http://qrp-popcorn.b...el/Harmonic VXO
Welcome to LN-Electronic
เพื่อการใช้งานได้อย่างเต็มประสิทธิ์ภาพ โปรดลงทะเบียนเป็นสมาชิก เพื่อที่คุณจะได้ รับข้อมูลข่าวสารอย่างครบถ่วน และ รับสิทธิ์ ในการเข้าชม และดาวน์โหลดได้อย่างเต็มรูปแบบ.
Register now to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more. If you already have an account, login here - otherwise create an account for free today!
เพื่อการใช้งานได้อย่างเต็มประสิทธิ์ภาพ โปรดลงทะเบียนเป็นสมาชิก เพื่อที่คุณจะได้ รับข้อมูลข่าวสารอย่างครบถ่วน และ รับสิทธิ์ ในการเข้าชม และดาวน์โหลดได้อย่างเต็มรูปแบบ.
Register now to gain access to all of our features. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more. If you already have an account, login here - otherwise create an account for free today!
vxo circuit
Started by
surachit
, May 06 2022 03:40 AM
#1
Posted 06 May 2022 - 03:40 AM
#2
Posted 06 May 2022 - 03:42 AM
Harmonic VXO
Greetings:
I needed a quick, very temperature + frequency stable oscillator @ 50.8 MHz to test a receive mixer. Already running elsewhere on my bench, my main VHF signal generator wasn't an option.
Without going to a digital signal box, I weighed my build options:
Then came a mad search. Soon enough, I found a long forgotten bag of crystals and after 10 minutes of fumbling with it, I felt jubilant to find a 16.9344 MHz crystal! Good, I'll make a VXO with an output filter to help suppress all but the 3rd harmonic.
I grabbed a copper board and began soldering — no need for a schematic, for I've made many tens of xtal oscillators in my sleep. About 20 minutes later, I was done and ready to measure the ugly thing.
I needed a quick, very temperature + frequency stable oscillator @ 50.8 MHz to test a receive mixer. Already running elsewhere on my bench, my main VHF signal generator wasn't an option.
Without going to a digital signal box, I weighed my build options:
- VFO — difficult to stabilize at VHF.
- VCO — even more difficult to stabilize at VHF and it's too much work to make a PLL for it.
- Overtone crystal oscillator — little chance of finding a crystal to vibrate at 50.8 MHz.
- Fixed crystal oscillator — need a crystal to vibrate at exactly 50.8 MHz. Right!
- VXO — do I own a 10.16, 16.93 , 25.4 MHz etc. crystal ?
- VXCO — still need a crystal to double, or take a harmonic from. The varactor will add phase noise, but might work.
Then came a mad search. Soon enough, I found a long forgotten bag of crystals and after 10 minutes of fumbling with it, I felt jubilant to find a 16.9344 MHz crystal! Good, I'll make a VXO with an output filter to help suppress all but the 3rd harmonic.
I grabbed a copper board and began soldering — no need for a schematic, for I've made many tens of xtal oscillators in my sleep. About 20 minutes later, I was done and ready to measure the ugly thing.
Attached Files
0 user(s) are reading this topic
0 members, 0 guests, 0 anonymous users