> I've noticed that when I'm tuning around 4.8 MHz to 5.3 MHz, > I can hear EMI in the form of a motorboat sound whenever I > turn a front panel knob. It's most apparent when spinning > VFO A or VFO B knobs, but also occurs when turning the filter > knobs.
I have a slight bit of noise when tuning only in that area. I believe it to be entirely normal. I recall Wayne saying somewhere that the DDS operated in the area of 5 MHz and that was synthesizer switching noise. In my case, the noise is about S1 on an S-meter that was calibrated to the XG-2 and is in "abs" mode. In my case the noise is only audible in the main Rx with VFOA or XIT/RIT when XIT/RIT is enabled ... or in the sub RX with VFOB or XIT/RIT when XIT/RIT is enabled. The noise is masked by band noise with an antenna connected. It is audible only from 4.900 to 5.100 and only noticeable from 4.940 - 5.050 unless one it looking for it. As you say, it is not present when the VFO or RIT knobs are at reset ... it is not a problem here. 73, ... Joe, W4TV > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of James Sarte > Sent: Saturday, February 28, 2009 5:27 PM > To: [email protected] > Subject: [Elecraft] Weird EMI issue... part deux > > > OK gang, I don't know what to do at this point and you're my > last line of defense before sending this rig back to Elecraft > engineering for analysis. > > > > I'll sum it up briefly: > > This is rig #2730. I bought it in kit form, and assembled it myself. > > It has a sub receiver, 100w amp, KDVR3, KAT3 tuner, > transverter, plus a full complement of filters on both receivers. > > I also have a single general coverage receive module > installed on the sub receiver. > > > > This is the problem: > > I've noticed that when I'm tuning around 4.8 MHz to 5.3 MHz, > I can hear EMI in the form of a motorboat sound whenever I > turn a front panel knob. It's most apparent when spinning > VFO A or VFO B knobs, but also occurs when turning the filter > knobs. If I don't touch anything, no noise occurs. I can > also hear this noise faintly when I'm around 3 MHz. There is > no front-panel generated noise anywhere else from .5 to 54 > MHz other than 3 and 5 MHz. Also, if I don't have the sub > receiver on and I'm only listening to the main receiver, the > EMI noise isn't as loud when the pre-amp is on. If I turn > the pre-amp off, the EMI generated from spinning knobs > increases in volume. When I spin a knob and hear this noise, > I can also see the S-meter move in correlation with the > noise; spiking at S-7 from time to time. This tells me that > this is locally generated interference, and occurs somewhere > within the K3's circuitry. Turning the pre-amp on or off has > no effect on the sub-receiver; the noise is still present. > > > > Here's what I've done: > > I've replaced the SUBIN board because I thought it was only > the sub-receiver being affected at one time, but it didn't > help. I've also swapped mixers and synthesizers with no > positive result. I've disassembled and reassembled the entire > front panel 4 times already, and cannot find anything wrong. > I've traced circuits on the sub receiver and SUBIN boards and > everything checks out. I've also swapped TMP cables around > with no improvement. I've also removed just about every > module except the transverter and KAT3 hoping to eliminate a > problem module, but the problem still remains. I've also > checked every screw and washer throughout the radio, and they > all match the assembly instructions. > > > > I'm starting to think that there may be an isolation problem > with the main RF board at this point. BUT, since I was not > able to test the rig without the KAT3 tuner or removing the > transverter board, I cannot be 100% sure. > > Is there anything else I can check before sending the rig > back to Elecraft??? > > > > Apart from this problem, I have not experienced any other > issues with this radio. In fact, it works PERFECTLY well.. I > should probably tell myself to live with this noise, but > after spending 4k, I don't want too. > > > > Suggestions people? Please help a fellow ham out. > > > > 73, > > James KC2UEE > > > > > > > > > > > > > > > > > > > > ______________________________________________________________ > 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
