If you happened to get one of those $7 SDR radio dongles from ebay and need to put it to work... here's one thing I tried...

Tune in with the R820T... (Using HDSDR)

This is both radios running on one channel.  They are out of tune enough that the channels don't even overlap!

Now I switch them into beacon mode and tune to 925.000 MHz...

Now I tune them up by adjusting the EZRADIOPRO_OSC_CAP_VALUE to get this...

Through the magic of special effects, I can overlay them...

Below are the before and after pics of normal transmissions (non-beacon mode)...

Settings used...

Here are the actual results I measured (warming up and final calibration)...

Ground = +7.3 khz @ OV 204 (cold)
Ground = +6.5 khz @ OV 204 (warm)
Ground = +6.1 khz @ OV 204 (hot)
Ground = +0.1 khz @ OV 208 (warm)

Air = -6.5 khz @ OV 204 (cold)
Air = -6.2 khz @ OV 204 (warm)
Air = -7.1 khz @ OV 204 (warmer)
Air = +0.6 khz @ OV 199 (warmerer)

All the pictures in this post are to the same scale.  The FSK signals (wider pictures) are on a different frequency than the beacon signals.

Make any predictions on expected range improvement below...