Mic Problem?
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Murphy's law struck down K2 #4913 today. :-(
I was taking pre-net checkins for the Central States Traffic Net (7.253.5) when I started getting reports as if I had a bad antenna connection. Things got worse from there. I started getting reports that my audio was very garbled. Then the K2 wouldn't return to normal recieve after transmitting. If I hit the mode button or cycled through the XFIL selections, it would return to normal. (When it messed up like this, the rx audio sounded very tinny). Then it wouldn't transmit at all. Did a full reset - no help. I checked my mic on another rig (Alinco DR-610T) and it works fine there. Help! 73 de Ken KGØWX - Flying Pigs #-1055 Elecraft K2 #4913 - Kadiddlehoppers #11,808 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Ken -
Something similar happened to me when I was building my K2. In my case, it was a bad PROM chip on the DSP unit. You didn't say whether or not you have the DSP installed, but I suspect the same sort of problem could occur with other modules. In my case, as I cycled through the filter and mode settings, the K2 would act almost normal for one turn through the options, and really weird the next time around. The tinny audio and intermittently garbled audio were some of the symptoms my unit exhibited before changing the chip. In my case, since the bad part was on the DSP module, removing the module and jumpering the connections restored the rig to normal operation. That may be something you can check, removing an option module and temporarily bypassing it's function, that is, to see what happens. Possible things to check: Did you make sure every pin is soldered properly on the PROM chips, wherever they appear? Maybe that's a clue, maybe not. I am sure others will have additional information. Good luck! - Jim, KL7CC Ken Bessler wrote: >Murphy's law struck down K2 #4913 today. :-( > >I was taking pre-net checkins for the Central States >Traffic Net (7.253.5) when I started getting reports >as if I had a bad antenna connection. Things got worse >from there. > > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Ken Bessler
Ken,
That sounds like something did not get properly soldered, but was making marginal contact until now. Look for it on the KSB2 board and/or its connectors to the RF board for the most likely place. You may want to just reflow the solder joints in case there is one that moved on you while it was cooling - such cold solder joints are often difficult to spot visually. As a second thought, what kind of antenna are you using? If you are experiencing 'RF in the shack', that can cause a myriad of strange things to happen. 73, Don W3FPR > -----Original Message----- > > Murphy's law struck down K2 #4913 today. :-( > > I was taking pre-net checkins for the Central States > Traffic Net (7.253.5) when I started getting reports > as if I had a bad antenna connection. Things got worse > from there. I started getting reports that my audio was > very garbled. Then the K2 wouldn't return to normal > recieve after transmitting. If I hit the mode button or > cycled through the XFIL selections, it would return to > normal. (When it messed up like this, the rx audio > sounded very tinny). Then it wouldn't transmit at all. > > Did a full reset - no help. > > I checked my mic on another rig (Alinco DR-610T) and > it works fine there. > > Help! > > 73 de Ken KGØWX - Flying Pigs #-1055 > Elecraft K2 #4913 - Kadiddlehoppers #11,808 > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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Don, Scott - et all -
Thanks for the help - after doing a full reset & re- alignment then disassembling the radio to check for GND @ mic socket pins 7&8 (ok), I re-assembled K2 #4913 and focused on the mic again. I had ASSumed the mic was OK because it worked FB in my Alinco 2m/440 mobile. Well...... After checking the mic again, I found the ground braid was bad. I cut 2" off the plug end of the cord and re-wired the plug. Works! I looked for a fault in the old cord end and found the braid was tattered & broken right where the clamp was. Thanks again for the help! 73 de Ken KGØWX - Flying Pigs #-1055 Elecraft K2 #4913 - Kadiddlehoppers #11,808 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Don Wilhelm-3
Reminds me of when I was a repair tech and a guy brought in his *cough*
Swan *cough* and he had swapped the shield and hot. Let me tell you, that doesn't make the microphone work any better. On Thu, 27 Oct 2005, Ken Bessler wrote: > Don, Scott - et all - > > Thanks for the help - after doing a full reset & re- > alignment then disassembling the radio to check > for GND @ mic socket pins 7&8 (ok), I re-assembled > K2 #4913 and focused on the mic again. > > I had ASSumed the mic was OK because it worked > FB in my Alinco 2m/440 mobile. Well...... > > After checking the mic again, I found the ground > braid was bad. I cut 2" off the plug end of the cord > and re-wired the plug. Works! > > I looked for a fault in the old cord end and found the > braid was tattered & broken right where the clamp was. > > Thanks again for the help! > > 73 de Ken KGØWX - Flying Pigs #-1055 > Elecraft K2 #4913 - Kadiddlehoppers #11,808 > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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 > Hisashi T Fujinaka - [hidden email] BSEE(6/86) + BSChem(3/95) + BAEnglish(8/95) + MSCS(8/03) + $2.50 = latte _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Ken Bessler
