I managed to get Rick's HS748 into FSX. 1 issue radio's.
Up here in the Arctic many of our simmers are FSX Gold but lack speedy internet and I have received many calls and e-mails for help with this wonderful aircraft in relation to the radio's. This HS748 is still in service up here and is part of our life line. Any help would be greatly appreciated not only by me but also our small FSX community up here.
Just installed (hs748v1f.zip and 748fix.zip) in FSX-SP2 so haven't done a full checkout but....
(Edited 11/08-19:20Z) The radios, along with AP and some gauges/instruments, operate off the 115V AC Bus so make sure the Inverters are on. (in your image, just right of ADF1, it appears the 'failure' lamps for the Inverter (and Alternator) are lit indicating an off or failed state.)
I found that if you are inheriting elec system states from another aircraft you may have to cycle gen switches (off/start/on) for the system states to set properly.
As one of the original Beta testers for Ricks 748 - the first thing I saw was the same as Dave the Alternator fail light....
Tim - follow the checklist that Fraser made for the cockpit and you wont go wrong - like ALL of his cockpits the Viscount, Vanguard, Argosy and soon the Britannia and CL44 --- They are very in depth and true to life -- as I said obviously you hadnt tripped the alternators on the 200v AV panel from "run" to "start" - they are on a spring switch and momentarily holding them in the start position will power both systems and give you 115 bus as Dave said --
I would NOT try and "fix" Frasers panel - as this will result in worse problems - just RTFM and follow the checklist and all will be well -- Now you want to talk about fuel heat and fuel trimmers?