[Collins] KWM2a, C47

[Ian]

Ref:  Receiver-Transmitter, Radio RT-718/FRC-93 (Collins KWM-2/2A)
Department of the Army May 1976

Identifier 11:  C47, 0.068 uF, has changed value and type.  It has changed
in value (was 0.047 uF) to increase the VOX time constant.  It has changed
in type (to a polycarbonate dielectric) to reduce electrical leakage that
could result in the VOX relay circuit staying activated.  If replacing this
component, recommend replacing with the 0.068-uF polycarbonate dielectric.

Straight from Uncle's mouth!  :)

Ian, K6SDE

-----Original Message-----
From: collins-bounces at mailman.qth.net
[mailto:collins-bounces at mailman.qth.net] On Behalf Of Paul
Sent: Thursday, November 29, 2007 6:23 PM
To: collins at mailman.qth.net
Subject: RE:[Collins] KWM2a, C47

  Cam,
   
  First, according to my manual C47 is a 0.047uf 400vdc paper dieletric
  cap, not a 0.47uf, so if your rmanual says 0.47uf it is most likely a
  typo
  .
  Second,C47 with a value of 0.047uf was added as an additional C47, in
  parallel with the original C47, which is a 0.01uf at 400 vdc. This
  occurred as part of Collins KWM2/2A service bulletin number 2 (SB2) to
  alter the VOX delay time constant. This brought the capacitance up to
  0.057uf. In later versions of the KWM2/2A the orginal C47 or C47
  combination for SB2, became a single 0.068uf plastic diel. cap at 400 vdc.
   
  What is it you are trying to accomplish? Replace a bad cap, restore a
  circuit that is missing a cap, change the time constant of the vox
  delay? You should be able to use any current mylar cap in that location,
  yes, an orange drop should do fine. If there are already two caps in
  your circuit, a 0.047uf and a 0.01uf, and you're going to be in there
  anyway, you could remove both and replace with a single 0.068uf. All these
caps are readily available.
   
  Good luck
   
  Paul W2EC
______________________________________________________________