5R4 and 5U4 solid state replacement on an Apache or Marauder

[Patrick]

Thanks, great input....... Pat
  ----- Original Message ----- 
  From: G3OOU at aol.com 
  To: brookbank at TRIAD.RR.COM ; HEATH at LISTS.TEMPE.GOV 
  Sent: Monday, May 25, 2009 6:12 PM
  Subject: Re: 5R4 and 5U4 solid state replacement on an Apache or Marauder


  Hi Pat

  I would check the ratings of the electrolytic caps as you are going to get a higher inrush current when you switch on. Although the directly heated rectifiers warm up fairly quickly (2-3 seconds) they do provide some limit to the switch on surge whereas the semiconductor diodes will charge the capacitors instantly and the only significant current limit is the inherent resistance in the main transformer.

  With no load, the voltage on the smoothing caps will be 1.414 times the AC supplied to the diodes. Otherwise it should be fine and you will benefit from the reduced amount of heat.

  73

  Bob 
  G3OOU
  G-QRP 6907
  Joint site with Crystal Palace Radio & Electronics Club: www.g3oou.co.uk
  My technical site: http://www.qsl.net/g3oou/


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