Jack: A diode is a good idea and sound engineering practice. However if you look at the FET schematic from the manufacture's data sheet carefully you will see that the FET has a built in diode. That's why they make such good relay drivers. 73 Fred, AE6QL
-----Original Message----- From: Elecraft [mailto:[email protected]] On Behalf Of Jack Brindle Sent: Monday, September 7, 2015 7:49 PM To: Jim Miller Cc: Elecraft Reflector Subject: Re: [Elecraft] K3 Keyout? If it were _my_ K3 (or K3S), I would add the very inexpensive 1N5400 or 1N5407 diode across the relays and eliminate the worry. Even reed relays can produce quite a kick, and the low cost of the diode would do wonders for peace of mind. This same advice goes for antenna (and other) relays switched by the KRC2. Jack Brindle, W6FB > On Sep 7, 2015, at 5:40 PM, Jim Miller <[email protected]> wrote: > > Thanks all. The 200v tolerance will handle the minimal energy produced > by the reed relay field collapsing. > > 73 > > jim ab3cv > > > > On Mon, Sep 7, 2015 at 8:32 PM, Don Wilhelm <[email protected]> wrote: > >> Why do you need to look at the schematic. The K3S specification says >> it will handle +200 volts at 5 Amps, so those are the limits at the box level. >> No matter what the device data sheet for a device might indicate, >> there can be other considerations in the K3S design (or other >> 'boxes') that say you should observe the specifications for the >> entire unit rather than trying to re-engineer from the device specifications. >> >> 73, >> Don W3FPR >> >> >> On 9/7/2015 7:59 PM, Jim Miller wrote: >> >>> I don't have schematics for my K3S but going by those for the K3. >>> The KeyOut line (RCA Jack) is driven by a IRF1630 which appears to >>> be out of production. Either than or it is a misprint and is actually a IRF630. >>> >>> If the latter it appears pretty burly. Can I assume it can drive a >>> pair of reed relays without suffering an inductive kick failure? >>> >>> >>> >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
