Hi All

There has been some digital activity today on Oscar 100.

I had to change uplink LO yesterday to a non-locked crystal controlled source, which has some small drift. This is making it impossible for me to use narrow tone spacing modes such as FT8 and JT65A. During a QSO with OZ1CTZ we were struggling with him decoding me on JT65A and he switched to JT65C after which the QSO proceeded perfectly.

My drift problem on transmit is probably similar to that which would be experienced by unlocked Octagon users, so choosing a digi mode that is more immune to drift seems desirable.

I did some testing here earlier using the Goonhilly SDR to feed audio to WSJT-X on a second PC and found also that JT9F (Fast) works extremely well with 100% reliable decoding. I've been testing with 10s periods mainly, but 5s also works. With these faster modes, drift will have less effect.

JT9F is available in WSJT-X and needs to be run with VHF and up features enabled to access the 'Fast' checkbox.

For JT65 users, I would recommend WSJT-X v2 over earlier releases, as the JT65 decoder was improved recently to cope with larger drift rates.

If anyone is interested in trying this out, pse PM me and would be very happy to try it.

73

Charlie G3WDG