K2 RX/TX Problem
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Trusty K2/100 SN#583 has a problem which is the first significant issue since building the basic K2 in Oct of 1999. The has been mostly unused (neglected?) since the K3 arrived last November, but decided to fire it up the other day and discovered that both RX and TX exhibit a broadband 'hash' sound instead of distinct CW when first turned on, both on signals received and on its transmitted signal. This problem lessens as the radio warms up and eventually disappears completely. I have used it quite a bit this weekend and it's been fine - until I turn it off for a few hours.
The frequencies for the VCO and BFO seem OK as do the voltages. Cal PLL was performed and completed without any errors. Has anyone experienced this intermittent problem before? Thanks & 73, John K1JD _______________________________________________ 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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JohnK1JD wrote:
> Trusty K2/100 SN#583 has a problem which is the first significant > issue since building the basic K2 in Oct of 1999. The has been mostly > unused (neglected?) since the K3 arrived last November, but decided > to fire it up the other day and discovered that both RX and TX > exhibit a broadband 'hash' sound instead of distinct CW when first > turned on, both on signals received and on its transmitted signal. > This problem lessens as the radio warms up and eventually disappears > completely. I have used it quite a bit this weekend and it's been > fine - until I turn it off for a few hours. > > The frequencies for the VCO and BFO seem OK as do the voltages. Cal > PLL was performed and completed without any errors. > > Has anyone experienced this intermittent problem before? Hi John! I heard you on 20m this morning. My first thought with any intermittent is always a forgotten or poor solder joint. It would be interesting if it had just appeared after all these years. I would try reseating any socketed IC's. You could selectively cool components with a freon spray to try to isolate it. Also it might help to check and see if it happens on all bands/modes or just specific ones. -- 73, Vic, K2VCO Fresno CA http://www.qsl.net/k2vco _______________________________________________ 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 JohnK1JD
John,
A broadband 'hash' sound on both transmit and receive may be the result of magnetic coupling to the VFO. As a test, I suggest that you physically isolate the K2 from anything that might contain a transformer (and that includes some lamps). If the problem reduces or disappears, then you have 2 options - 1) re-arrange your operating position so the K2 is at least 2 feet away from anything containing an AC transformer or 2) add the VCO shield kit. If isolating the K2 does not cure the problem, then you will have to do some de-bugging. The most likely areas for the source of a problem of that nature is the VFO and the BFO, and the most likely cause of a problem that responds to heat and time is a bad solder connection. 73, Don W3FPR JohnK1JD wrote: > Trusty K2/100 SN#583 has a problem which is the first significant issue since building the basic K2 in Oct of 1999. The has been mostly unused (neglected?) since the K3 arrived last November, but decided to fire it up the other day and discovered that both RX and TX exhibit a broadband 'hash' sound instead of distinct CW when first turned on, both on signals received and on its transmitted signal. This problem lessens as the radio warms up and eventually disappears completely. I have used it quite a bit this weekend and it's been fine - until I turn it off for a few hours. > > The frequencies for the VCO and BFO seem OK as do the voltages. Cal PLL was performed and completed without any errors. > > Has anyone experienced this intermittent problem before? > > _______________________________________________ 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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All
The intermittent (cold rig only) problem cited below completely disappeared upon removal of the NB and SSB boards (replacing them with the requisite jumpers and the capacitor). The KSB2 board was put back first and the rig still behaved perfectly. However, when the NB board was plugged back in the problem returned (note - the NB function is turned off). Interesting that both RX and TX are affected. More to follow... 73, John K1JD K3/100 #071 K2/100 #583 > JohnK1JD wrote: Trusty K2/100 SN#583 has a problem which is the first significant issue since building the basic K2 in Oct of 1999. The rig has been mostly unused (neglected?) since the K3 arrived last November, but decided to fire it up the other day and discovered that both RX and TX exhibit a broadband 'hash' sound instead of distinct CW when first turned on, both on signals received and on its transmitted signal. This problem lessens as the radio warms up and eventually disappears completely. I have used it quite a bit this weekend and it's been fine - until I turn it off for a few hours.The frequencies for the VCO and BFO seem OK as do the voltages. Cal PLL was performed and completed without any errors. Has anyone experienced this intermittent problem before? _______________________________________________ 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 |
Re: K2 RX/TX Problem has been localized
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John,
That sounds like a leaky capacitor on the KNB2 board. The first ones to suspect are the 0.1 uf caps with 0.1 inch lead spacing. I would suggest arbitrarily replacing all of them as the first order of business. It is strange that both TX and RX are affected because the KNB2 is only in the receive path - but then, strange things can happen. 73, Don W3FPR JohnK1JD wrote: > All > The intermittent (cold rig only) problem cited below completely > disappeared upon removal of the NB and SSB boards (replacing them with > the requisite jumpers and the capacitor). The KSB2 board was put back > first and the rig still behaved perfectly. However, when the NB board > was plugged back in the problem returned (note - the NB function is > turned off). Interesting that both RX and TX are affected. More to > follow... > > 73, > John K1JD > K3/100 #071 > K2/100 #583 > >> JohnK1JD wrote: > Trusty K2/100 SN#583 has a problem which is the first significant > issue since building the basic K2 in Oct of 1999. The rig has been > mostly unused (neglected?) since the K3 arrived last November, but > decided to fire it up the other day and discovered that both RX and TX > exhibit a broadband 'hash' sound instead of distinct CW when first > turned on, both on signals received and on its transmitted signal. > This problem lessens as the radio warms up and eventually disappears > completely. I have used it quite a bit this weekend and it's been fine > - until I turn it off for a few hours.The frequencies for the VCO and > BFO seem OK as do the voltages. Cal PLL was performed and completed > without any errors. > > Has anyone experienced this intermittent problem before? > > > > _______________________________________________ > 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 - http://www.avg.com > Version: 8.0.169 / Virus Database: 270.7.0/1683 - Release Date: 9/21/2008 10:10 AM > > 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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