ZLW Remembered

ZLW Transmitter building 1912ZLW Transmitter building 1912ZLW Transmitter building 2006ZLW receiving office building 1943

A brief tour of ZLW Wellington Radio as we knew it and as it is now. This is the work of three technicians, who worked at the station in the late 1950s and early 1960s, an ex Telecom electrician and a daughter of one of the technicians.

The pictures above, starting from the left hand side: opening day in 1912; the transmitter building in 1912; the transmitter building taken in November 2006 and looking down at the Receiving Office taken in 1943.

The bottom row of pictures, starting from the left hand side: a Canadian Marconi radio receiver model CSR5; an aerial photograph of the transmitter building in 2006; a view of Wellington city from ZLW and looking up the access road one corner before reaching the transmitter building, the photograph taken in November 2006.

The technicians are Brian Gallagher ZL2ADY, Warwick Purser VK4NN (was ZL2AMK) and Jamie Pye ZL2NN.
The ex Telecom electrician is Jim Pye ZL2PU, son of Jamie Pye.
Elsa Kelly is daughter of Jamie Pye, who with assistance of her daughter Hannah, took all the 2006 pictures.
Back to top

Canadian Marconi receiverZLW Transmitter building 2006 from Google mapA view of Wellington CityA peek at the road in 2006

Please, let us know of additional information resources. Use this Contact us at e-mail link, replacing the words with the appropriate symbol and full stops.
Back to top

The Start
While doing research for my greater family tree, my daughter came across a Picture of me, Jamie Pye ZL2NN, taken in about 1960. This picture is shown as Picture 1. This picture was taken at Wellington Radio, ZLW, located on Tinakori Hill above Wellington City.

ZLW with ZL2NN at the DS12’s Sideband Exciter Unit
Picture 1: ZLW with ZL2NN at the DS12's Sideband Exciter Unit
Back to top

ZLW or Wellington Radio was part of a chain of coastal radio stations that existed from 1912 to 1996 in New Zealand. The chain of stations started with ZLD Auckland, ZLW Wellington Radio and finishing with ZLB Awarua Radio near Invercargill. The main purpose of these stations was ship to shore communications with messages from emergency to radio telephone conversations. Large ocean liners used Morse code transmissions using medium frequencies while small ships, like a four metre long runabout, used high frequencies for the transmission and reception of radio messages. Coast stations were not restricted to maritime radio services and did radio communications for Pacific Islands and radio links to other countries, mainly Australia, Britain and the United States.

The coastal radio stations were operated by the New Zealand Post Office and owned by the New Zealand Government.

About the same time as this picture was uncovered, I renewed my relationship with a previous worker at ZLW, Brian Gallagher ZL2ADY. Over the years I had kept in touch with Warwick Purser, VK4NN, who also worked with me at ZLW. Warwick is now residing on the Gold Coast in VK4. We got our thoughts together and produced a plan of the Transmitter Hall, the Receiving Office and a map of grounds ZLW, these are accessed as separate items from the main menu. My son Jim, ZL2PU, helped with the 1960s map as he was employed in the 1980’s as an Electrician for Telecom and did some work at ZLW.

Our job at ZLW was to keep the station working, both at the transmitting and receiving stations. We were employed as radio technicians, having a knowledge of how radio transmitters and receivers worked and how to get them going should they fail to operate. Another function was to operate the transmitter station. This involved changing antennas, changing the frequencies of the radio transmitters and recording all events in a written log book.
Back to top

Jamie Pye's Memories of ZLW
Giving some thought to Picture 1 and doing some research I found I was standing in front of the sideband exciter unit for a Standard Radio (STC) transmitter model DS12. The sideband exciter unit made the DS12 transmitter into a two–channel telephone transmitter using the upper and lower sideband respectively. All done by analogue methods, requiring a lot of careful alignment and care, as digital was just on the horizon in the early 1960's.

The DS12 transmitter is on my right hand side in Picture 1. The main use I can remember of the DS12 transmitter was for telephone calls to cruise ships around the South Pacific, particularly during Christmas. I only remember using the two–channels to transmit telephone calls once during a particular busy Christmas period.

