[AReU] 10 MHz TCXO

[Tony Stone]

I finally got my stuff together this weekend and built a 10 MHz 
frequency standard. 

I had purchased a 10 MHz TCXO some months ago and had not 
built the circuit because the TCXO used a 3.0 VDC power supply. 
This weekend I was down at Practical Electronics and picked up 
some LM317 variable voltage regulators. They will control 1.5 VDC 
up to above 30 VDC. 

I built up a cascade voltage regulator with a 7808 feeding into an 
LM317 set to 3.0 VDC to give an extra stable power supply. 

After finding out that the output was rather low from the TCXO, 
I added a buffer amplifier with an MSA0404 MMIC. This boosts the 
output to about 300 mv (peak to peak) and also prevents "pulling" of 
the TCXO when the load changes. I used the 8.0 VDC supply to 
operate the MMIC amplifier. 

I have set my receiver to WWV on 20 MHz and have adjusted the 
TCXO until the difference frequency has a period of  greater that 5 
seconds. That is a basic 10 MHz accuracy of 0.1 Hz. 

I will bring it to AREU next Tuesday. If anyone has a frequency counter 
that needs calibration, bring it along. 

73

Tony