Hi Victor,
Am 05.07.2012 19:00, schrieb [email protected]:
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.
OK, tnx. Years ago i built a 137 kHz oscillator (by DJ2EY) which used
diffent capacitors for temperature compensation. I will see what i get...
Use big parts,temprise will be less,so
stability will be better..
That sounds convincing, tnx. Meanwhile the output stage is built, once
again using a ICL7667. I would like to use a JFET. And i found a nice
link in the web, of course from W1VD: http://www.w1vd.com/16080VFO.pdf
That is nice and i have all the parts here. I will build it and hope to
try it in the evening :-)
BTW are you QRV on 500 CW as well?
73, Stefan
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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