[time-nuts] Xtal-like Colpitts Oscillator, time-nuts Digest, Vol 44, Issue 62

David t_list_1_only at braw.co.uk
Mon Mar 31 18:18:50 EDT 2008


> Message: 2
> Date: Mon, 31 Mar 2008 21:20:43 +0000
> From: Jenny Lee <hyunjoo_lee at hotmail.com>
> Subject: [time-nuts] Xtal-like Colpitts Oscillator
> To: <time-nuts at febo.com>
> Message-ID: <BAY111-W45FBBC8E56D4B675F9F869CFA0 at phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
> 
> 
> Hi Everyone,  I was hoping to get some words of wisdom on my 
> oscillator that only oscillates in simulation!  I have .....

Are you sure it simulates? Transistor looks reverse biased, some odd looking
values, Cout too small, 10nF more probable, L2 too large, a real component
is probably well past self resonance at 34MHz, C7 too large. The direct
drive into a 50 ohm load may be ambitious, I'd have expected a buffer amp on
the oscillator output giving a higher load Z to your osc. Check the DC bias
without a resonator, check the system as a buffer without the resonator or
C1 fitted etc.

Hope this helps.

David






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