(The following is a transcript of a talk given by Ces to the Papakura Radio Club in 2001)
For this history of the ZC1 I am relying totally on 60 year old memories, so bear with me, but by and large I think it is fairly accurate.
I started work with Radio (1936) Ltd., the only factory that manufactured the ZC1. The ancient four-storeyed building on Quay Street, Auckland, wasn't really designed for radio manufacturing and it was a crowded place. Our big precision lathes and power presses were located on the ground floor, which also housed a large plating department, and the dispatch and inward goods department.
The first floor was mostly given over to administration. The second floor dealt with domestic, industrial, and commercial electrical goods, trading under the brand name 'Ultimate'
. The third floor housed the machine shop with its power presses, guillotines, welding and spray painting equipment, coil and transformer winding equipment. It was an extensive department and catered for the entire factory.
However it is the fourth floor, the radio floor, that is of interest here. Six or seven design staff were permanently employed there, headed by R.J.Orbell under whose guidance this team turned out solid equipment. The "wiring line" produced domestic radios and other equipment. When I arrived there it consisted of 18 to 22 people operating on an assembly-line basis. From here the radio moved on to the test department, where the alignment and functions of the unit were checked.
Around 1940 the Government declared many of the materials required for radio production "essential" (due to the war effort) and domestic production ground to a halt. It became extremely difficult to purchase a new radio. However one section still produced amplifiers and communication equipment for schools, factories, hospitals and, of course, military camps. Later on, towards the end of 1940, military people began visiting the design department and rumours arose that something was afoot.
The Canadian WS19 set appeared on the designer's bench and we were told that a local version of this unit was to be produced for the New Zealand forces. Two or three of our staff and some from other factories were despatched immediately to the United Kingdom and a team from our factory flew all the way in a Douglas DC3, a tumultuous, lengthy flight. After four or five months they returned and commenced work on the Mk-1. It was not easy to produce because many other manufacturers were brought into the project and perhaps this was the first time in New Zealand radio manufacturing that subassemblies were mooted so that different factories could produce particular units. It proved to be an excellent system.
Thus the first ZC1 prototype emerged. It was extremely robust; you could drop them from a height and they would still operate. I've seen some that were quite badly damaged and still operating fine. There were remote controls that went with the ZC1. Also, and this was continued later with domestic receivers, subassemblies were produced and mounted. A lot of work went into progressing from the prototype to the final manufacturing process. Every screw, every length of wire and every component had to be known. More than a dozen prototypes were produced, and in each case every component had to be detailed meticulously.
Many other companies were involved. People like Alex Harveys, who had never seen a radio in their life, did the heavy metalwork; photoengravers dealt with the screen printing; Akrad Radio produced the coils and RF chokes; Radio Corp produced the condensers and resistors (perhaps the first time this was done in New Zealand?); Swan designed the headphones and microphones. The supply of batteries was enormous and Erg supplied most of the batteries for the Services.
Power supplies and dial units were made separately, arriving at the factory in quantity and assembled further down the wiring line. Special care had to be taken here as the units were cadmium-plated and marked horribly by finger sweat so special cradles were made to avoid this problem; the units remained in the cradles until they were ready for final delivery. More staff were taken on for the wiring line. All the wire was pre-cut and tinned, for which a special department was needed. When the ZC1 first went into production we aimed at thirty to thirty-five sets per day. There were many missed deliveries in the early days. Sometimes the dial units didn't arrive, sometimes it was the power supplies. Often sets were still going down the production line, but were stored up in huge tiers because of a lack in certain components.
Still, we had to maintain our production level. The Defence Department stipulated a definite number of units per month in the contract. The early ZC1's had watch cases, old Westclox pocket watch cases, but they disappeared so quickly that this idea was dropped. There was not very much in the way of cosmetic changes to the face of the ZC1. Apart from the disappearance of the watch case from the Mk-1 and the alteration of one or two switches, hardly anything was altered from the original design.
Antennas had to be made and wooden boxes for the spare valves. Australia came into the scene and AWA Radiotron™ began producing the valves required; 6X5's in the earlier versions, the 6U7's, 6K8's, and 6V6's. The quality was not the best and it became necessary to pre-test virtually everything (in a dynamic circuit) before it went on the production line, so we created a pre-test department for the task. I remember oil drums full of broken valves, thousands and thousands of them, that didn't meet the requirements. Vibrators and meters also proved to be unreliable.
