Home |
Search |
Today's Posts |
#1
|
|||
|
|||
2m VCO?
i'm after a circuit for a 2m VCO.
basically i'm planning to homebrew a kind of tracking generator, where I can sweep across 2m to look at filter shapes, etc. my plan is to sweep, using a vco, across 2m using a sawtooth waveform. this waveform will also be amplified and fed to an oscilliscope, to give me a horizontal sweep. the output from the filter will then be fed to a RF millivoltmeter circuit (again, anyone got any good circuits?) and this will then be fed into a logarithmic converter then be put onto the Y deflection, to give me amplitude. calibration will be by putting the system into "manual" mode and connecting to a frequency counter, then sweeping up and down until get specific frequency, then the x-centering be used to set this on a known point. basically anything that having say 1-6V in giving a 140 to 150mhz sweep would be grand, then i can play with amplifiers to get it just as i want. thanks all! dr. x |
#2
|
|||
|
|||
Check out this circuit:
http://www.edn.com/archives/1998/111...s/23DI2294.pdf It will easily tune an octave with just a few volts of tuning voltage. Joe W3JDR "James Bond" wrote in message ... i'm after a circuit for a 2m VCO. basically i'm planning to homebrew a kind of tracking generator, where I can sweep across 2m to look at filter shapes, etc. my plan is to sweep, using a vco, across 2m using a sawtooth waveform. this waveform will also be amplified and fed to an oscilliscope, to give me a horizontal sweep. the output from the filter will then be fed to a RF millivoltmeter circuit (again, anyone got any good circuits?) and this will then be fed into a logarithmic converter then be put onto the Y deflection, to give me amplitude. calibration will be by putting the system into "manual" mode and connecting to a frequency counter, then sweeping up and down until get specific frequency, then the x-centering be used to set this on a known point. basically anything that having say 1-6V in giving a 140 to 150mhz sweep would be grand, then i can play with amplifiers to get it just as i want. thanks all! dr. x |
#3
|
|||
|
|||
On Mon, 24 Jan 2005 00:10:08 +0000 (UTC), "James Bond"
wrote: i'm after a circuit for a 2m VCO. basically i'm planning to homebrew a kind of tracking generator, where I can sweep across 2m to look at filter shapes, etc. my plan is to sweep, using a vco, across 2m using a sawtooth waveform. this waveform will also be amplified and fed to an oscilliscope, to give me a horizontal sweep. the output from the filter will then be fed to a RF millivoltmeter circuit (again, anyone got any good circuits?) and this will then be fed into a logarithmic converter then be put onto the Y deflection, to give me amplitude. That's called a spectrum analyser ... calibration will be by putting the system into "manual" mode and connecting to a frequency counter, then sweeping up and down until get specific frequency, then the x-centering be used to set this on a known point. Another way to provide cal information is with a comb generator. Add a controlled amount of this to your detector input and you get blips on the screen at comb spacings. Obviously have this switchable. basically anything that having say 1-6V in giving a 140 to 150mhz sweep would be grand, then i can play with amplifiers to get it just as i want. Pinch the Tx VCO out of a highband mobile. |
#4
|
|||
|
|||
"Verizon News" wrote Check out this circuit: http://www.edn.com/archives/1998/111...s/23DI2294.pdf It will easily tune an octave with just a few volts of tuning voltage. I am extremely interested in this article. I signed up with EDN over 12 hours ago, but the only thing I've gotten is that my "subscription is processing", whatever that means. So far it means that I don't have the required password to access the archive. :-( Since the subscription is free, and I've already tried completing it, can someone please e-mail me this file? 'n5qmg' 'at' 'houston.rr.com' |
#5
|
|||
|
|||
A Mini-Circuits POS-150 would do the trick.............about 22 dollars.
Pete "budgie" wrote in message ... On Mon, 24 Jan 2005 00:10:08 +0000 (UTC), "James Bond" wrote: i'm after a circuit for a 2m VCO. basically i'm planning to homebrew a kind of tracking generator, where I can sweep across 2m to look at filter shapes, etc. my plan is to sweep, using a vco, across 2m using a sawtooth waveform. this waveform will also be amplified and fed to an oscilliscope, to give me a horizontal sweep. the output from the filter will then be fed to a RF millivoltmeter circuit (again, anyone got any good circuits?) and this will then be fed into a logarithmic converter then be put onto the Y deflection, to give me amplitude. That's called a spectrum analyser ... calibration will be by putting the system into "manual" mode and connecting to a frequency counter, then sweeping up and down until get specific frequency, then the x-centering be used to set this on a known point. Another way to provide cal information is with a comb generator. Add a controlled amount of this to your detector input and you get blips on the screen at comb spacings. Obviously have this switchable. basically anything that having say 1-6V in giving a 140 to 150mhz sweep would be grand, then i can play with amplifiers to get it just as i want. Pinch the Tx VCO out of a highband mobile. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|