[Drakelist] Replacement caps for the PS7
Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
Well, I hope since you asked this, it will bring on one of the guru's that will explain ripple current. I have been seeing that lately, and this old guy will admit to not knowing what the heck it is I wouldn't think you would need the same rating as the power supply current though What say experts??? I'm wanting to change out my PS7 caps too. 73, Don, WB5HAK - Original Message - From: Ron wd8...@yahoo.com To: drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:34 PM Subject: [Drakelist] Replacement caps for the PS7 Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
I changed out the caps in my PS-7 a couple of years back and used caps from Mouser. Not sure why you're concerned about current rating - that's not a factor. I think you'll find the caps rated only by voltage and capacitance - oh yes, and by temperature max. In the PS-7, you ought to worry more about the physical characteristics. It's nice if you can find caps of the same diameter so you don't have to change the mounting hardware. Also, the post height for the terminals is a factor. I can't remember now whether the original caps had the longer posts or whether or not I ordered the right height. Before ordering, take everything off of one of the terminals and measure the height. My caps have been running several hours per day for a couple of years with no problems. I may be able to dig out a receipt if you have problems locating a replacement. 73, Floyd - K8AC - Original Message - From: Don Cunningham wb5...@martineer.net To: Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 9:42 PM Subject: Re: [Drakelist] Replacement caps for the PS7 Well, I hope since you asked this, it will bring on one of the guru's that will explain ripple current. I have been seeing that lately, and this old guy will admit to not knowing what the heck it is I wouldn't think you would need the same rating as the power supply current though What say experts??? I'm wanting to change out my PS7 caps too. 73, Don, WB5HAK - Original Message - From: Ron wd8...@yahoo.com To: drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:34 PM Subject: [Drakelist] Replacement caps for the PS7 Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
Thanks, Floyd. I do see caps now rated with ripple current current and didn't know what it meant. Still don't, but if you feel it's unimportant, I'll not worry about it, hi. 73, Don, WB5HAK - Original Message - From: K8AC k...@k8ac.net To: Don Cunningham wb5...@martineer.net; Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:53 PM Subject: Re: [Drakelist] Replacement caps for the PS7 I changed out the caps in my PS-7 a couple of years back and used caps from Mouser. Not sure why you're concerned about current rating - that's not a factor. I think you'll find the caps rated only by voltage and capacitance - oh yes, and by temperature max. In the PS-7, you ought to worry more about the physical characteristics. It's nice if you can find caps of the same diameter so you don't have to change the mounting hardware. Also, the post height for the terminals is a factor. I can't remember now whether the original caps had the longer posts or whether or not I ordered the right height. Before ordering, take everything off of one of the terminals and measure the height. My caps have been running several hours per day for a couple of years with no problems. I may be able to dig out a receipt if you have problems locating a replacement. 73, Floyd - K8AC - Original Message - From: Don Cunningham wb5...@martineer.net To: Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 9:42 PM Subject: Re: [Drakelist] Replacement caps for the PS7 Well, I hope since you asked this, it will bring on one of the guru's that will explain ripple current. I have been seeing that lately, and this old guy will admit to not knowing what the heck it is I wouldn't think you would need the same rating as the power supply current though What say experts??? I'm wanting to change out my PS7 caps too. 73, Don, WB5HAK - Original Message - From: Ron wd8...@yahoo.com To: drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:34 PM Subject: [Drakelist] Replacement caps for the PS7 Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
Maybe this might help: http://www.newark.com/pdfs/techarticles/kemet/Ripple-Current-Capabilities-Technical-Update.pdf Chuck Don Cunningham wrote: Thanks, Floyd. I do see caps now rated with ripple current current and didn't know what it meant. Still don't, but if you feel it's unimportant, I'll not worry about it, hi. 73, Don, WB5HAK - Original Message - From: K8AC k...@k8ac.net To: Don Cunningham wb5...@martineer.net; Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:53 PM Subject: Re: [Drakelist] Replacement caps for the PS7 I changed out the caps in my PS-7 a couple of years back and used caps from Mouser. Not sure why you're concerned about current rating - that's not a factor. I think you'll find the caps rated only by voltage and capacitance - oh yes, and by temperature max. In the PS-7, you ought to worry more about the physical characteristics. It's nice if you can find caps of the same diameter so you don't have to change the mounting hardware. Also, the post height for the terminals is a factor. I can't remember now whether the original caps had the longer posts or whether or not I ordered the right height. Before ordering, take everything off of one of the terminals and measure the height. My caps have been running several hours per day for a couple of years with no problems. I may be able to dig out a receipt if you have problems locating a replacement. 73, Floyd - K8AC - Original Message - From: Don Cunningham wb5...@martineer.net To: Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 9:42 PM Subject: Re: [Drakelist] Replacement caps for the PS7 Well, I hope since you asked this, it will bring on one of the guru's that will explain ripple current. I have been seeing that lately, and this old guy will admit to not knowing what the heck it is I wouldn't think you would need the same rating as the power supply current though What say experts??? I'm wanting to change out my PS7 caps too. 73, Don, WB5HAK - Original Message - From: Ron wd8...@yahoo.com To: drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:34 PM Subject: [Drakelist] Replacement caps for the PS7 Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
