[russell_w_b]

Originally Posted by bigus01

Resistance between T1 & T5 - 22 ohms

This seems rather low. Even, with the phone 'off hook' and the 35 Ohm ASTIC winding shunted with the 1000 Ohm bell-coils in series with both non-inductive 30 Ohm windings and the 30 Ohm ASTIC winding will only give about 34 Ohms.

Could you repeat this measurement T1 dial strip to T5 telephone block with the phone 'on-hook', please?

Originally Posted by bigus01

Resistance between green & red - 50 ohms

This seems low, so you must have one of the lower-resistance mic inserts: probably the one original to the 184 handset. The 164 handsets usually have a mic in that measures kilohms. It doesn't matter too much.

Originally Posted by bigus01

Resistance between green & white 45 ohms

Sounds about right for a receiver 2P - one with the flat front once you've slid the diaphragm off.

Originally Posted by bigus01

There are no terminal markings visible on the coil. I do have another phone on an extension, which, if disconnected does drop the voltage slightly. Also connected are broadband router and Sky box.

Wonder if there's something in either of these units that shunts the bell capacitor in the master LJU (main socket)? I wouldn't've thought so, mind. The terminals on the coil are tiny and a magnifying glass and good light helps!