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

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

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.

"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'

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.