Okay so that device (that we were thinking was a diode) is spark gap device and it is to protect from lighting. Understood.
Now, whether it is currently connected in the circuit or not doesn't make any difference. (it is currently disconnected).
I still get continuity (15.6 ohms) across the antenna terminals. Is this supposed to happen?
If yes, do I have to now disconnect the tuner, open it and check the same?