a minor =
variation of the "last" one.)  A lot of different people have written =
their versions of my AGC mods, some right, and some wrong.  So you won't =
have to find out the hard way that you have a wrong one, I have uploaded =
my last AGC mod to the FILES section of the other R-390 reflector.

http://groups.yahoo.com/group/r-390/

The access the file you have to register with Yahoo, and then you have =
to join the group.  After you have joined the group, you can click on =
FILES in the side bar, then click on the Dallas folder, and then =
download the file (there are two others, the SSB filter file, and the =
BFO vernier fine tuning file).  The AGC file is BIG, about 3 Megs.  It =
takes a while to download.  It also contains a simple mod to increase =
the BFO injection voltage.  The BFO injection mod may negatively effect =
the AGC voltage.  In that case you should re-neutralize the BFO.  This =
is discussed somewhere on Chuck R.'s web site, I think, and probably =
elsewhere.  I haven't checked this out myself because I never had any =
problems.

The K5OP mod may work with one of my earlier (and simpler) "2 diode" =
mods.  But I probably won't look into that immediately because I have =
other irons in the fire. 

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