What was used at the receiving end to sort out the voice channels I never found out?

I realise now that the use of ZLW was decreasing and the closure of the station was not far away as we were very busy when I started at ZLW in 1958–59 but the work had slowed down considerably when I left in 1961.

The antenna used at ZLW for the higher HF band was a bit suspect and had high standing waves. We got a lot of radio frequency energy back and the whole transmitter cabinet became radio frequency alive, when it was tuned above 16 MHz. Unlike an electric shock, radio frequency energy heats body parts when contact is made with a radio frequency source. To tune the transmitter you had to use metal parts that became hot to touch. A most uncomfortable feeling. I do remember using towels to insulate my hands from the tuning controls during a tune–up on an 18–MHz frequency. Thank goodness the transmitter was not used often on frequencies above 16 MHz.

Power Output of The DS12 Transmitter: Jamie Pye was told that the power output of the DS12 transmitter was 10 kW. Since doing this article and reading the specifications for the final amplifying valve, the 5J–180E, the power output value was reduced to 1 kW. A value of 5 kW has also been suggested. This value seem to be reasonable considering the physical size of transmitter.
Back to top

The Final Transmitting Valve in a DS12 Transmitter
The other interesting part of the DS12 transmitter I remember, was the final valve used. This was an external anode type with a type number of 5J–180E. It was air cooled by forced air being pumped through the fins of the external anode. The valve sat in what looked like a lavatory pan. Figure 2 shows the 5J–180E tube or valve.

Final Valve Used in The STC DS12 Transmitter
Picture 2: Final Valve Used in The STC DS12 Transmitter–A valve or tube with a part number of 5J–180E
Back to top

I did have the job of changing one of these valves, as we couldn’t get full power out one day. The valves were rated to last 5000 or so hours and I remember that the one I removed had done about 15 000 hours. The old valve was claimed as an ornament for home. It took pride of place by sitting on the TV set until son, Jim started to crawl. If he had pulled the valve over on to himself, it could have caused some serious injury to a small boy’s feet. The valve weighed in at about 5–7 kg (about 11–15 pounds) with all the copper used in the construction of the external anode. The size of the valve was 155 mm (about 6 inches) diameter an 245 mm (about 10  inches) high

You can buy one now for around $US200 in 2006.
Back to top

The DS12 Transmitter found again
About the time I resigned from ZLW and the Post Office in 1961, the ZLW DS12 transmitter was to be shifted to the then Post Office transmitting station at Himitangi.

Found Again; The STC DS12 Transmitter at the Foxton Museum
Picture 3: Found Again; The STC DS12 Transmitter at the Foxton Museum
Back to top

In 2004 I met socially a committee member of the Foxton Museum MAV Tech Audio Visual Museum and Theatre. The committee member told me all about the new “old” transmitter that they were getting from Himitangi Radio. Was this the DS12 transmitter ex ZLW? A discussion took place and it was revealed that this was the same transmitter. Joy, I was able to ask him to take some photos for me. Picture 3 is the photo taken by him of the DS12 transmitter with the step ladder resting on it and to the right is the sideband exciter unit my picture was taken with, that many years ago.
Back to top

Comparing the Relevant Parts of Picture 1 and Picture 3

Comparing the relevant parts of picture 1 and picture 3
Picture 4: Comparing the relevant parts of Picture 1 and Picture 3
Back to top

Picture 4 compares the relevant parts of Picture 1 and Picture 3. This shows that the unit in the Foxton Museum closely resembles the one taken in the 1960s with Jamie Pye standing in front. Jamie Pye knows that the pictures shows the same unit.

If you now look at Transmitter Hall Layout Around 1960 you will see at the bottom of Picture 1 ZLW Wellington Radio Transmitter Hall 1960s a red circle with an arrow. This is where Jamie was standing and the direction he was looking in, when the photograph was taken.
The BLUE circle on the same Picture 1 is where the photographer was standing when the photograph in Picture 5 below was taken.
Back to top

ZLW Transmitter Hall

ZLW Transmitter Hall in the 1950s
Picture 5: ZLW Transmitter Hall in the 1950‘s
Back to top

Referring back to Picture 1 again, if I turned around, I would have the sideband exciter unit at my back and see a scene like what is shown in Picture 5, that is, the Transmitter Hall of ZLW.

