I rebuild a Inverto 410 Prem from the 25.000MHz Quarz to a TCXO Oscillator with 1.5ppm at 1.8V or 0.2ppm at 3.3V Supply. In the pictures is a Inverto Quad 410 PREM and will be rebuild with 3times out and 1 F-Connector is for the input for a external Oscillator with a TCXO (temperature compensated X Oscillator). This is made for a much stability Oscillator to receive very small signals like the SSB(US
signals from the 26°East Satellite that is used from the HAM-Radio operators. There signals are only 2.4kHz USB small and are between 10.489500GHz - 10.490000GHz. Well you can receive with a Inverto 410 Series Single/Duo/Quad/Quattro this low signal under 10.7GHz.
The PLL is a multiplier from 390*25MHz= 9750MHz(LO-low) If we would like to receive the signals from the HAM-operators so we receive it at 10.489500GHz - 9750MHz(LO-low) = 739.5MHz. This is tunable with a USB-SDR-Stick for around €50,- and a Computer will decode the signal via IQ-demodulation. Left Picture the Oscillation (higher signal yellow sinus) from the Quarz is high that mean this is the Amplifier output (no Entry).
Right Oscilloscope (lower signal yellow sinus) from the Quarz is lower then the other this is the input for the external 25MHz TCXO. I build out the Quarz and connect it to the right side of the QUAD (don't do that at the single there is it on the other side). First measure then connect. A DC decoupling with a 560pF Cap will isollated it from the PLL and the external TCXO. Then your LO will be much stable and you can receive signals like the from the 26°East.