About this time the Department of Scientific and Industrial Research (DSIR) set up their own laboratory in our building. Many of our staff (secretively) were utilised by the DSIR for building prototypes of radar equipment. Strict security was insisted upon in the war years; nothing was ever discussed outside the factory.
In addition orders were coming through for lots of other stuff, such as VHF equipment, perhaps the first venture into that, including little transceivers for the tug boats around the Hauraki Gulf. Some remote controls for the lights around Auckland Harbour were also produced. Changes were made to some of the flying boats that arrived here with UK equipment and most of them serving in the Pacific had to be changed over to American style Bendix equipment.
At the same time Seagar Bros. and Mason Bros. started to produce 110 ft trawlers for the American service in the Pacific. These required radio equipment to be designed, made, and installed. Fairmiles were being made and they also required radios. In general there was a large variety of design and production going on this floor that was originally designed just for plain old four valve to ten valve domestic receivers. Materials were in short supply and we were low priority for materials from the USA and UK. However, through the help of local manufacturers and by the good graces of one or two American companies we still continued to get materials for the ZC1.
After a year and a half the military reported back that there were problems with some of the units in the Pacific. They were growing mould and fungus inside them. We redesigned the plating and spray painting to tropic-proof them all. That meant changing wiring, solder (fluxes were out because they grew fungus), and utilising special paints over the sockets and wiring. They had to be mechanically robust as well as electrically satisfactory. (When they changed the solder, they also had to change the soldering irons because they required more heat. I remember the little soldering iron boxes built of fire brick and elements, you pushed the soldering iron in, it didn't have a cord on it.)
Anybody that has tried to service a ZC1 knows how difficult it is to remove the wires from the terminals but military specifications demanded that it be done like that. The life expectancy of a ZC1 in service was only eighteen months. That they are still operating is incredible, and I'm sure the people involved in the original design would never have believed it.
The ZC1 needed both CW and AM phone communication. They had to have some means of pre-setting frequencies so that a whole unit could be sent out, all operating on the same frequency, and yet able to alter the frequency readily. The power output needed to be adjustable since the power required for communication had to be minimal, especially in the North Africa section and the Pacific. The enemy was very good at DF'ing and could locate an operating transmitter very quickly.
To give you an idea of how little signal was required for DF'ing, we at Marconi were getting requests from the ships to quieten the receiver oscillators because submarines were DF'ing on the receiver oscillator. At sea, with sensitive equipment, you could pick up that oscillator in the receiver; very little power could create a problem.
By the time the Mk-2 (1943) came out production was progressing smoothly at a cost of about £NZ 450 a piece (about $40 000 today). Most of the out-manufacturers doing the subassemblies had improved and the materials were arriving with fair regularity.
Later on I entered the final test department with a Ministry of Defence Army sergeant supervising me. I had to test each unit (using dummy loads and other tools) for performance in receiving and transmitting, on all frequencies. After a successful test they became the possession of the Army.
Now for a quick review of some of the more frequent problems I encountered.
The dial units were not always smooth in operation, and the machining of them wasn't always the best. We whipped them out and had them machined locally. Sometimes vibrators didn't start, although they'd been working through the pre-test department. Valves often arced over, the old 6X5 in particular would short over between cathode and filament. There was a general downgrading of expectancies when the components began to arrive. For instance, we had been used to the American Bradley relay; a lovely, silver-plated unit, and the relays that arrived looked cumbersome by comparison. But we had to use local materials. How many units did we turn out? Somewhere between 20,000 and 25,000, I suppose. Production continued until the end of the Pacific war, but there must have been thousands stored away that never went into service. Some of them were sold off eventually to other countries. Apparently a Mk-3 was in the initial stages of design, but (happily) the war finished before production could commence.
HF radio activity during the war was all military, lots of propaganda stations and lots of interference. Every staff member that enlisted was guaranteed a job when they came home. The firm did a lot of work with food parcels and other things for those people who were overseas.