Ray, OK since the tone dd not stop during a TUNE, that places the problem after transistor Q10. Refer to the schematic for the RF board sheet 1 in the lower left corner - everything there is suspect. You should be able to short U4 pin 3 to ground and kill the sound - if that is true, the problem is with the U3, Q10 or Q11 stages and their associated components. If shorting U4 pin 3 to ground does not stop it, it is a problem with U4 and its components.
Be aware that a leaky capacitor (in conjunction with a resistor) can create an unintended oscillator. Replacement of capacitors may be in order - but unfortunately, I cannot tell you which ones. As a bit of history -- at one time, the KX1 0.1 uF capacitors were a problem (problem now fixed), but the 0.1 uF capacitors in the K1 are not the same - however, if you substituted a blue body 0.1 inch lead spacing capacitor for a 0.1 uF capacitor used for the K1, then that is suspect. "Tis a mystery right now - let's hope it can be found in short order. I would re-flow the soldering at U3 and U4 just to see if a soldering problem is the cause. I suspect it is - and your opening the K1 to install the KNB1 just accelerated an impending failure point. 73, Don W3FPR On 1/10/2012 4:52 PM, Ray Spreadbury wrote: > Hi Don > The "whine" is a steady continuous tone (perhaps at 800 or 900 cycles), not > popping, nor a low pitched oscillation and in fact I wondered if the > sidetone spot was on or if the key was down. > It does vary in level with the AF gain control but doesn't change in pitch. > It is present whether there is a signal being received or not. It is still > present if I do a tune. > > 73 > Ray G3XLG > > -----Original Message----- > From: Don Wilhelm [mailto:[email protected]] > Sent: 10 January 2012 20:35 > To: Ray Spreadbury > Cc: [email protected] > Subject: Re: [Elecraft] K1 Audio Problem after fitting KNB1 Noise Blanker > > Ray, > > Please describe the "whine" in more detail. Is it more of a "popping" > noise, or is it a low ptched oscillation, or is it a high pitched > squeal, or something else. > Does it vary with the AF gain control or is it more constant - if it > varies, does it change in level, or pitch or both? > Does it vary when tuning through a strong signal - how about a weak one, > or is it present whether there is a signal being received or not. > > If you do a TUNE (connect a dummy load first), is it silenced or is it > still present. > > 73, > Don W3FPR > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
