100mhz oscillator circuit - Electronic Circuits Projects Diagrams Free

gray5596 · 6th May 2008, 04:42 AM

Greetings from a new guy. I am looking for a reasonably stable 100mhz oscillator circuit. (Any frequency from 90 to 105mhz would work well.) My application is for a portable spectrum analyzer that is driven by a YIG (and lacks a tracking generator) so at lower frequencies, it drifts a bit. I plan to use this oscillator to generate a marker signal for a reference in the FM range. Any help or alternate ideas would be appreciated.

crutschow · 6th May 2008, 05:14 AM

I assume you mean megahertz not millihertz.

Is there some reason not to use an off-the-shelf crystal oscillator module? For example, Digi-Key sells many such units with some costing only a few dollars.

gray5596 · 6th May 2008, 06:05 AM

Sorry, I didn't proof-read my words very well. You are correct, I meant megahertz. (At 100 millahertz, I'd probably get the attention of an angry whale

)

I'm looking for something simple so the idea of a pre-made crystal oscillator sounds great. However I have a few questions. Wouldn't it be a fairly low level output? In other words, wouldn't I have to take the output from it and use it to drive a transistor to get a strong enough signal for my analyzer? Or were you thinking about driving the analyzer directly instead of transmitting the signal thru the air?

crutschow · 6th May 2008, 06:12 PM

Quote:

Originally Posted by gray5596

I'm looking for something simple so the idea of a pre-made crystal oscillator sounds great. However I have a few questions. Wouldn't it be a fairly low level output? In other words, wouldn't I have to take the output from it and use it to drive a transistor to get a strong enough signal for my analyzer? Or were you thinking about driving the analyzer directly instead of transmitting the signal thru the air?

I did think you would be injecting the signal directly. So this is an analyzer with an antenna input?

One oscillator I looked at from Digi-Key (ECS-3951M/3953M-AU) has a 5V output. Attaching a short wire to the output should give a reasonable signal through the air for short distances, likely enough to be readily observed by the analyzer. Probably would also foul up FM reception at that frequency for a significant distance.

Boncuk · 6th May 2008, 09:19 PM

Best bet is a TCXO. They have an initial accuracy of +/- 1ppm.

Check at http://www.vectron.com

crutschow · 6th May 2008, 11:00 PM

Quote:

Originally Posted by Boncuk

Best bet is a TCXO. They have an initial accuracy of +/- 1ppm.

TCXOs are good if you need that much stability. But they are more expensive and gray5596 stated he needed a "reasonably stable" oscillator which I interpreted to mean that the stability of a standard crystal oscilllator would suffice.

gray5596 will need to decide how much stability he needs (or wants to pay for).

gray5596 · 9th May 2008, 01:59 PM

Thanks for the ideas, you pointed me to a much easy solution.

I was trying to make this too hard by making it transmit thru the air, when all I had to do was take crutschow's advice and use a standard pre-made oscillator and feed this directly to the analyzer.

I experimented with a couple of different oscillators and it worked quite well. Mission accomplished!

6th May 2008, 04:42 AM	(permalink)
gray5596 New Member	100mhz oscillator circuit Greetings from a new guy. I am looking for a reasonably stable 100mhz oscillator circuit. (Any frequency from 90 to 105mhz would work well.) My application is for a portable spectrum analyzer that is driven by a YIG (and lacks a tracking generator) so at lower frequencies, it drifts a bit. I plan to use this oscillator to generate a marker signal for a reference in the FM range. Any help or alternate ideas would be appreciated.

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6th May 2008, 05:14 AM	(permalink)
crutschow Experienced Member	I assume you mean megahertz not millihertz. Is there some reason not to use an off-the-shelf crystal oscillator module? For example, Digi-Key sells many such units with some costing only a few dollars.

6th May 2008, 06:05 AM	(permalink)
gray5596 New Member	Sorry, I didn't proof-read my words very well. You are correct, I meant megahertz. (At 100 millahertz, I'd probably get the attention of an angry whale ) I'm looking for something simple so the idea of a pre-made crystal oscillator sounds great. However I have a few questions. Wouldn't it be a fairly low level output? In other words, wouldn't I have to take the output from it and use it to drive a transistor to get a strong enough signal for my analyzer? Or were you thinking about driving the analyzer directly instead of transmitting the signal thru the air?

6th May 2008, 09:19 PM	(permalink)
Boncuk Experienced Member	Best bet is a TCXO. They have an initial accuracy of +/- 1ppm. Check at http://www.vectron.com

9th May 2008, 01:59 PM	(permalink)
gray5596 New Member	Thanks for the ideas, you pointed me to a much easy solution. I was trying to make this too hard by making it transmit thru the air, when all I had to do was take crutschow's advice and use a standard pre-made oscillator and feed this directly to the analyzer. I experimented with a couple of different oscillators and it worked quite well. Mission accomplished!