[Kenwood] R5000 "S" meter - AGC alignment problem

[Phil Atchley]

Hello
On my Kenwood R-5000 I've gotten tired of looking at an "S" meter that read
S2 with no signal (or antenna)and S9+ on even fairly weak signals (in other
words way out of calibration).

So I dug out the service manual, warmed up the signal generator (a
reasonably accurate Clements SG-83C) and decided to align the "S" meter
circuit.  This set had previously been to a service center just before I got
it.  Looks like the VCO's have been re-done with nice fresh hotglue :)
Anyway, I did the following adjustments with indicated results.

SIGNAL GENERATOR NOTE:
The attenuator settings on my generator show 32 dBu (what the manual calls
for) as 40uV??? My Generator outputs 1uV at 0dB attenuator(all attenuators
inserted) setting.  IF I read this right, 32dBu 'should' have 32 dB removed
(all are slide switches in 4,6,10,20 dB steps, 100dB total) The manual says
that the S meter should read uV on the lower scale.  This receiver shows S9
as 20uV, not 40uV.

NOTE:  I DID NOT align the BP filters, IF strip etc as I don't have the
proper sweep generator.  As a long time technician I don't tweek just to
tweek.  I limited myself to the following.

1.  Set the "IF Shift" pot VR6 to 1.1Volts per Other adjustment Step 5.
RESULTS:  IF shift is now centered properly, it was all cockeyed.

2.  Set the "Carrier Point" Pot VR7 for same LSB/USB sound per step 18.
RESULTS:  LSB & USB have the same "tonality".

NOW TO THE S METER.
I did the preliminary adjustements in step 19 where you adjust the
following.
14.1MHz, USB, Fast AGC.
1.  Adj VR2 for 2.9V at TP3.
2.  Turn VR3 to max.
3.  Short TP4 & TP5 together.
4.  Adj VR4 so S meter reads S2.
5.  Adj VR2 for 3 Volts at TP3
6.  Remove short from TP 4 & 5.
7.  Input 32dBu from Sig Gen, AF output 1kHz.
8.  Adj VR3 for S9 on meter
9.  Adj Signal Generator to 10dBu.  Adjust VR1 for S2 on meter.
Repeat steps 7-9.
ALL the preceding steps go well!

Now, this is where I get problems.
Step 20 D-AGC

Adj generator to 92 dBu.  Adj VR5 for S meter S9+60.  Can't do it!

NOW, even though the AGC 60dB point doesn't want to set properly, the S
meter is MUCH BETTER BEHAVED, with most signals reading about what I'd
expect.  BUT, really strong signals (like local BCB) "peg" the S meter while
I expect they should read perhaps +60 or a litle less.  It is very
non-linear above S9.  Example:  Set the Sig gen for S9 (32dBu) then remove
20 dB of attenuation, instead of reading S9+20, the meter reads S9+40!

73 de Phil  KO6BB
DX begins at the Noise Floor!
ko6bb@elite.net
Merced, Central California
37.18N  120.29W CM97sh


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