Hi, Harold - well it's been a while, I know that we regularly used line bypasses in electricity meter and they had to be really robust, but I was mostly and RF and communications guy and when I had to fool with power supply designs for the meters, I generally just copied whatever was done before. Of course out there on the line side of the meter is a hellish surge environment. On guy mentioned film capacitors, but I would be a bit skeptical of those as RF bypasses. The capacitors that we used were very robust, as they had to withstand 480 volt high-line voltage or 530 VAC. And yes I have seen my share of fried line bypass capacitors in consumer electronics and radio gear.
73, Charlie, K4OTV -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of HAROLD SMITH JR Sent: Wednesday, February 04, 2015 9:16 PM To: Charlie Cunningham; 'Paul Christensen'; topband@contesting.com Subject: Re: Topband: AC line bypass capacitors Hi Charlie, I can remember when the Collins S-Line used .01 600volt disk ceramic capacitors on the power supply connector. They were from the AC switch to ground. They were almost always burnt and many times only the leads left. 73 Price W0RI On Wednesday, February 4, 2015 6:31 PM, Charlie Cunningham <charlie-cunning...@nc.rr.com> wrote: Hi, Paul For AC line bypass capacitors look for UL-rated Ceramic Disc capacitors that typically have AC working voltages like 250 VAC or higher. These are designed and rated for AC line service and can take the surges that occur on AC lines. Check Digi-Key, Newark and others - you'll find plenty! 73, Charlie, K4OTV -----Original Message----- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Paul Christensen Sent: Wednesday, February 04, 2015 3:55 PM To: topband@contesting.com Subject: Re: Topband: AC line bypass capacitors > >My 160 TX is causing RFI to one of my baseboard heater programmable >thermostats (switches modes, temperature, when I transmit). The >thermostat has a 2 wire connection to 240VAC in a metal receptacle box >that has a third wire common ground wire. I would like to try >bypassing the AC line. > Can someone suggest an appropriate (safe) capacitor for this purpose, >e.g. > a Digi-Key or Mouser part number? Should I use one capacitor across >the 240VAC or two capacitors, one from each 120VAC line to the common wire? > Thanks for the help. > _________________ As a substitute for X1 Y2 line caps, an in-line RFI/EMI filter can be used that already contains the X/Y-rated caps. See the bottom of p. 21: http://audiosystemsgroup.com/RFI-Ham.pdf These filters can often be cannibalized from old PC power supplies and discarded industrial equipment. Paul, W9AC _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband