[Arran]

Not only would it not make sense for a suppressor grid to be tied to the (signal) grid, but both would be tied to ground in this case killing the input from the previous IF transformer. Maybe there is a circuit out there that makes use of the suppressor grid for something other then eliminating secondary emission, but it's probably in some one tube home brew project. I did run into a similar wiring error in a Phonola though, they tied the suppressor grid to chassis ground whilst the cathode was floating above ground, and this was a wiring error from the factory. I'm not sure what difference this would have made to the performance of the 6K7 IF amplifier tube, but there was evidence that the tube had been changed most recently in the 1970s since it had the RCA block letter logo on it.
Regards
Arran