Recently I have been building and testing my Dual Gate FET QSD idea. I am not finished yet but one thing I was warned about was IMD. So I decided to try a Class A bias scheme and later I will check the harmonic distortion and other needed testings. Anyways I will continue to build it and then see if there is a way to over come any IMD. I am hoping Class A is the approach. I have one FET section built on the same breadboard as I have been building a Huff & Puff VFO. The Fet I am using can output enough power to directly feed the sound card.
So far I have tested it for good sine wave reproduction from 1 to 30 MHz and it passes that, next I need to test it with square waves. If in the end of test the FET idea does not fly then I guess I will stick to the SA612A. I think it was Cecil or JR who mentioned sampling the i.f. with this circuit after the mixer stage before the i.f. filter and all of the gain. That is the idea. I have been looking at NTE's line of radio IC's to see what sort of receiver ideas one can get from their line up of chips. NTE has quite a few IC's specifically for radio. Mixers, balanced mixers, oscillators, i.f. agc sections, etc. The test output of my H101 receiver's DDS will allow me to have a LO IN that I can change the offset of by setting of the frequency by the receiver's software. I can then determince the exact ideal offset to be used with any QSD idea I try and then sellect the crystal or oscillator for that DDS frequency I used. The DDS out feature is handy. I have wondered if there is a way that in the future one could control a Huff & Puff VFO via a micro controler? I can not at this moment think of how. I did hear that some folk were looking into it and I hope I can find that info. Go to <http://fairradio.com/> and look up "Nida Trainer Model 130" #NIDA 130 for $49.50 It is a breadboard trainer with power supplies and meters and makes a nice design center. In its catalog photo it appears to have three breadboards. I will order one here this week. Dan _____________________________________________________________________ PrivatePhone - FREE telephone number & voicemail. A number so private, you can make it public. http://www.privatephone.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/soft_radio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
