Variable Square Wave to Sine Wave
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From: Robert Baer on 10 Mar 2010 01:44 Nial Stewart wrote: >> Two, with all due respect to my learned colleague, instead the of ARRL >> handbook, try >> >> Experimental Methods in Radio Frequency Design, by Campbell, and >> Hayward, its more geared to modern, simple, home made gear then the >> ARRL handbook is , sadly... > > I've just had a look at amazon.co.uk (not available) then amazon.com. > > 4 Used available from _$498.97_ (up to $937.87). > > > It would need to be good at that price! > > > Nial. > > Try Abe or other used bookstore.
From: Robert Baer on 10 Mar 2010 01:45 Muzaffer Kal wrote: > On Tue, 9 Mar 2010 13:30:21 -0000, "Nial Stewart" > <nial*REMOVE_THIS*@nialstewartdevelopments.co.uk> wrote: > >>> Two, with all due respect to my learned colleague, instead the of ARRL >>> handbook, try >>> >>> Experimental Methods in Radio Frequency Design, by Campbell, and >>> Hayward, its more geared to modern, simple, home made gear then the >>> ARRL handbook is , sadly... >> I've just had a look at amazon.co.uk (not available) then amazon.com. >> >> 4 Used available from _$498.97_ (up to $937.87). >> >> >> It would need to be good at that price! >> >> >> Nial. >> > > It seems to be available at ARRL for $49.99: > http://www.arrl.org/catalog/?category=Circuit+Design#9239 ....so...if you want fresh oats, get them at the front of the horse...
From: JosephKK on 10 Mar 2010 08:58 On Mon, 8 Mar 2010 07:29:40 -0800 (PST), FyberOptic <fyberoptic(a)gmail.com> wrote: >Hiya folks. I've been interested in trying to build myself a radio >receiver for various bands, primarily as a learning experience. The >thing is, though, I've heard that it's kind of hard to build a stable >VFO above 50mhz. One of the bands I'd eventually like to receive is 2 >meters (144-148mhz). Might be fun to receive television audio, as >well. Not to mention, standard FM. > >Since I'm more familiar with digital electronic components rather than >analog, I've seen that there are programmable frequency oscillator >ICs, which can be set via a microcontroller. This sounds like an easy >solution for tuning, and would open the door to setting station >presets and the like as well. The problem is, I'm fairly sure that >these would output a square wave. > >I've read about how you can basically use a low-pass filter to tune >out harmonics of a square wave and get a sine wave output. But from >the way I understand it, an RC filter would just filter out a specific >frequency, defeating the purpose of the variable oscillator. > >So that's pretty much my question: How does one turn a variable >square wave into a sine wave? > >Or, alternatively, what are more reliable ways to produce higher >frequency sine waves to begin with? Though I'm still interested in >the former question as well, for curiosity's sake. > >Thanks! > >- Jeff > There are sine wave DDSs out there that do milliherts to 40 MHz or so. a little heterodyning to get LO up to several hundred MHz and have fun. Too bad they are not all that inexpensive. Plus you still have a lot of work to do afterward. Start by studying superhetrodyne radios. Most the rest follows from there. Also take a look at some direct conversion systems.
From: JosephKK on 10 Mar 2010 09:13 On Mon, 8 Mar 2010 11:18:40 -0800 (PST), osr(a)uakron.edu wrote: >One, google "softrock radio" > >Two, with all due respect to my learned colleague, instead the of ARRL >handbook, try > >Experimental Methods in Radio Frequency Design, by Campbell, and >Hayward, its more geared to modern, simple, home made gear then the >ARRL handbook is , sadly... > >then look at >http://www.kangaus.com/2m_converter.htm > >then >http://www.pongrance.com/ > >the old kit > >Steve Oh yeah. That got the old Jones going again. And now i have scope enough.
From: Michael A. Terrell on 11 Mar 2010 01:19
Nial Stewart wrote: > > > Two, with all due respect to my learned colleague, instead the of ARRL > > handbook, try > > > > Experimental Methods in Radio Frequency Design, by Campbell, and > > Hayward, its more geared to modern, simple, home made gear then the > > ARRL handbook is , sadly... > > I've just had a look at amazon.co.uk (not available) then amazon.com. > > 4 Used available from _$498.97_ (up to $937.87). > > It would need to be good at that price! > > Nial. <http://www.abebooks.com/servlet/SearchResults?an=Hayward&bi=0&bx=off&ds=30&recentlyadded=all&sortby=17&sts=t&tn=Radio&x=61&y=16> has Introduction to Radio Frequency Design (ISBN: 0134940210 / 0-13-494021-0) H.H. Hayward -- Greed is the root of all eBay. |