I've just got two temp controlled AWA Type 2R3535 temperature controlled piezo electric crystal units, Serial No.12/54YK that interestingly have the broadcast frequencies for 3AW and 3XY, pre-Nov 1978 - ie. 1280kc/s and 1420kc/s.

These have impressive internal construction with a fairly large custom copper inner tube, with an indent for a large glass Edison S1.1A thermal switch (64C for one unit), and thick copper base and a copper top cap. The crystal assembly is mounted internal to the thick copper tube, with direct leads through the base to the 7-pin octal base. The outer surface of the tube has two 6 ohm resistance wire windings, and it looks like one is switched by the thermal switch. The outer covering is typical AWA mottled grey-black coating.

Any insight as to applications for these units other than related to the broadcast of those two radio stations? I'm guessing the stability of these units would have been sufficient for actual broadcast use?

The 3AW unit has a 'rework' sticker dated 12/78 by Bright Star, which sort of aligns with the 29 Nov 1978 roll-over date - but I guess as a backup role.

Ciao, Tim

Info on the application of this crystal is provided in AWA Transmitter BTM-P5 manual from 1960's. The final operating frequency had a +/-5c/s tolerance spec.

https://bh.hallikainen.org/uploads/PeterSmerdon/AWA%20BTM%20P5%20500W%20Tx%20Manual.pdf
https://dalmura.com.au/static/AWA%202R3535.jpg