Verry interesting Jeff, A good tool, the freeze buton 73 de peter pa0pvn groeten Peter website www.pa0pvn.tk <http://www.pa0pvn.tk/> petervn-at-hetnet-nl pa0pvn-at-hetnet-nl pa0pvn-at-amsat-org only large files: pa0pvn-at-gmail-com There are 10 kind of people, those who can count to 1010 on their fingers, and those who count to 1111111111.
________________________________ Van: [EMAIL PROTECTED] namens Jeff Anderson Verzonden: za 12-1-2008 1:15 Aan: flexradio@flex-radio.biz Onderwerp: Re: [Flexradio] Mysterious Spur Visible on Panadaptor I just ran some additional tests on 3.797 MHz (this frequency per Edwin's original video). You can read my writeup at my blog: http://k6jca.blogspot.com/ - Jeff, k6jca > -------------------------------------------------- > From: "Jeff Anderson" <[EMAIL PROTECTED]> > Sent: Friday, January 11, 2008 2:23 PM > To: "Edwin Marzan" <[EMAIL PROTECTED]> > Cc: <flexradio@flex-radio.biz> > Subject: Re: [Flexradio] Mysterious Spur Visible on > Panadaptor > > > By the way, Edwin - it's possible that what you're > seeing *aren't* DDS > > spurs. I'll do some more testing here, too, over > the weekend. > > > > Do you happen to have a Radio Shack common-mode > filter? > > > > - Jeff > > > > Jeff Anderson wrote: > >> 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. > === message truncated === _______________________________________________ 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/ _______________________________________________ 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/
