Data sheet for FREQUENCY DEVICES 780RT-3 Band-Pass Filters?


Joined Jul 17, 2007
I believe the company website is here:
You might write to them and see if they would supply you with a datasheet. A search on their site comes up with nothing.
I found some of those devices on a surplus site, here: DEVICES - Active filter 20Hz-20KHz_ - 780RT-3/

I think that they are active band reject filters. The 780RT-2's look like they would reject from 2Hz to 2kHz. Looks like they may have had some extra provisions for rejecting 60Hz, 50Hz, and 2500Hz.

The 7th photo caught me off guard! LOL!

The AD524SD is an industrial rated part, but not mil spec; if it were, it would have /883B on the end. They are quite expensive though; a new one will set you back $56.76 at Avnet Express; $49 from Newark and Digikey, $47.43 from Arrow.

The "box" and front panel were designed to fit in a standard 19" equipment rack. It was not designed to be used in an aircraft; if it were, the boards would have some sort of mechanism to ensure that they could not become unseated during a flight. Those white nylon things are just levers to assist a technician in board removal.

It's difficult to say what it's intended purpose was, but I find it curious that 50Hz and 60Hz are on trimmer pots in the one board you showed details of; I can only guess that it was a piece of test equipment that was designed to be usable worldwide - or at least where either 60Hz or 50Hz mains power were available.

That's another thing - were it to be used in an aircraft, 400Hz would have been on a pot as well; because aircraft use 115V 400Hz 3-phase and 28V DC.