Quote:
Originally Posted by David Dunlop
Hello Jack.
The Insulator you posted a picture of looks like a main set aerial base for a wireless set that is not a 19-Set or 22-Set. Possibly a No. 9 or No. 11 Set...but do not quote me.
David
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Not quite: the big insulator was originally Aerial Base No.3 for wireless trucks using the No.2 or No.3 set and Aerial Rods 'D' - as part of the 34-ft mast. Later on they were used on wireless trucks with serious high power transmitters (WS 12, 12HP, 33, ET4336, etc.) and the rubber insulator was not up to the job, so it was bypassed electrically with the four copper braid straps, and sat on a large mushroom-shaped ceramic insulator (Insulator, W/T, 'H') so that it could be fed from underneath - the No.3 required a wire to the terminal on top of the insulator. The combination was redesignated Aerial Lead-in No.16.
Use with the whole 34-ft mast caused the rubber dome to collapse under the weight, so a "skeleton cone" support was made that was inverted over the rubber insulator and locked onto studs on the top plate, the rods were inserted and a screw clamped onto the bottom rod to take the load off the rubber. Static use only, of course - it was a rigid assembly.
The final version was Aerial Base No.20 which did away with all the Base No.3 bits and simply had a rigid socket bolted through Insulator W/T 'H'.
Best regards,
Chris (G8KGS)