Hi Edwin, I think what you are seeing might be DDS spurs.
I just did some additional testing with my SDR1000 that's using a Delta 44, as well as some testing with a seperate SDR1000 that uses an Edirol (and a different computer). With each console setup up similarly: o SR = Off (spur reduction) o PreAmp = Med o Mode = LSB o DDS Clock Offset = 0 (this is important for comparing one radio to another!). It's in one of the Setup menus (you need to check the "expert" box). o Antenna: connect to dummy load. If I tune each Console to 7.002 MHz, I see spurs at exactly 1 KHz spacing. If I then detune by *only* 1 Hz (that's Hz, not KHz), the spurs change frequency by an amount much greater than 1 Hz, which is what I would expect for DDS-generated spurs. Both my system with the Delta 44 and my system with the Edirol experience the same problem. Note too: one of the spus (I think it's the one at 7.001 MHz) I can attenuate by attaching a Radio Shack common-mode choke in series with the cable attached to the "To Line Out" jack of the SDR - so there seems to also be a second source for a spur at this frequency, and thus some interaction between it and the DDS spur on the same frequency). And, if I change the vfo by 1 Hz, it moves by the same amount, too, again implying that it's not DDS spurs. Usually DDS spurs aren't a problem, because, except for certain frequencies (around 7.15 MHz on my radio, for example), their amplitude lies below the "atmospheric" noise floor. Try testing your other frequencies, too, that you show in the video. If you move the frequency by only 1 Hz, do the spurs move by the same amount, or by a much different amount? - Jeff, k6jca Edwin Marzan wrote: > Hi Jeff, > > The setup is very simple. Astron VS-20M Power supply, SDR-1000, Eridol > FA66, HP Computer, MFJ Tuner (no power supply), Creative Labs > Speakers. Switched on and off all other equipment at home and no luck. > Receiver is calibrated with Elecraft XG-1. IF was changed from 11.25 > (I think) to 9 or somesuch via PowerSDR. Noise level is very high here > in the Bronx. I see the same high levels with my other transceivers. I > don't see any other patterns other than 1 khz spacing that you noticed > on the waterfall display. I'm going to see if my older version of > PowerSDR exhibits this same behavior. > > Thanks for the suggestions! > > Edwin Marzan > AB2VW > > > ===================================================================================================== > > > > Date: Thu, 10 Jan 2008 10:31:17 -0800 > > From: [EMAIL PROTECTED] > > To: [EMAIL PROTECTED] > > CC: flexradio@flex-radio.biz > > Subject: Re: [Flexradio] Mysterious Spur Visible on Panadaptor > > > > Mike's (w6thw) suggestion is a good one. Switch off all other equipment > > and see if it goes away. > > > > Also - your noise floor looks pretty high to me (compared to what I see > > on my SDR). What is your preamp set to? The high noise *may* be > > indicative of an incorrectly calibrated receiver - do you have a good, > > calibrated, RF source that you can use to calibrate the receiver > > levels? I'm wondering if these tones are actually really far down in > > level (below the A/D's threshold), but, because input gain is too high, > > they're being digitized by the A/D and appearing as real (albeit faint) > > signals) - but I'm really just guessing here. I don't know if the > > Edirol has a preamp prior to the A/D (many A/D's do), nor if Flex > > controls the gain of this preamp. If not, that is, if gain is only > > applied in software, then this thought is probably wrong - but you may > > still need to calibrate the receiver. > > > > By the way, if you don't have a calibrated RF generator that you trust, > > Elecraft makes one that is perfect for something like this (I recommend > > that all hams have one). > > > > If you're still not having any luck, more clues might be gained by > > looking at the entire panadapter display (zoom all the way out) . Are > > there any patterns? > > > > Also - what's the IF frequency set to? > > > > Thanks, > > > > - Jeff, k6jca > > > > > > > > Edwin Marzan wrote: > > > Hmmm.... there is a switching power supply powering another > transceiver nearby. I'll see what happens when I turn it off. > > > > > > Thanks for the info.Edwin MarzanAB2VW > > > > > > > > > Date: Thu, 10 Jan 2008 09:09:48 -0800From: > [EMAIL PROTECTED]: Re: [Flexradio] Mysterious Spur Visible on > PanadaptorTo: [EMAIL PROTECTED] > > > Hi are you using a switching power supply if so try another one > and see if it still there. > > > Just thought it might be the same thing i had happen on all bands. > > > > > > > > > ------------------------------------------------------------------------ > Put your friends on the big screen with Windows Vista® + Windows > Live™. Start now! > <http://www.microsoft.com/windows/shop/specialoffers.mspx?ocid=TXT_TAGLM_CPC_MediaCtr_bigscreen_012008> _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
