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#uBITX polyfuse?

#ubitx

Keith VE7GDH All Messages By This Member #46225 Anyone using polyfuses with a uBITX instead of a fuse? I have some here, but have never played with them before. Would they react quick enough to provide any real protection, or would they be just too slow? -- 73 Keith VE7GDH
K9HZ All Messages By This Member #46236 Depends what you are trying to protect... It's as good as a slo blow fuse. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook! Moderator – North American QRO Group at Groups.IO. email: bill@... toggle quoted message Show quoted text -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Keith VE7GDH Sent: Tuesday, April 10, 2018 3:28 PM To: [email protected] Subject: [BITX20] #uBITX polyfuse? Anyone using polyfuses with a uBITX instead of a fuse? I have some here, but have never played with them before. Would they react quick enough to provide any real protection, or would they be just too slow? -- 73 Keith VE7GDH --- This email has been checked for viruses by AVG.
Doug W All Messages By This Member #46237 If you access the list from?/g/BITX20/topics there is a search function.? Here's the last discussion?/g/BITX20/topic/7489182 regarding polyfuses and other things.
lostfrogsrecords #46244 Yep! They work slowly, need a current limiting resistor to allow the polyfuse to reach cutoff temperature before the protected device fails.? Again, slow... Ki4PSR toggle quoted message Show quoted text On 4/10/2018 6:29 PM, K9HZ wrote: Depends what you are trying to protect... It's as good as a slo blow fuse. Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois Owner – Operator Villa Grand Piton – J68HZ Soufriere, St. Lucia W.I. Rent it: www.VillaGrandPiton.com Like us on Facebook! Moderator – North American QRO Group at Groups.IO. email: bill@... -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Keith VE7GDH Sent: Tuesday, April 10, 2018 3:28 PM To: [email protected] Subject: [BITX20] #uBITX polyfuse? Anyone using polyfuses with a uBITX instead of a fuse? I have some here, but have never played with them before. Would they react quick enough to provide any real protection, or would they be just too slow? -- 73 Keith VE7GDH --- This email has been checked for viruses by AVG.
Jerry Gaffke All Messages By This Member #46247 As a means of protecting the IRF510's, I think a polyswitch in the PA-PWR line should work great. The IRF510's mostly fail due to overheating, a small polyswitch will have far less thermal mass then the IRF510's plus heatsinks. Often an LED and resistor in series are placed across the polyswitch, such that when the polyswitch opens up the LED turns on. That tells the operator to shut down power and let the polyswitch reset. Would be interesting to experiment a bit, the IRF510's are cheap. Turn up the gate bias pot till something gives. My bets are on the polyswitch (rated for say 2 or 3A, will blow somewhat north of that). I doubt you need a limiting resistor in this particular case.? Jerry toggle quoted message Show quoted text On Tue, Apr 10, 2018 at 07:38 pm, lostfrogsrecords wrote: They work slowly, need a current limiting resistor to allow the polyfuse to reach cutoff temperature before the protected device fails.? Again, slow...
K9HZ All Messages By This Member #46260 开云体育 Depends upon the mode of failure i suppose. ?My protection circuit posted on acts far quicker than a polyfuse could and is more certain to protect in any case. ? Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch – K9ZC Staunton, Illinois ? Owner – Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it: email:??bill@... ? toggle quoted message Show quoted text On Apr 10, 2018, at 10:11 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: As a means of protecting the IRF510's, I think a polyswitch in the PA-PWR line should work great. The IRF510's mostly fail due to overheating, a small polyswitch will have far less thermal mass then the IRF510's plus heatsinks. Often an LED and resistor in series are placed across the polyswitch, such that when the polyswitch opens up the LED turns on. That tells the operator to shut down power and let the polyswitch reset. Would be interesting to experiment a bit, the IRF510's are cheap. Turn up the gate bias pot till something gives. My bets are on the polyswitch (rated for say 2 or 3A, will blow somewhat north of that). I doubt you need a limiting resistor in this particular case.? Jerry On Tue, Apr 10, 2018 at 07:38 pm, lostfrogsrecords wrote: They work slowly, need a current limiting resistor to allow the polyfuse to reach cutoff temperature before the protected device fails.? Again, slow...

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