[TenTec] Omni VI TCXO instructions

[Peter Bertini]

This question would be easier to answer if we knew what kind of TCXO you
have.

Ten Tec used a 5-volt TCXO that was designed to drive TTL digital levels.

Most modern TCXO devices are now designed for 3.3 VDC systems. Some are
spec'ed for driving TTL.

There are also some *linear* oscillators on eBay which operate on 5 volts,
but they will not drive a TTL load.

Ten Tec injected their replacement TCXO on the emitter of Q2.  They also
lifted on lead on R2, 150 ohm resistor, to kill the original 20 MHz
oscillator.

Or...

If your TCXO will not drive TTL,  inject the signal on the base of Q1
through a .01 uF disc cap.  I'd also suggest removing the  C7, a 150 pF cap
between the base and emitter... that will increase drive level. Remove the
original crystal, and leave the 150 ohm resistor.

I have used both methods.  I recently bought a batch of RTX0230 proprietary
TCXO devices on eBay. They only output around 1 volt peak, but they will
drive the original Ten Tec oscillator stages when they are used as buffer
stages to interface  to TTL levels.

Pete K1ZJH