Question about 10MHz oscillator
I have been trying to make a 10MHz oscillator work for about 5 years. I finally got one to work and it worked for about a year and then it stopped ,but I think the problem is in the design , it was always intermittant. Does anyone know of a good oscillator circuit I can use to get about 10MHz (variable by at least 200KHz)? UNfortuinatlety I am stuck using a 14 to 380pF tuning capacitor for economic reasons. Will that work?
George
What kind of oscillator are you looking for, you didn't specify the wave type (square, triangle etc ) or the output level.
Why should it be variable, do you adjust the accuracy or some other reason.
Alex
I have tried crystal oscillators, colpitts, hartley, clapp and others too but I can't remember their names. I have tried VCO's also but mainly resonant tank circuit types with the 14-380pF air variable tuning cap (dual ganged). It is for a local oscillator on a 40M SSB transceiver. Maybe I should have chosen a lower IF, but I thought I would have trouble with the filtering. The output would be OK anywhere from around 1Vpp to 10Vpp. I could work with it. If only less is possible I could still manage to work with it. Sine wave preferably, but maybe I could use a filter to round off a square wave. I want to get at least from 10.1MHz to 10.3 MHz.
George
Lets get this right, you want a tuning capacitor of 14 -380 pF to move an oscillator from 10.3 to 10.1 MHz. A frequency change of ~2% with a capacity change of 20 :1. Lets say your stray capacity is 20Pf, add your caps min(14) gives Cmin = 34 Pf, then Cmax = 34 +4% = 36pF. The first thing I would do is to put a high quality capacitor in series with the connection to your tuner, Say 22pF with a trimmer across it. Now increase the inductance to tune to 10.1, and by tweaking the capacitors, you should get the correct tuning range. This way you will get a much better L/C ratio and any oscillator will take off unless the coil is made of steel.
Frank