Other radios based on the same chassis:
6-valve plus magic eye tuning, bandspread radio
Intermediate Frequency: 455 Kc/s
Frequency Bands: 5
Chassis Notes(most schematics can be clicked to download a full size version)
Service information Philips-BZ737A-6V-AW-AC.pdf
General Construction Notes for Philips Electrical Industries of N.Z. Ltd:
Philips early-mid century were probably the Google of their time - they had branches in many countries and a global brand that everyone knew - and were apparently happy to let engineers come up with new ideas and implement them. Construction is often overly complex but very well engineered - although repairs can also take a complex path. They used time-in-motion studies to find the most cost effective way to asemble sets and sometimes this means repairs can be nightmarish (if you've ever worked on a V7A Theaterette this will be all too aparent). U suffix model numbers are transformerless (hot chassis) sets and great care should be taken, or the sets avoided altogether.
Philips model codes are complex - they are explained in-depth on the Philips brand page.
Mullard codes: The model codes from Mullard sets (unlike their Philips counterparts) appear to contain valve count and date information. For example, the model 525 is a 5-valve 1945 design. The 2 appears to just be an identifier (most likely in case there were two models in 1945 with 5 valves, which there was - the 515 is the small 'Meteor' mantle set).
Fleetwood codes are often just a rearranged version of the Philips code. For example, the FL374T transistor radio is a rearrangement of the Philips model L3Z74T. Early Fleetwood codes were numeric with F on the end. From about 1959 onwards the codes were much more like their Philips counterparts. They start with F or FL (or sometimes FZ for larger consoles)... These later codes also tend to end in a Philips-style identifier for the power source (A for mains, B for battery, T for transistor battery, etc - see the Philips brand page for more info on that).