Ken,
Wow, a quick perusal of your connections sounds like you may have ground loop potentials galore in that hookup. I will digest your notes better in the morning, but at a minimum, yes, you should ground the mic jack. The directions for grounding the mic jack are around the web somewhere (might check the Elecraft website), but it is really easy - remove the front panel and then extract the front panel board (remove knobs, encoder nut and the screw next to the encoder). When you have the mic connector sitting 'bare' on the front panel board, wrap a wire around the mic jack and solder that wire to the jack (takes a LOT of heat), then ground that wire to the nearby grounding point on the PC board. If you want to (or need to) do an even better job of it, also run a short piece of braid from the ground point/mic jack wire to the chassis 2-D connector and pinch the wire against the chassis when the front panel is assembled to provide a direct path for any common mode currents on the mic cable shield direct to the chassis of the K2 rather than relying on a circuitous path through the PC board somewhere to the chassis (this is referred to in audio circles as the "pin 1 problem" - I give Jim Brown credit for that one). Try grounding the mic jack - it may not cure everything, but it certainly will do no harm. One other thing - be certain you have not connected the PC serial port pin 1 to the shield at the computer end of the K2 to PC cable. Pin 1 at the PC end is Data Carrier Detect, and pin 1 at the K2 end is chassis ground - the two do not match. The computer chassis ground is the shell of the DB9 connector, not pin 1. The recent discussion of this 'RS232' situation under the subject of the 'microHam keyer' interface may be relevant in your case. 73, Don W3FPR -------Original Message------- Thanks, Don - I did some tests with the help of KB0OMQ/M this evening and discovered several things: 1) No matter what I do, I cannot get the PTT with one glaring exception - it works FB if I hook up my PC! 2) VOX works, provided I hit the PTT to switch in the mic element. 3) The transmitted audio sounds better either at 5w or less *or* when on my R7000 vertical. My other antenna is a coax/choke/ladder line fed 40m inverted V @ 40' The computer PTT is very simple - COM 2 is the radio and COM 1 goes to a 1 transistor PTT to ground switch. The output of this switch, along with the audio lines, go to a mic connector with a pigtail going to the speaker jack. Pretty standard stuff but it is an entirely seperate PTT control than the mic. I just did a test - I opened the mic up and used a test lead to bypass the ground from the PTT switch to the mic connector. Nothing. Then I had an idea - I tried the same trick but used the shell of the *computer* mic plug with that *unhooked* from the radio. It worked! I then tried touching the bypass lead to a case screw. Works perfectly. I thought the case of the mic jack was grounded to the chassis? Should it be? Mine's not. I'll take the rig apart and check for a poor ground for the mic..... I know I'm close - betcha it's something stupid, eh? 73 de Ken KGØWX - Flying Pigs #-1055 Elecraft K2 #4913 - Kadiddlehoppers #11,808 _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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In reply to this post by Ken Bessler
Ken,
Sounds like you found the source - part of the ground system. I would still recommend grounding the mic jack in any case - I do that routinely as part of any K2 that I have on the bench for upgrade. For what it is worth, in the case of cables, I always look for the source of a cable break right at the point where the cord flexes most - normally right at the point where the 'strain relief' device ends - I have found this to be true especially on portable power tools, but it also occurs on mic and key cables too - cut 2 or 3 inches off the cable and re-connect everything and intermittent problems such as that vanish. 73, Don W3FPR > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]]On Behalf Of Ken Bessler > Sent: Thursday, October 27, 2005 11:43 PM > To: Elecraft Main Group; [hidden email] > Cc: Scott King - AH6KL Elecraft > Subject: RE: [Elecraft] Mic Problem? > > > Don, Scott - et all - Thanks for the help - after doing a full > reset & re- alignment then disassembling the radio to check for > GND @ mic socket pins 7&8 (ok), I re-assembled K2 #4913 and > focused on the mic again. I had ASSumed the mic was OK because > it worked FB in my Alinco 2m/440 mobile. Well...... After > checking the mic again, I found the ground braid was bad. I cut > 2" off the plug end of the cord and re-wired the plug. Works! I > looked for a fault in the old cord end and found the braid was > tattered & broken right where the clamp was. Thanks again for > the help! 73 de Ken KGØWX - Flying Pigs #-1055 Elecraft > K2 #4913 - Kadiddlehoppers #11,808 > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > 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 > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.1.361 / Virus Database: 267.12.5/150 - Release Date: 10/27/2005 > > _______________________________________________ Elecraft mailing list Post to: [hidden email] 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 |
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