0.7 V for a regular diode. I believe Elecraft uses Schottky diodes for protection because of their lower voltage drop (0.15 to 0.45 V).
wunder K6WRU Walter Underwood CM87wj http://observer.wunderwood.org/ (my blog) > On Feb 26, 2019, at 11:20 AM, Harlan Sherriff via Elecraft > <elecraft@mailman.qth.net> wrote: > > Diode voltage drop is approximately 0.7v per diode > > Sent from my iPhone > >> On Feb 26, 2019, at 2:16 PM, Jack Brindle via Elecraft >> <elecraft@mailman.qth.net> wrote: >> >> Be sure to use a DVM external to the K3 to measure the voltage at the K3. >> The input protection diode in the K3 will cause some drop (1/4 to 1/2 volt >> perhaps). What this means is that the K3 meter will always show less voltage >> than is really present at the transceiver supply input. >> >> >> 73! >> Jack, W6FB >> >>> On Feb 26, 2019, at 9:37 AM, mjpilgrim <mpilg...@bellsouth.net> wrote: >>> >>> Well, i have received many helpful replies both publicly here and in private >>> emails. Thanks to all for those ideas brought forward. >>> >>> What I've gleaned to be most useful from your responses has been the >>> suggestions to investigate the power cord with power poles connecting the K3 >>> to my switching power supply. Per those inputs I've fabricated a shorter >>> (5') cable and insured that I used the crimp terminals rated at 30 AMPS. >>> The initial result has been a reduction of about 30% of my measured voltage >>> drop (now 13.6 Volts in standby to 12.5V when key down 100W CW........ >>> previously the drop was to 12.0)............... Some background info. is >>> that the original observation of a voltage drop occurred as the K3 was >>> connected to my minimal-sized Solar Power supply. After extensive >>> investigation, additional hardening in the wiring, and replacement of a >>> suspect imported power distribution strip, I was convinced there was no >>> voltage drop evidenced there. The battery voltage measured at the input to >>> the referenced DC power distribution strip did not waver under key down >>> tests with the attached K3............. There remained however, the >>> above-mentioned voltage drop displayed in the K3 metering. >>> >>> i plan to rebuild the afore-mentioned 5' power cable, this time soldering >>> the power pole lugs rather than trusting crimped connections. My suspicion >>> that the power cable is suspect, so i plan to address those curiosities >>> before moving on to other possible cause. >>> >>> Thanks again for your continued ideas and suggestions. >>> Regards, >>> Mike, K5MP >>> >>> >>> >>> -- >>> Sent from: http://elecraft.365791.n2.nabble.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 >> >> ______________________________________________________________ >> 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 > > ______________________________________________________________ > 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 ______________________________________________________________ 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