We have not been able to identify the person sitting at the table in Picture 5.
Back to top

ZLW Transmitter Hall Block Diagram
Picture 6: Part of ZLW Transmitter Hall Block Diagram
Back to top

Picture 6 identifies the transmitters shown in Picture 5 and starting at the top left hand corner we have:

  1. RCA type 351: This amplitude–modulated transmitter had parallel 813s as the final RF amplifying valves and beautifully made rotatable inductors as part of the tuning system. It had an internal amplitude modulator. The RCA transmitter was a very well made World War II navy type.
    At ZLW this transmitter was used for the weather stations at Raoul and Campbell Islands, to communicate every three hours with the Meteorological Office in Wellington, with weather reports.
    There is one thing I remember about these transmitters, is the time after a regular maintenance, I walked near one of them and noticed that it seemed physically hot. On closer inspection I found that I could not touch the cabinet with my bare hands without being burnt. Something was wrong here! I waited until the operator had finished with the weather messages and turned the transmitter off to cool down. No way could anything be touched on the transmitter until it had cooled down.
    It took about two hours to cool enough so the tuning and other controls could be touched. Turning the transmitter on again and a close inspection revealed that the final valves had their anodes glowing red. This was not the normal operating condition for this type of valve. It was found that the final valves were being used as doublers and so dissipating a lot more heat that was normal. A complete retune of the transmitter fixed the problem and the transmitter operation returned to normal.
    The point of mentioning this was to prove how robust these transmitters were as the transmitter continued to operate normally even after a gross overloading and heating had occurred to all its internal components.
  2. Mullard Oscilloscope: From memory this was a state of the art test instrument using a distributed amplifier using valves for vertical deflection and it also had dual beams.
  3. C & B 1 kW small ships 2162/2182 kHz: The Collier and Beale kilowatt was a common transmitter in New Zealand Coast Stations. The final transmitting valves were push–pull 833s, which in normal operation had anodes that glowed cherry red. They used a pi coupled output circuit that quite often would go out–of–tune if a moth or a huhu bug got caught in the final tuning capacitor. The 833 valves would light up like incandescent lamps until the cut–out disconnected the power. If the cut–out didn't work quick enough, the valves were often destroyed. This particular transmitter had its own internal amplitude–modulating amplifier.
    I had an opportunity to return to the station in the 1980s and this transmitter had been replaced with a solid–state 1.2–kilowatt output version. It operated in the single sideband mode with carrier, which could be received by an AM radio receiver. From memory the transmitter had 20 x 60 watt final transistors that could be hot swapped, that is, removed and replaced while the transmitter was in operation. The size of the solid–state transmitter was similar to the older valve version. There is no size saving with solid–state transmitters as the heat sinks used on the multiple output transistors were large and took up most of the space in the top half of the cabinet.
    This transmitter was used on the medium frequency small ships telephony frequencies of 2182 kHz (calling and emergency) and working 2162 kHz.
  4. C & B 100 W 2182 standby #131:
  5. C & B 100 W Portland Island:
  6. RCA type 351 standby:
  7. 300 W Redifon to Irangi: My memory of this transmitter is that it was the only one with a VFO, which was unique as all the other transmitters were crystal controlled.
  8. 1 kW at 1–ampere supply: No knowledge about this.
  9. Test Equipment and Jack Fields–Patch Panel: From this position you could key all transmitters together and feed audio signals to any telephony transmitter.
  10. Operator‘s desk and VHF monitoring control unit: From this position you could dial–up the VHF channels in use. Taxis and police are the ones I remember.
    Back to top

ZLW Receiving Office Layout 1960

With Story By Brian Gallagher December 2006
Busy and the noise. Upon entering the main operating room, one was struck by the busy atmosphere and the noise, the noise of Creed Teletypes, reperforating machines, morse code from the main marine 500 kHz room and voice traffic on the “Small Ships” coastal frequencies being monitored on a loud speaker. There was a strong sense of purpose in that room. The radio and telegraph operators were a cheerful friendly lot and there was sometimes time to swap a yarn, or for them to extract an answer to a technical enquiry from the technician visiting from the transmitting station to do the daily maintenance. Although the equipment was aged, most maintenance was light as faults were few and far between.
Back to top

