Hello Stefan,
for narrowband vfo i get best results with a clap or a seiler,both with big
parallel c over the FET.But of course everything depends on the mechanical
stability and the quality of the parts: ceramic coilformer,silvered mica
capacitors and tempcompensation with N750 ceramic capacitors.With trial and
error you may get very good results.Use big parts,temprise will be less,so
stability will be better..
GL
73
Victor
-----Oorspronkelijk bericht-----
Van: [email protected]
[mailto:[email protected]]Namens Stefan Schäfer
Verzonden: donderdag 5 juli 2012 18:32
Aan: [email protected]
Onderwerp: LF: Analog oscillators
LF/MF,
I want to build an analog oscillator running on 1888....1916 kHz. It
will be used as the input VFO for my PA which divides the frequency by 4
internally. A metallic box with 12V input voltage cables and a RG174
cable for the output is already available. Also a 78L05 with its 100nF
Cs is mounted. Later i can label the scale directly with 472...479 kHz,
so the need to divde by 4 in my head will not be necessary any more.
The output voltage should be arround 12V. The curve form is not
critical, it does not need to be a clear sine wave. However the
frequency should be as stable as possible.
So, what is the best oscillator circuit? Are there strong differences
regarding stability or is it always a question of the temperature? Ah,
it must be a LC oscillator. The adjusting part is a variable C of 33pF
with a 6mm axis.
There are a lot of circuits in the web but maybe one principe is to be
preferred..
73, Stefan/DK7FC
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