#5957 w/ DSP, NB, SSB seems to have developed an RF noise problem. With the radio setup this way: > antenna connected to dummy load, DSP off, NB off, AGC off, CW mode, AUD fully advanced
I get the following symptoms: > as RF gain is advanced a "frying noise" comes up, reaching about S5 at max RF. > switching preamp/attenuator in and out doesn't change the problem "noise." I can hear real RF noise from the dummy load and preamp increase/decrease on top of the problem "noise." > changing the XTAL filter setting does change the "noise." > as the RF control is reduced from max to min, at about 2/3 max a soft "pop" is heard, the the S-meter reading goes all the way to max [as if the RF gain were fulling off] and then trails back towards S-0 as it was before the "pop." Afterwards, the S-meter reading continues to max as normal. It's as if the AGC were on, but it isn't. > switching AGC in/out doesn't alter the "noise." > switching DSP in alters the "noise" as the DSP circuit tries to handle it. As compared to the no-DSP condition, the "noise" with DSP comes up as brief static "spikes" that eventually blend into sound of the "noise" w/o DSP. > switching NB in/out doesn't alter the "noise." In view of the above, I'm thinking that this noise is coming from Rcv Mixer [TUF-1] - Post-Mixer Amp [Q22] circuit area. Nothing before that seems to effect it, and the XTAL filter definitely reduces it. Any quick insights or trouble shooting steps that can help me reduce/eliminate this "noise" would be appreciated. Thanks much. ...robert Robert G. Strickland, PhD, ABPH - KE2WY [email protected] Syracuse, New York, USA ______________________________________________________________ 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
