• Hi,

    if you use 24MHz, you will find the center of the downlink passband on 10489.750-(24*390)= 1129.750 .

    If you use 25MHz, you will find the center of the downlink passband on 10489.750-(25*390)= 739.750.

    The 24MHz reference lets you receive the DATV transponder on a normal unmodified Sat-RX ; you can receive the beacon and some other individual signals.

    The 25MHz reference does not allow that, because sat-RXes do not cover 740MHz.

    If you want to receive with a normal 432MHz rx , you use a reference in the range of 25,78xxxMHz

    Some even receive directly on 2m band.

    If you use a rtl-stick or other sdr device for rx, it is not important, what reference you use, as long as the device can receive the resulting frequency.

    Identify the built-in crystal by checking the LO frequency printed on the plastic cover, 9750 means it is 25MHz.

    25*390=9750 , but it will also work with 24.xxx or 25.78xxx MHz.

    Edit: The description for the lnb from the link you provided says 9.75GHz. Voila'

    73, Martin

  • Thanks for explaining that Martin, very helpful.

    I have options for receiving. I can use an Afedri SDR-VHF so can directly receive wherever the IF appears, I have to lock the Afedri to 80MHz but I have done this with a Perseus RX so I do not expect problems . However most likely I will use my ANAN-100D in duplex mode. This means I will need to convert from the IF to 28MHz.

    On TX I have made a 144>2400 upconverter from parts I already had, it works beautifully at up to 18W PEP with 3rd orders at -42dBc. PN is much better than needed. Also in the path is HA1YA 144/28 XVTR, a 116 MHz Kune XO locked to 10MHz, For TX I have a 7dBm mixer, 2256MHz LO, SAW filter, UTMS PA and one of those nice Band pass filters from Poland. LO leakage is -78dBc, IF leakage better than I can easily measure (>100dBc). I expect to use a lot less power than 18W with a Triax 1.1m dish. Of course it still needs boxing up. I will need 6m of coax. Hopefully I will be QRV in a 2-3 weeks.


    Conrad PA5Y