Don Wilhelm-4 wrote: > > I wonder why this has not been seen before - surely many have used the > internal speaker over the past 3 years, but then again, perhaps not > often, I use external speakers, and many use headphones. >
I don't know why, Don. Perhaps it's because you really need a K3 to clearly hear a signal 60dB down at 600Hz separation. :) But I was able to reproduce the effect and hear it on my FT-817. Set two receivers to CW on the same frequency. Select the narrowest filter on the receiver. Attach the K3 to a leaky dummy load and set the power level such that it produces a strong signal in the receiver without overloading it. Use headphones with good acoustic isolation on the receiver. Tune the receiver so the signal is zero-beated. Then increase the sidetone monitor level. It may be hard to hear, because on my K3 at any rate I needed to increase the monitor to an uncomfortably high level before I could clearly hear the keying through the headphones, and the monitor tended to drown out the spurious signal I was listening for. But by varying the monitor level it was clear that I was hearing a spurious signal separated from the main one by the amount of the sidetone frequency. I couldn't produce a Spectran plot to illustrate the spurious next to the main signal because distortion harmonics of the main signal (presumably caused by the FT-817 audio stages) masked the weak spurious signal. Someone with a panadapter might be able to see it. Since I never use more than 100W into fairly poor antennas and normally set the sidetone at a quiet level (4 or thereabouts) I can't see this being a issue for me personally. If a mod is produced to fix this I think it is one more mod that I won't bother doing. But someone who uses high power into a beam and has the monitor turned up loud might well have a problem unless they use headphones or external speakers. ----- Julian, G4ILO. K2 #392 K3 #222. * G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html -- View this message in context: http://n2.nabble.com/K3-spurious-tp4201459p4203908.html Sent from the [K3] mailing list archive at Nabble.com. ______________________________________________________________ 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
