The Pacific model 38 used a spiral line of light to indicate the frequency. Two cabinet designs have been sighted, both quite conventional by the standards of their earlier Art Deco inspired cabinets.
The spiral line of light is generated by two aluminium discs, one with a spiral-shaped slot cut in it and the other with a large leaf-shaped opening with curved sides. They rotate independently of each other and in sync (but at different speeds) to the tuning gang in order to produce a line from the center out to a point that indicates the frequency.
Intermediate Frequency: 456kc/s
3-band (all-wave) chassis covering broadcast (550 - 1500kHz), Intermediate SW (2.1 - 6MHz) and SW (6 - 18MHz).
The chassis uses a unique spiral dial tuning system with an effective tuning distance of over 2 feet and fast / slow tuning to provide fine control of the frequency. The dial assembly consists of either a red-tinted spiral line of light or a red dot (depending on brand) that indicates the frequency on a novel trio of spirals for the three bands. The band selector slightly rotates the system so that the dot or the end of the line aligns with the correct band.
The spiral tuning system is complex, and unless its been restored it always seems to be broken on sets found today. Repairing and setting the dial up takes some patience and trial & error, and while there is indication in the model 38 service documentation that there was to be a service bulletin from RCNZ for the dial assy, it has never been sighted.
Repair of the dial plates often requires the plates to be separated (on a lathe is easiest), then the old and normally torn / unglued paper to be removed and a new piece made. The red cellophane is often damaged as well and will most likely need replacing.
Dial assembly split - new hand-cut black paper template shown top left
New paper and cellophane glued in place ready to reassemble
Dial plates rebuilt, showing operation
It appears like the original dials used chain, possibly to eliminate any chance of stretch and to ensure accuracy of the pointer - however nylon dial cord has been used successfully in recent repairs. The dial cord runs from the tab at the outside edge of the back of the plate around the pulley then around the central bakelite spiral pully (which should be free to spin on the shaft) 2½ times then to the arm on the wave-change switch which should be roughly 45º above horizontal from the shaft when switched to the middle band to give correct actuation - this will require experimentation. Ensure the dial cord sits in the right place on the central pully so it doesn't run off either end, and watch the spike that it seems to have - purpose unknown?
Dial cord and return spring shown in position
Dial assembly remounted and strung
Note use of an aligator clip to hold the cord in place while getting the length and position of the lever correct
Restoration of the dial assembly is a lengthy process, but well worth the effort.
General Construction Notes for Radio Corporation of New Zealand Ltd: The first digit of the serial number typically indicates the year of manufacture of RCNZ chassis' (although not the decade - that requires a little knowledge of the valves, construction, etc). Sets from around 1934 onwards were often (but not always) constructed in a distinctive pressed 'baking pan' style chassis, seemingly unique to RCNZ.
|1937||Columbus model 38|
|1937||Stella model 38|
|1937||Pacific model 38 - this set|
|1937||Courtenay model 38|