[Elecraft] Suspicious power supply

Tue Mar 30 14:58:01 2004

Hi

Some voltmeters have a high low function where you can connect the meter =
to the power supply and then come back and read the upper and lower =
voltage recorded on the meter. Most Fluke meters will do this as well as =
many others. You should do this with the power supply under load for a =
good test.

Don Brown
KD5NDB
  ----- Original Message -----=20
  From: Martin<mailto:[email protected]>=20
  To: [email protected]<mailto:[email protected]>=20
  Sent: Tuesday, March 30, 2004 1:46 PM
  Subject: [Elecraft] Suspicious power supply

  Hello elecrafters,
  today my K2 showed a strange behavior.
  About 1 minute after switching it on, it suddenly lost power for
  fractions of a second, then came alive again.
  Then, after 2 mins. it happened again. And again after a couple of
  mins.

  I tried to reproduce the failure by tapping and knocking on the case,
  i shaked the radio and the power cord - nothing happened.

  The radio ran flawlessly for 30 mins, then i shut it off .

  I switched to the internal battery and left the radio on for 2
  hours with the display set to show voltage & current.
  When i returned to the shack, the display still showed voltage &
  current.
  Next test was running the radio with a different power supply, again
  with display set to show Voltage & current.
  After 4 hours it still showed v & c.
  If there had been a failure in the meantime, the display would have =
shown the
  frequency as it always does when power is back. Right?

  If there is something wrong with the radio it should also fail when
  battery-powered or with the second power supply. Right?

  So the culprit must be the first power supply.
  Either the voltage is below or in excess of a certain level for a few
  ten milliseconds. Right?

  Any ideas on how to monitor the power supply without staring on a
  voltmeter all day? I have no scope.
  The supply is a switcher.

  Any comments welcome.

  --=20
  Best regards,
   Martin
  K2 #2706                          =
mailto:[email protected]<mailto:[email protected]>

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