BE-5 - what do the controls on the BE-5 do? Selenium rectifier voltage drop

[Ed Tanton]

What I have done about seleniums on several small units (B&W 380-B T/R
Switches for example) was to measure the voltage on output side of the
selenium, then the current. I then replaced the selenium with a 1N4007 or
equiv. silicon diode. Next, briefly turning it on allows measurement of the
new output voltage. Since you now know how many volts you need to drop at
however many milliamps, you can not only calculate the value of resistor you
need as well as the required power rating. Works like a champ. 

Do not disregard the voltage rating of the electrolytics during the 2nd
part. Probably wouldn't hurt to replace them when you do this anyway. Note
that if you do, and if you increase the capacitances much at all, the DC
voltage is likely to rise-so these measurements should be taken after any
such replacement and before the selenium replacement. Personally, I would
raise the voltage ratings of the electrolytics, but try and stay close to
the capacitance values.


73  Ed Tanton N4XY <n4xy at earthlink.net> 
 
website: http://www.n4xy.com  
 
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