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Transistor impedance tolerance for Trimless VCO ? - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


SteveR
Post subject: Transistor impedance tolerance for Trimless VCO ? Posted: Wed Nov 09, 2005 6:32 am
I would like to do away with the trimmers on an existing VCO design (circa 250 MHz). The analysis thus far suggests this could work (basic tolerance analysis on passive parts, Varactor and PCB parasitic tolerance) BUT I have yet to determine the affect on tuning due to transistor tolerance. Can anyone suggest how I might approach this ?
The transistor in question is NE85630.

Thanks in advance


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Guest
Post subject: OscillatorPosted: Wed Nov 09, 2005 7:23 pm
Unfortunately, the sensitivity to transistor characteristics of an oscillator is highly circuit-dependent. You'll need to tell us what kind of circuit you have. Some versions of SPICE have the ability to do Monte Carlo simulation with tolerances - that may help.

Good Luck


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SteveR
Post subject: Transistor impedance tolerance for Trimless VCO ?Posted: Thu Nov 10, 2005 12:25 pm
The oscillator circuit is a bog standard common emitter colpitt's.



Posted  11/12/2012

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