From: "Rocco Lardiere" 
Subject: Re: [drakelist] DRAKE R-4C restoration - S-meter may be not
deflecting sufficiently

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  ----- Original Message
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  From:=20
  stephane.mazzoni">mailto:stephane.mazzoni{at}wanadoo.fr">stephane.mazzoni
=

  To: drakelist{at}www.zerobeat.net=">mailto:drakelist{at}www.zerobeat.net">drakelist{at}www.zerobeat.net=
 
  Sent:
Thursday, November 04, =
2004 5:34=20
  AM
  
Subject: [drakelist] DRAKE R-4C =

  restoration - S-meter may be not deflecting sufficiently
  
   
  Subject : DRAKE R-4C restoration - S-meter may be not deflecting=20
  sufficientlyReference : S/N 18518 DRAKE R-4C "4-position mode=20
  switch"Dear friends,I've corrected the
dial gear problem. =
here=20
  comes another one :I've investigated a lot on this receiver during =
this=20
  week-end and would like an advise for diagnosing and correcting the =
S-meter=20
  sensitivity which I found insufficient.Best 73s and
thanks for =
your=20
  =
suggestions,Steve.___________________________________________=
_____1.=20
  ContextThis R-4C (4-position) is equipped with the AM filter, the =
two 250=20
  and 500 Hz CW filters and the 4-NB noise blanker. It is combined with =
a T-4XC=20
  S/N =3D28513 and an MN-2000 matching network.The antenna is a =
FRIETZEL=20
  Conrad-Windom wire antenna type FD-4.All wafer tracks and sockets =
as well=20
  as all pins have been fully cleaned.I do not have the chance to =
get access=20
  to any RF generator or lampmeter, =3Dhowever I can make =
comparisons with a=20
  KENWOOD TS-930S.2. What is observed :Even with the =
strongest=20
  signals heard on 3,5 and 7 MHz bands, the S-meter would not go higher =
than S9=20
  + 10 dBs on the strongest signals (i.e. broadcasting stations on =
40m).On=20
  the other hand, the actual sensitivity seems to be good on all bands =
with=20
  respect to the TS-930S rx : i.e. the smallest signals that can be =
heard on the=20
  TS-930S seems to be also audible on the R-4C.A difference of more=20
  than  20 dB on S-meter readings is experienced =3Dbetween the =
two=20
  receivers.The AGC time constant selection switch on front panel of =
the=20
  R-4C =3Doperates normally.For reference, the Xtal =
calibrator signal=20
  is :S9 on 7000 kHz,S9+10 on 7025 kHz,S9+5 on 7050 =
kHz,S9+10 on=20
  7075 kHz,S9+5 on 7100 kHz.The 80m noise
level at night is =
around=20
  S6/S7 and the strongest stations would not deviate more than =
S9+5.On the=20
  STBY position of the Function switch, the S-meter deviates to=20
  S9+35dB.3. What has been learnt from the documentation about =
the AGC=20
  and S-meter settings :There are three possible adjustments
:a) =
The=20
  "zero setting" of the S-meter, R-32, on the rear panel, which should =
be=20
  adjusted for S-3 with a 1 microVolt RF generator input.b) The =
"bias=20
  setting" of the AGC, R-55, which should be adjusted for =3DS-1 =
with no=20
  signal at the input.c) the "sensitivity"
adjustment of the =
S-meter,=20
  R-36, which should be adjusted for S-9+60dBs with a 30 milliVolt RF =
generator=20
  input.
  The original settings have not been modified. Except
R-36 for =
test :=20
  at full range of the adjustable, the maximum possible S-meter =
deviation=20
  obtainable will not exceed S9+30 on the strongest stations (i.e. =
broadcasting=20
  stations on 40m). NB : after this test, the setting has been put back =

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