Jose -
There are a couple of AGC setup 'rules'. One just says to set R1127 'fully clockwise' and then
never mentions it again. This is the AGC 'delay' setting, think the -1.34 VDC setting in the 4
series. This is the 'threshold', and the idea is to turn the AGC 'on' just slightly so it doesn't
'step' on , but rather just increases smoothly when a signal appears.
With no antenna, and the IF GAIN (R1138) fully counterclockwise, adjust R1127 counterclockwise until
the output noise JUST decreases. This tells you that the AGC is 'on', just barely.
The reason MEDIUM and SLOW 'look' better is that the AGC doesn't have time to get all the way back
to ZERO before the next syllable comes along.
Maybe someone else has a better explanation, but this is what works for me!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Jose V. Gavila wrote:
Hi all,
Thanks everyone for your help on this!. I have realigned the AGC and now it is better, even if not
as good as I would like, as there is an slight cracking noise still sometimes on SSB and, on CW,
with AGC set on FAST, the effect, as seen on an oscilloscope connected in parallel with the
speaker, is very noticeable (as a distorted envelope). MEDIUM and SLOW 'look' lots better.
If I set AGC OFF and reduce RCVR GAIN, all is OK, so it really seems as an AGC
problem.
Regards,
JOSE
--
73 EB5AGV - JOSE V. GAVILA - IM99sm La Canyada - Valencia(SPAIN)
Radio and Test Equipment....... http://jvgavila.com
RadioRepair BLOG............... http://radiorepair.blogspot.com
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