On 3/4/2025 2:36 PM, Mike via groups.io wrote:
Instead of crystals you might consider a GPSDO like this one. A friend recently used a single output version on his 2m repeater receiver which I think is a Kendecom and its working great and really on frequency. The dual output version will handle a separate transmitter and receiver. I believe he just adjusted levels and plugged into the crystal socket.
+11dBm output is no stingy signal at 12.6 mW into 50 ohms. ? It's too bad these can't be directly FM modulated, because you could likely avoid the multiplier sections of a common crystal exciter / transmitter and feed the latter amplifier stages or build some other IPA to drive the PA.? Doing so would result in better phase noise specifications because the noise wouldn't be multiplied along with the frequency.
The specification show that these oscillators are as spectrally pure as a crystal oscillator - within a dB.? So - even if you have to use a phase modulator / multiplier exciter to actually have FM (PM), it's no worse than a crystal where spectral purity is concerned, it's much more frequency stable, and it can be 'programmed' to any reasonable frequency with tiny granularity that achieves a carrier frequency out to one cycle increments.
Neat stuff.
Kevin
Kevin Custer