A quick look at the circuit diagram shows that buttons are taken from a potential divider to CD74HC4051M inputs. These switches (unless I've misread the diagram) will therefore take the input current of the multiplexer which is typically <1uA. I don't know the spec for the Elecraft switch but a similar one requires a minimum current of 10uA. This should be checked more rigorously, but it might indicate a potential problem.
David G3UNA Subject: Re: [Elecraft] K3 Check Your Buttons Paul, I am very surprised that this has not come up before! My K3 is #570 and it has had 4 front panel boards (a couple for what I called flaky or just bad switches and the rest for other reasons) and the same problem you describe is still there. The latest one is the best, but I still get some strange things happening - mostly with the BAND and MODE switches, but it has occurred occasionally with other switches, and it is not very reproducible - it can be very intermittent, or it can happen fairly often. When the K3 went back to Elecraft the beginning of the year for a different problem they checked out the Front Panel switches and said the switch operation is fine, but it's not. I have seen the problem on a fairly new K3 owned by a ham near here .... I have seen the problem on the K3s at the Elecraft booth at Hamcom. Again, it is intermittent. For the longest time I figured it was me and the way I press the buttons on #570 .... I did try SW test and Sca Adc - at times the beeps were slow, unevenly spaced or did not appear at all and it did not seem to me that the switches with flickering scan codes were the switches that were causing mis-operations. But when I press and hold the ALT to switch sidebands, and the radio changes three modes, maybe a band, reverses sideband and turns on the RX ANT, it causes one to wonder .... but K3support does not have any of these problems! So I have decided that the K3 switches are a trade-off to have the best receiver that is out there in the Amateur market. And so are the several other operational quirks, but again I can put up with those when and if they come up to the top of the "upcoming K3 features" list. Like you, I'm out of warranty, so $400 is out of the question for yet another Front Panel board. Besides, I don't think it can be fixed. 73 Hank K8DD ______________________________________________________________ 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
