Re: [Elecraft] KPA500 Parts
7.5V It is not there to regulate, but to limit in case of something bad happening, while allowing the gate of the FET to get the full control voltage for T/R switching. The zener normally is not conducting. 73, Lyle KK7P On Wed, Aug 17, 2022 at 12:08 PM RALPH TURK wrote: > The real question is/was what value of zener. > > > On 08/17/2022 9:45 AM Andy Durbin wrote: > > > > > > "The latest revision of the schematic for the KPA500 TR Switch shows a > Zener diode at the gate of Q4 in place of R3, the 100K resistor previously." > > > > What is the latest revision? I have Rev D which is later than any I > have found on-line but it shows R3 not a Zener. > > > > Andy, k3wyc > > __ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to w7...@comcast.net > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to kk7p4...@gmail.com > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] KPA500 Parts
The real question is/was what value of zener. > On 08/17/2022 9:45 AM Andy Durbin wrote: > > > "The latest revision of the schematic for the KPA500 TR Switch shows a Zener > diode at the gate of Q4 in place of R3, the 100K resistor previously." > > What is the latest revision? I have Rev D which is later than any I have > found on-line but it shows R3 not a Zener. > > Andy, k3wyc > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to w7...@comcast.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] KPA500 Parts
"The latest revision of the schematic for the KPA500 TR Switch shows a Zener diode at the gate of Q4 in place of R3, the 100K resistor previously." What is the latest revision? I have Rev D which is later than any I have found on-line but it shows R3 not a Zener. Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] KPA500 Parts
The latest revision of the schematic for the KPA500 TR Switch shows a Zener diode at the gate of Q4 in place of R3, the 100K resistor previously. Its obviously for gate protection. There are no markings on the schematic what this diode is although the spec sheet for the IRFSL9N60APBE does say the gate-source threshold is maximum of 4V. Anyone know what the value of this thing is before I just stuff in a 4v Zener? Dr. William J. Schmidt - K9HZ J68HZ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
