[Heathkit] DX-40 Keying trouble

[Robert Nickels]

  On 8/30/2010 3:51 PM, Glen Zook wrote:
> It showed less than 0.2 ohms to ground from the B+ line
Some build runs of the National HRO-500 are notorious for disk ceramic 
failures, and the maximum DC voltage in this receiver  is 12 volts!   
The root cause of the problem is silver migration, which remains an 
issue even today for manufacturers of multilayer ceramic capacitors, 
membrane switches, and other devices.  Thankfully, with proper material 
selection and process control we don't have to deal with this problem as 
often as others.

My experience confirms that even a .1uf bypass on a 10 volt line can 
develop an sub-ohmic short - after all it is silver!

73, Bob W9RAN