Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Question about 10MHz oscillator

Status
Not open for further replies.
O

obrien135

Full Member level 5
Joined
Nov 10, 2009
Messages
240
Helped
5
Reputation
10
Reaction score
5
Trophy points
1,298
Location
Connecticut
Activity points
3,259
Hello,

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
 
Last edited:

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
 
Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top