n20. Xtal oscillators
Free-running oscillators, see page n18

Butler common base overtone oscillator. ARRL Handbook 1996, fig 14.23 (pg 14.25)
This type of oscillator has been very popular within RSGB. Note the extra limiting diodes which first appeared in the 90's on the common collector version, now also for common base version, suppose silicon diode 1N4148 is just as good up to 150MHz, but not as fine and expensive type.

Low-noise XO for 12MHz, based on an article by DJ2LR Ulrich Rohde in Ham Radio around 1976. Similar circuits have been applied in all my 2m/70cm/23cm beacons since 1978.
The oscillator is also shown on pg c11.

3686kHz xtal oscillator with S042P.
The oscillator is also shown on pg L1.

2nd mixer uses S042P (60kHz to 3627kHz). This the actual circuit I use, based on a device which I
have few douzens of. It seems important to balance it, and 40dB improvement were made. The xtal was
used since it was available, you could very well choose a better xtal frequency, but when the HF transceiver
(FT-902 with separate input connector) has been set once.
On page c13 is shown another S042P type mixer where 25dB carrier leakage was improved using the extra
resistor arrangement. Some data for S042P and E devices are also shown further down the page

Have been requested by LA8OJ to add this important information from Wenzel Associates:

Finesse Regulator Noise http://www.wenzel.com/documents/finesse.html
Low-Cost Phase Noise Measurement http://www.wenzel.com/documents/measuringphasenoise.htm

78L08 regulators are very popular, particularly amongst those who don't care how the signal sounds, read the note above to make a clean signal on the air!

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2004.07.14