Diagram of what we remember the layout was of the RO in 1960
Picture 7: ZLW Receiving Office Layout Around 1960
Back to top

Names like Marconi CSR5, National HRO, RCA AR77 and Redifon receivers with which the receiving office were equipped will be familiar to vintage enthusiasts. For this writer a quick morning maintenance visit included a spell on the AR77 in the equipment room stickybeaking to the regular morning AM Ham radio nets on 80 metres – just testing the receiver of course!!!
Back to top

Marconi CSR5 Receiver
Picture 8: Marconi CSR5 Receiver
Back to top

Monthly maintenance was more intense with performance tests on all receivers which almost always turned in a one microvolt performance. A simple valve change usually put things right if they didn’t make their normal performance standard.
Back to top

RCA AR77 Receiver
Picture 9: RCA AR77 Receiver
Back to top

In the equipment room tucked away in a corner, was a Murphy B40 communications receiver owned by the Navy and connected by line to Defence Headquarters in Wellington. At some time the B40 as a defence item had been on a restricted or secret list but in 1961 this had long since been declassified. The Station Superintendent apparently was unaware of this as great pains were taken to hide its presence from a group of radio officers visiting from a Russian ship berthed in Wellington. A cover was thrown over the receiver and the Russians were steered away from that part of the building. B40s at that time were being advertised for sale by the Government Surplus Stores in the UK magazine Wireless World
Back to top

National HRO Receiver
Picture 10: National HRO Receiver
Back to top

Running along the south side of the building was a seldom used technical work shop and an emergency power room. This room contained a large bank of lead–acid batteries providing a 24 volt DC supply. Nearby to this stood a nineteen inch equipment rack on which was mounted eight 24 volt DC to 230 volt AC rotary converters fed from the battery bank. In the event of a power failure, the rotary converters could be manually started and through knife switches switched over to power key items of equipment in the receiving office until the Caterpillar emergency generator up at the transmitters could be started.

This writer being a newly qualified and zealous technician, decided that in order to extend the life of the batteries and maintain their capacity would benefit by recycling ie. a full discharge and recharge. He then, early one morning, set all the rotary converters running off load so as not to disrupt station operation figuring that even in this condition the resulting drain would eventually discharge the batteries – and he was right, What he did not know or realise was that a fail safe relay which was constantly energised to hold in the setting off contacts in the station‘s fire alarm system received its operating voltage from the emergency battery supply which was being discharged by the rotary converters. Around four o‘clock in the afternoon the battery volts dropped low enough to release the relay in the fire alarm control system and set off the alarms. Reaction was swift. Within a few minutes the Northland fire brigade arrived, not an easy mission up the very steep hill road. Yours truly, rushing down the hill from the transmitter building, holding a large screw driver in his hand, was greeted by the Fire Chief who said, “You better put that screw driver away lad before you cause any more trouble.” And I was deflated. Realisation set in and I quickly rushed into the emergency power room, quickly turned on the battery charger and turned off the rotary converters.

Many memories and stories can abound from those days at the RO, but sadly that is all there is now, those and a flat bare clay patch where the RO once stood.
Back to top

The Standby Power Generator

Warwick Purser VK4NN Remembers Powering the Suburb of Northland
Warwick Purser remembers the standby generator was a D8 Tractor motor giving out about 100 kW. To start the D8 you had to first start a small two cylinder petrol motor and wait for the D8 to heat up from its exhaust...Warwick continues

I remembered the other day that Jack Coleman was connected with an incident involving the ZLW backup generator, whether this is truth or myth I don’t know, the story goes that he did a regular run–up check of the system – which wasn’t allowed by us mere mortals – however, the output of the generator was somehow fed back into the grid! Northland was helped by ZLW but unfortunately stuffed the large diesel motor...
Thank you Warwick – ZL2NN
Added 1 January 2007

