ECL oscillator just won't oscillate

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FET Choice

Hi Jocko,
Of all the bipolar transistors and FET's tried the J309 was giving the best <B>SOUNDING</B> result.
I tried BC550C; 2N4401 (best of all bipolars); 2N2369A; half a MAT02; 2SK117BL; 2SK161GR (giving problems), J309; J310 (works as well); U440 in the Wildmonkeysects circuit (did not work)
My way of working may strike you. Being a chemist by education I find the PRACTICAL result i.e. the sound the most important issue.
The KWAK-CLOCK is the result of my experiments using my ears as the ultimate judgement.
Same story for the comparator. I started with the LT1016; AD9696 and switched to AD8561.
Did you know that LCAudio uses a 5 GHz transistor? Speaking of overkill.;)
<I>BTW the 0.01 µF coupling cap between FET and comparator and the 100k resistor are superfluous. Omit these components and directly connect the source of the FET with the positive input pin#2 of the comparator (no change in sound though)</I>Helas.:)
 
comparator vs. PECL/TTL converter

Hi Elso,

the reason for the observed ("obheard"?) differences might be that a comparator will work with a very small sinusoidal input signal whereas an ECL input needs a couple of 100 mV for a full swing. Also, even a PECL devices primary reference for all input signals is not ground but the positive supply.

Apart from the old Moterola ECL data books and app notes which are still available as PDFs at OnSemi, Tietze/Schenk, "Halbleiter-Schaltungstechnik" is very instructive. The 11th edition has been expanded also to give much more information on how to design current sources and op-amps, both in discrete and integrated design. I haven't found this much concentrated information anywhere else yet.

Greetings,

Eric
 
Audio transistors in RF oscillators

Just so you guys won't think I am closed-minded about evertything, I tried the old standby......2SC2240.....(sonnya, are you reading this? Heh-heh.) in the oscillator I posted.

Same voltage output. So, what next........

Build two more, one with '918, one with '2240. Get a mixer out of the old junk box, and use one with a '2240 as the reference oscillator. Compare the downconverted spectrum on my FFT (when I get it back that is: on loan.) Then we can come up with a relative phase noise measurement.

Standby for results, just don't hold your breath.

Jocko
 
Sorry Elso,

I should have reread the last couple of threads. Somehow, I was sure you observed the sonic differences between ECL convertor and comparator, but I was wrong!

I have been doing analog electronics for ages, and I had digested the previous editions of Tietze/Schenk thoroughly. Still, I found many things I didn't know or had been trying to find for a long time in the new edition. The reason is that is has been expanded to cover integrated analog circuit design. Most of the things can be applied to discrete circuits, too, if you throw in a couple of degeneration resistors to deal with transistor matching problems.


Groetjes,

Eric
 
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