Gerald I see and hear the same thing with my SDR-1000 when driven by my Presonus Firebox. The residual carrier coming out of my 1 watt SDR is at -50dBc and when I connect the Firebox I and Q outputs to the SDR-1000 the resultant carrier is now at -42dBc. The 8 dB increase is actually noise coming from the Firebox soundcard regardless of any software settings on either the soundcard or the SDR-1000. It is a hardware thing. I am trying to live with it, however, I am considering some sort of attenuator between the Firebox and the SDR to reduce the noise from the Firebox and hopefully I still have enough audio to drive the SDR to max power.
Good luck and 73 Al Ward W5LUA -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gerald Capodieci Sent: Sunday, February 11, 2007 12:36 PM To: flexradio@flex-radio.biz Subject: [Flexradio] 25. Re: Transmit noise - Computer generated with D44(kd5nwa) I wish it were ground loops. I know the hum they make. This sounds like old fashioned transistor noise that I got familiar with as a kid. I've turned the power supply off since I know the SDR does not completely turn off. I've recorded the noise with and without the mic cable plugged in and I've recorded it with all non essential cables disconnected. Now, it may be at an inconsequential level for radio communications but it does go out as a small part of the signal. Try to listen to it yourself. I can forward a copy by email if you wish. If it's truly software gain derived noise, the only solution would be to add a low level preamp between the mic and D44 box to reduce the need for the noise software amplification adds. However I'm trying to establish a minimalist station and the preamp is one more complication I'd like to avoid. I'll test with a near by station to hear if he can hear the noise in my signal. If not, I'll forget about it. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/attachment s/20070211/6edee3d0/attachment.html _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com/ FlexRadio Knowledge Base: http://kb.flex-radio.com/
