Hi Stefan,

the W1VD link looks very nice,the dual gate mosfet is a very good buffer
circuit to prevent pulling.Getting the best stability you probably won't
manage in an evening but making it work won't be a problem.I do have all the
stuff to be active on 500 KHZ and I made it over the pond.At this moment
however I am more active making low power qrss beacons on HF,30m and
40m.Maby one of these days I will setup 500KHz again and work you on this
band.

73

Victor

-----Oorspronkelijk bericht-----
Van: [email protected]
[mailto:[email protected]]Namens Stefan Schäfer
Verzonden: donderdag 5 juli 2012 19:10
Aan: [email protected]
Onderwerp: Re: LF: RE: Analog oscillators


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
>
>
>
>
>