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


"Rocco Lardiere"  made an utterence
to the drakelist gang
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Steve,

I assume you have performed an alignment per the manual.  If you have, =
you might try repeating it just to be certain.  The noise blanker will =
affect gain (if well aligned, it may actually increase the gain a bit - =
if not, try taking it out of line).  If you still have the problem:

You may have a gain problem somewhere in there.  The easiest way to find =
it is to use a scope and compare stage gains one by one with a known =
good R-4C (with the AGC off).  This could be a bad cap, resistor, tube, =
etc. =20

To be certain you DO have a problem, use a known good signal generator =
through an attenuator for impedance matching.  You should be able to =
pass the gain tests per section 5-13 of the manual.  Don't depend on the =
calibrator or off the air tests to check gains.  That's where calibrated =
test equipment will be of real use.  I hunted down a couple of HP 8640B =
generators at the TRW swap meet for this exact application - and value =
them highly. =20

73,

Rocco N6KN
  ----- Original Message -----=20
  From: stephane.mazzoni=20
  To: drakelist{at}www.zerobeat.net=20
  Sent: Thursday, November 04, 2004 5:34 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 =
sufficiently
  Reference : S/N 18518 DRAKE R-4C "4-position mode switch"

  Dear friends,
  I've corrected the dial gear problem. here comes another one :
  I've investigated a lot on this receiver during this week-end and =
would like an advise for diagnosing and correcting the S-meter =
sensitivity which I found insufficient.

  Best 73s and thanks for your suggestions,
  Steve.

  ________________________________________________

  1. Context
  This R-4C (4-position) is equipped with the AM filter, the two 250 and =
500 Hz CW filters and the 4-NB noise blanker. It is combined with a =
T-4XC S/N =3D
  28513 and an MN-2000 matching network.
  The antenna is a FRIETZEL Conrad-Windom wire antenna type FD-4.
  All wafer tracks and sockets as well as all pins have been fully =
cleaned.
  I do not have the chance to get access to any RF generator or =
lampmeter, =3D
  however I can make comparisons with a KENWOOD TS-930S.

  2. What is observed :
  Even with the strongest signals heard on 3,5 and 7 MHz bands, the =
S-meter would not go higher than S9 + 10 dBs on the strongest signals =
(i.e. broadcasting stations on 40m).
  On the other hand, the actual sensitivity seems to be good on all =
bands with respect to the TS-930S rx : i.e. the smallest signals that =
can be heard on the TS-930S seems to be also audible on the R-4C.
  A difference of more than  20 dB on S-meter readings is experienced =
=3D
  between the two receivers.
  The AGC time constant selection switch on front panel of the R-4C =3D
  operates normally.

  For reference, the Xtal calibrator signal is :
  S9 on 7000 kHz,
  S9+10 on 7025 kHz,
  S9+5 on 7050 kHz,
  S9+10 on 7075 kHz,
  S9+5 on 7100 kHz.

  The 80m noise level at night is around S6/S7 and the strongest =
stations would not deviate more than S9+5.
  On the STBY position of the Function switch, the S-meter deviates to =
S9+35dB.

  3. What has been learnt from the documentation about the AGC and =
S-meter settings :
  There are three possible adjustments :
  a) The "zero setting" of the S-meter, R-32, on the rear panel, which =
should be adjusted for S-3 with a 1 microVolt RF generator input.
  b) The "bias setting" of the AGC, R-55, which should be adjusted for =

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