Jamie Pye comments
The story is true, however, I don’t remember when it happened but I do know the fix. You had to slide a large metal bar across when switching off the mains power and turning on the standby power. To change the station from standby power to mains power you had to turn off the standby power then slide the bar back and then turn the mains power switch back on. The mains and standby switches were large. Capable of 50–100 amperes or greater. The generator was also stuffed.
Back to top

Graeme Bramwell ZL1GBB Continues the Story
Now, I was actually there when this happened. I was on the 4pm shift and had been down in to Wellington. There had been a power cut and most of Wellington had been blacked out. I was aware that was happening so I was most surprised when I noticed street lights on at the bottom of the hill. I went up to the transmitting station and asked about it. The shift technician at the time suddenly looked most perturbed when I asked and raced out to check the switch. Sure enough, both switches were on, so the diesel was powering the whole adjacent suburb. A rapid withdrawal of the offending switch fixed that problem and the Diesel was noticeably relieved.

The diesel was a 100hp Caterpillar mounted on skids. It was a pig of a thing and many times would refuse to start. Mounted on the side was a small two cylinder petrol motor, which was started by an electric starter. The exhaust was used to preheat the diesel. After allowing sufficient time for pre–heat, a dog clutch was thrown in and the motor would turn over. Problem was that every so often the clutch would be stripped before the diesel would fire. Not very good when you were relying on the thing for standby. It never was designed for standby use, unlike the new Dorman diesel that was installed at Makara while I was there. It was all electrically heated and could be started and on line in 40 seconds. Sheer luxury after the ZLW diesel.
Thank you Graeme – ZL2NN
Added 6 January 2007

Explanation of the use of the safety slider
Below is a representation of changing the radio station from mains power to standby power using . The slider was installed after the incident of feeding power back down the mains using the ZLW standby motor generator. If you look at the first picture below where the station is on mains power, you will see that the standby switch is blocked from being turned on by the safety slider. To move the safety slider both the standby and main switches need to be in the off, or up position, as shown in the top right hand picture below.
Back to top

Station on mains power
Picture 11: The safety slider that allows only one power switch on at a time is coloured blue. The orange circle being the handle that allows the safety slide to be moved. The station is on mains power with the MAINS power switch in the down position and showing red. The ST’BY switch is locked and cannot be moved because of the presents of the safety slider
Back to top

Power off and ready to change power source
Picture 12: To change the station to ST’BY power after the standby generator has been started. First the MAINS power switch is turned to off. This allows the blue slider to be moved to the left using the orange handle.
Back to top

The safety slider can now be moved
Picture 13: The safety slider is moved to the left freeing the ST’BY power switch
Back to top

The station is now on standby power
Picture 14: The ST’BY power switch is turned to on shown by the red of the switch. The station is now on standby power
Back to top

Transmitter Building and Hall From 1912 to 2006

ZLW External Transmitter Hall 1912

ZLW Transmitter building 1912
Picture 15: External of the transmitter building in 1912
Back to top

ZLW Transmitter building 1912
Picture 16: Transmitter building in 1912 is one building with a front entrance in centre of East facing wall
Back to top

ZLW Internal Transmitter Hall Layout 1960

ZLW Transmitter Hall Layout Around 1960
Picture 17: ZLW Transmitter Hall Layout Around 1960
Back to top

1. The PINK circle in Picture 17 above, represents the person sitting in the chair in Picture 5 of ZLW Remembered
2. The BLUE circle in Picture 17 above, is the approximate position of the photographer to take Picture 5 in ZLW Remembered
3. The RED circle represents the position of Jamie Pye ZL2NN in Picture 1 of ZLW Remembered. The arrow is the direction he is looking
Back to top

ZLW External Transmitter Hall 1960

ZLW Transmitter building 1960
Picture 18: Transmitter Building 1960. About twice the size of the current building and the building of 1912. Separate standby generator shed
Back to top

ZLW External Transmitter Hall 2006

ZLW Transmitter building 2006
Picture 19: Picture of transmitter building taken in 2006
Back to top

ZLW Transmitter building 2006
Picture 20: Transmitter building has been reduced by about half the size from that of the 1960s. Standby generator shed has gone. Front door is now in South facing wall as it was in the 1960s. The cell phone equipment building is in the 1960s entrance way and parking area
Back to top