I'm old school also. WVDC rating and capacity--but with the newer, and very compact construction of caps, this ripple current rating can be important. I get that it is the rating the cap will handle passing the AC ripple component to ground. Remember that there is an AC component on the 13.8VDC line (ripple) the cap will pass that AC to ground thus it is passing AC current. The current is the RMS ripple value divded by the Impedance of the cap at the ripple frequency. That being said, I have replaced ALOT of PS filter caps in 40 Years of teching and have never worried about it. Pick a cap with same size for mounting, and better than original temp rating and forget about it. Just my understanding and .02 Curt KU8L K8AC wrote: I changed out the caps in my PS-7 a couple of years back and used caps from Mouser. Not sure why you're concerned about current rating - that's not a factor. I think you'll find the caps rated only by voltage and capacitance - oh yes, and by temperature max. In the PS-7, you ought to worry more about the physical characteristics. It's nice if you can find caps of the same diameter so you don't have to change the mounting hardware. Also, the post height for the terminals is a factor. I can't remember now whether the original caps had the longer posts or whether or not I ordered the right height. Before ordering, take everything off of one of the terminals and measure the height. My caps have been running several hours per day for a couple of years with no problems. I may be able to dig out a receipt if you have problems locating a replacement. 73, Floyd - K8AC - Original Message - From: Don Cunningham wb5...@martineer.net To: Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 9:42 PM Subject: Re: [Drakelist] Replacement caps for the PS7 Well, I hope since you asked this, it will bring on one of the guru's that will explain ripple current. I have been seeing that lately, and this old guy will admit to not knowing what the heck it is I wouldn't think you would need the same rating as the power supply current though What say experts??? I'm wanting to change out my PS7 caps too. 73, Don, WB5HAK - Original Message - From: Ron wd8...@yahoo.com To: drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:34 PM Subject: [Drakelist] Replacement caps for the PS7 Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
Ron - Ripple current is a relatively new specification for electrolytic capacitors, which today see much higher frequency ripple typical of DC/DC converters (aka switching power supplies,). The result is that that newer caps designed to have extremely low ESR, and so large ripple currents are typical. The heat generated by the current flowing through that low resistance is a major determining factor of capacitor life. There are calculations to determine the various contributors to capacitor heating in a given scenario, but... From a practical standpoint, the RMS value of the ripple is 0.707 X the peak AC voltage squared divided by the ESR of the capacitor. Bottom line... Pick capacitors that are a physical match to the ones in the PS-7, rated at 105 degrees C if possible, and forget them for another 30 years. 73, Garey - K4OAH St Charles, IL Drake 2-B, 4B C-Line, TR-4/C Service Supplement CDs www.k4oah.com Ron wrote: Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Replacement caps for the PS7
You are correct, Curt. Where it becomes very important is in large 3 phase rectifier systems such as are used in PWM. variable frequency drives--particularly in medium voltage (4160V) and medium (500HP) and large (10,000HP) motors. The prepackaged smoke can get out if things aren't matched well! Chuck Curt Nixon wrote: I'm old school also. WVDC rating and capacity--but with the newer, and very compact construction of caps, this ripple current rating can be important. I get that it is the rating the cap will handle passing the AC ripple component to ground. Remember that there is an AC component on the 13.8VDC line (ripple) the cap will pass that AC to ground thus it is passing AC current. The current is the RMS ripple value divded by the Impedance of the cap at the ripple frequency. That being said, I have replaced ALOT of PS filter caps in 40 Years of teching and have never worried about it. Pick a cap with same size for mounting, and better than original temp rating and forget about it. Just my understanding and .02 Curt KU8L K8AC wrote: I changed out the caps in my PS-7 a couple of years back and used caps from Mouser. Not sure why you're concerned about current rating - that's not a factor. I think you'll find the caps rated only by voltage and capacitance - oh yes, and by temperature max. In the PS-7, you ought to worry more about the physical characteristics. It's nice if you can find caps of the same diameter so you don't have to change the mounting hardware. Also, the post height for the terminals is a factor. I can't remember now whether the original caps had the longer posts or whether or not I ordered the right height. Before ordering, take everything off of one of the terminals and measure the height. My caps have been running several hours per day for a couple of years with no problems. I may be able to dig out a receipt if you have problems locating a replacement. 73, Floyd - K8AC - Original Message - From: Don Cunningham wb5...@martineer.net To: Ron wd8...@yahoo.com; drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 9:42 PM Subject: Re: [Drakelist] Replacement caps for the PS7 Well, I hope since you asked this, it will bring on one of the guru's that will explain ripple current. I have been seeing that lately, and this old guy will admit to not knowing what the heck it is I wouldn't think you would need the same rating as the power supply current though What say experts??? I'm wanting to change out my PS7 caps too. 73, Don, WB5HAK - Original Message - From: Ron wd8...@yahoo.com To: drakelist@zerobeat.net Sent: Wednesday, October 28, 2009 8:34 PM Subject: [Drakelist] Replacement caps for the PS7 Okay before everyone says Heathkit shop like they did last time, note that the PS7 is the 13.8 volt power supply for the TR7 not the L7 power supply. I need new filter caps, any thoughts on where and which ones? I spotted some on mouser, but I can not find their ripple current ratings. Apparently Mallory has changed numbers slightly and all I can do is guess given the size above and below that they are about the correct current rating. On that subject, I presume the ones in the supply are at least 12 amps each. That would get them close for the 25 Amp constant current that the supply is suppose to be able to run. With the fan cooling them, I would think 12 amp caps would be about right. TNX es 73, Ron WD8SBB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.698 / Virus Database: 270.14.37/2466 - Release Date: 10/28/09 14:39:00 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
