Re: 3560 Crystals from eBay
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Looking at the circuit – the oscillator is not loaded too heavily by the PA (it ‘sees’ a high impedance at the input of the PA), so no changes there. One simple thing to try is to pull the 2N3904 and replace with a 2N2218, 2N5179, or something NPN and metal-canned with a higher alpha….use a transistor tester to pick a suitable one. Another option is to replace R1 with a slightly lower value; this pulls up the voltage at the base of the 2N3904 and may help it kick on…………this is a non-engineers look, but an oscillator is simply an amplifier with at least unity gain and feedback into the input…..
From: Bob Groh bob.groh@... [4sqrp]
Sent: Thursday, May 4, 2017 20:43
To: 4sqrp@...; Jim Sheldon
Subject: Re: [4sqrp] 3560 Crystals from eBay
Ouch. Not good news but hopefully someone will find a cure. Ah, well. Switching to 3560 is a good idea - we just have some implementation problems. Thanks for your work.