Roland_DF1OE wrote: > Last Year i built my k1 #3310...
Excellent choice! > I ve a little problem - may be it is quite normal... What you describe below is very abnormal. > during sending cw the sidetone is very very loud - louder as it is during > adjusting ST_L and much louder than testing it with no cw HF transmission. > > During transmission it gets louder after a time. Even if i put ST_L to 1 > (one) i get a loud sidetone during cw hf transmission. My first guess would be some disturbance at front panel board FP-U2, the DAC which actually produces the sidetone. The DAC uses Vdd from the 6.0 vdc regulator FP-U4 as its reference voltage. Perhaps you have some RF intrusion or regulator load change during transmission that is upsetting the regulated Vdd at pin 7 of FP-U2 that is coming from regulator FP-U4. Such regulators can become unstable if there is not a small capacitor on the output, although the ZR78L06 is not supposed to need one. Regardless, the FP board has such a capacitor (FP-C5, 0.01 uuF) mounted on the "bottom" (back or rear) side of the FP board. I would check that it is in place, and properly soldered. FWIW, here's the MAX518 data sheet: http://datasheets.maximintegrated.com/en/ds/MAX517-MAX519.pdf Of course, perhaps it is something completely unrelated. But it is definitely abnormal. This is what I'd check first. 73, Mike / KK5F ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
