HI, Has anyone considered the Analog ADG601 / 602 parts? The bandwidth at 4.5ghz is either "too" impressive but for a QSD Im considering them.
-Mike. OH2FCZ --- In [email protected], Cecilio Bayona <[EMAIL PROTECTED]> wrote: > > [EMAIL PROTECTED] wrote: > > 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 > > > > > > Dual gate FETs should work just fine, back some time they were > considered the cat's meow since they worked so well, they could handle > large signals without distortion (high IP3) especially when used in a > balanced circuit. While being a mixer they can also provide gain. > > They are a little hard to get since very few are made anymore, they were > excellent for a receivers RF/IF amplifier since changing the bias on the > second gate could be used to control the gain of the device, and are by > nature very low noise devices. > > Their big gotcha is that they are incredibly sensitive to static, so are > easily damaged, I would solder them in place before removing the little > wire that was wrapped around the pins > > The SA612A will also work fine also as long as you stay within the chips > input level. By they way I read that they no longer manufacture the DIP > package versions, they now only make the SMT version so enjoy them while > you can, I have about 20 in stock, they are handy little devices. > > AMD makes a much better version that sports two mixers and a built in > Quadrature clock generator. You feed it a clock at 2X the receiver > frequency, and it generates the Quadrature clocks for the mixers inside, > it also has a much higher IP3 figures of +19dB, it cost around $4.00, > it's available in SMT only. > > Under 20M I prefer switches, but any kind of mixer will work, just some > better than others. Here is a schematic of a receiver with I/Q audio but > uses a Diode Balanced Mixer, there are all kinds of possibilities out there; > > < http://www.hpsdr.com/Public/Parts/Clock/TMschematic.pdf > > > > Too much fun and not enough time. > > > -- > > Cecil > KD5NWA > www.qrpradio.com www.hpsdr.com > > > "Sacred Cows make the best Hamburger!" Don Seglio Batuna > 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/
