@Mike5000 There are quite a few people active on Es'hail-2 / QO-100 with 28 MHz as IF. However, they use an 'inbetween transverter' to convert 28 MHz to either 144 MHz or (preferably) 432 MHz or other
frequencies.
Here you find a cheap 28/432 MHz transverter. Of course it is not 'top of the bill', but good enough for your purpose and/or to play with (for that little amount of money). You can interface this transverter to e.g. a SG-Labs transverter or Kuehne upconverter to produce the 2400 MHz uplink signal.
For the receiving end you can either use a RTL-stick (TCXO) and a PLL LNB, or upconvert the 739.5 MHz (10489.5 - 9750) to 2400 MHz (with another converter ; -) so you can use the receiving part of e.g. the SG-Labs transverter as well, or ... you can downconvert 739.5 MHz to 432 MHz with a home brew converter. Such a 'in between -in between-' converter can be very simple as it's only purpuse is to serve you 'in between'.
If this all is too complicated, then consider buying an all mode 70cm transceiver and save yourself the hassle ; -)
(however, it IS possible, like I said, several stations use the aboven mentioned setup succesfully).