IC746 now locked to GPS disciplined oscillator

1 post / 0 new
G0MOH
Offline
Last seen: 1 year 3 months ago
Joined: 2009/10/09 - 04:27
IC746 now locked to GPS disciplined oscillator

I had quite bad drift at various times with my IC746, mainly when the shack got hot (40'C is not uncommon here in the summer, indoors). I tried the cotton wool in the LO cavity trick, which seemed to help a bit. Not helped of course by the PA fan running up on Tx.

However, I have now got a Trimble Thunderbolt 10MHz GPS disciplined oscillator running, which feeds into a G4HUP tripler to generate 30MHz. This 5.5dBm 30MHz signal is then injected into the rig's LO coil to lock the LO at a stable 30MHz.

All WSPR reports now are zero drift, and testing on listening to beacons is accurate to within fractions of a milliHz, right from switch-on! No more drift!

73 - Rob VK2GOM / G0MOH