Re: [time-nuts] Picked up the Austral 2200A tonight
A lack of precision in that last email from me it seems. I was planning on using a DDS and re-purposed multiplier board to provide the 1.5Ghz LO, but as the time server needs to use the 10MHz signal to compensate for phase shift this won't necessarily work out as you have indicated.The multiplier board I have _should_ work using a 500Mhz input and tuning the pass filter to the third harmonic while maintaining a sufficient drive for the mixer. Your right on the DDS resolution and lack of reference, I may scrap that plan have to look at a 10Mhz referenced PLL for the input frequency instead. I haven't gotten to the IF filter yet :/ I have to admit a certain temptation to simply pull the rubidium and put it in a box or repurpose the existing box. It would be a shame to waste such a nice piece of obsolete tech though. I have noted a number of blown caps on the voltage regulator board so some repair work needed there. I can not fund the battery backup yet for the configuration settings.. Either its hidden, missing, or I'm having a stupid moment I was under the impression that none of these units were Y2K compliant, however this unit happy accepts dates post Y2K. I can't comment on the GPS rollovers though. Cheers J. Thanks for the help. Cheers Jason. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Picked up the Austral 2200A tonight
Jason If you build a single conversion front end as you suggest, then the LO will be 1500 MHz and low side injection causing a 180 degree phase flip. Hopefully not a real issue. The thing I ran into when I built my solution is that front end LO had to be locked to the 10 Mhz out of the Austron. The Austron directed the LO to establish a stable phase relationship through the receive chain. So the DDS master clock should in some way be controlled by the Austron 10 MHz. A thought would be 6 X 10 MHz filter it and drive the DDS. Now the funny thing about a DDS is that they don't often run atthe exact frequency you need. Always a bit high or low unless the math is worked out ahead of time. That drift will make the austron reference drift as it tries to correct it. (Null it out) With a single conversion process the IF filter will be a bit complex. It has to be several MHz wide and 75.42 is the center frequency. Then you may need some IF gain perhaps 10 DB as a pure guess. There is no pps or 10 MHz out of the unit till locked. However if you go to the output board the 10 MHz is there and goes to a gate that you can force to always provide the 10 MHz. I do not recall if I marked that down or not. Regards Paul WB8TSL On Mon, Jul 27, 2015 at 5:56 AM, Jason Ball ja...@ball.net wrote: Just picked it up, it has an internal rubidium which piqued my interest as worst case I could cannibalize the unit. It's also been sitting on a shelf for 10 years so the oscillator should hopefully have some life left in it. What does surprise me is the firmware is dated 25th August 1998, I was of the opinion these units weren't Y2K compliant and would have assumed an update in 1998 would have been tested... gps rollover not withstanding. Is there anyway to get the 10MHz output running off the rubidium without a satellite lock ? I can't seem to trigger it just yet. My plan is to use a DDS to generate a 1.Ghz LO and to feed this into a suitable mixer to down convert to the 75.42Mhz input signal for the gps reference as a start to see if I can get the thing working, allowing for the 1024 week offset of course. Just waiting on parts at the moment. Cheers J. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Picked up the Austral 2200A tonight
Just picked it up, it has an internal rubidium which piqued my interest as worst case I could cannibalize the unit. It's also been sitting on a shelf for 10 years so the oscillator should hopefully have some life left in it. What does surprise me is the firmware is dated 25th August 1998, I was of the opinion these units weren't Y2K compliant and would have assumed an update in 1998 would have been tested... gps rollover not withstanding. Is there anyway to get the 10MHz output running off the rubidium without a satellite lock ? I can't seem to trigger it just yet. My plan is to use a DDS to generate a 1.Ghz LO and to feed this into a suitable mixer to down convert to the 75.42Mhz input signal for the gps reference as a start to see if I can get the thing working, allowing for the 1024 week offset of course. Just waiting on parts at the moment. Cheers J. -- -- Teach your kids Science, or somebody else will :/ ja...@ball.net vk2...@google.com vk2f...@google.com callsign: vk2vjb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
