Posts by David G0MRF

  • 23cm transverter for 1267-1269

    Small update on ESEO.
    The satellite is now at Vandenburg Air Force Base and is being integrated with the other passengers on the SSO-A platform, to be launched by Space-X.
    Current best guess is 19th November if there are no problems.

  • 23cm transverter for 1267-1269

    The satellite is now completed and ready to be shipped.

    No more changes are possible.

    I agree, possibly the micophone input will be filtered to prevent signals lower than 200 - 300Hz passing to the transmitter. But it may be worth trying as you only need a few percent CTCSS. - Hope it works for you.


    73


    David

  • 23cm transverter for 1267-1269

    Hi Thomas.

    For power budget reasons, it's important to either shut off the transmitter on ESEO when there is no one on the uplink, or change from transponder to telemetry, which uses less power. As L band is full of radar signals, we could not use 'squelch' based on signal level. The 67Hz detector is a very reliable way to trigger timers to control the transponder. Once a 67Hz tone is detected, the transponder is active. If the tone is lost, the transmitter continues for 20 seconds. In practice you may be able to have a QSO if only one person has CTCSS....but don't chat for more than 20 seconds...

  • 23cm transverter for 1267-1269

    Hi Ross

    It sounds like you have an interest in telemetry, but you also say working the satellites on 23cm. The picture to the left is ESEO (European Student Earth Orbiter). It will have an uplink on 1263.5MHz, so when you select the IF frequency on your transverter it may be worthwhile getting TX capability on 1267 and 1263. - Perhaps 70cm to 23cm as Fox and ESEO have 2m downlinks.
    Currently, it's at ESTEC in Holland, but hopefully will be on it's way to the launch site shortly. (The definition of shortly is always open to interpretation!)


    73 David G0MRF

  • Octagon Oslo PLL LNB with external Reference

    Hi all.

    FYI. I measured the warm up drift of a standard Octagon LNB and in 30 minutes it drifted 34kHz. - OK, after 20 mins it was probably 'usable'.

    After removing the 27MHz crystal and replacing it with a Conner Winfield TCXO the drift was down to 900Hz in 30 mins, with no drift (<50Hz) in the final 5 mins.


    It may be worth avoiding some of the Fox TCXOs as they have internal digital correction which causes the frequency to jump in steps of 100Hz + at a time.


    73 David G0MRF