NB: this posting is about an Elecraft radio ;-)
* * * I was thinking about doing two things to my vereable K2 #0771, as I wait for new Elecraft toys: ... one is to re-jigger the divider resistors to offset the K2 voltmeter so it reads what my actual input-port voltage is, rather than the "internal" voltage and ...two was changing the TO-220 regulator(s) to some kind of precision type ... could not remember if it was the 8V LVDO or the plain-old 7805 type that set the reference voltage for other measurements. Wasn't obvious from the schematic, at first. On the matter of the offset, I suppose that the voltmeter's ultimate accuracy will be reduced a bit because a fixed offset won't compensate for the actual, varying drop through the polarity-protect diode, as that will vary over the IsubF ... however, I've switched mine to the newer Schottky type -- and aren't they V-drop-flatter over the current curve than the original? And on the second matter of the regulator precision, maybe I am mistaken about the availability of more-accurate TO-220 parts. What is the typical load that the 8V rail has? I'm guessing a 1 amp regulator will suffice. Which regulator was the "critical" voltage unit? It was the +5v, right? Steve KZ1X/4 ____________________________________________________ Start your day with Yahoo! - make it your home page http://www.yahoo.com/r/hs _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com