AWA BTM-2M AM Transmitter Rescue
This is the Story of the Recovery of the AWA BTM-2M AM Broadcast Transmitter from the 4CC transmitter site in Biloela.
Thanks to the efforts of Keith Evans and Brandon Gordon VK4VIP for allowing us to save the transmitter and arranging a time for collection.
Also thanks to Ray Robinson for keeping me awake on the trip up and assisting with the heavy lifting.
This Transmitter was installed into 4GY originally as a brand new transmitter in late 60's and it was set to 1350 KHz at the old transmitter site at Monkland Queensland, it was then moved to Wolvi, Queensland in 1975 as TX No-2 with a new main TX being a RCA 5 kW Ampliphase.
It was set to a new frequency of 560 KHz and to 558 KHz in 1978.
It was de-commissioned in 1986 when a new MW10B went into the site as the new main transmitter for AM Stereo and the RCA TX became TX- No 2 as a Backup TX.
GY was owned by Wesgo at this point as was 4CC, so the AWA transmitter was moved to Biloela in the late 80's and upgraded in the early 2000’s.
The AWA transmitter was operated as the Backup until parts became an issue whereby it was decommissioned until its removal by the Tube Radio Australia Team, Ray Poularas and Ray Robinson.
Model: AWA BTM-2M
Serial Number: 43
Power: 2.5kw (2500w)
Power Requirement: 3 Phase 415v & Single Phase 240v
Filament Hours: 0648564 (taken by front metre)
Dimensions: Height- 2.23m, Width- 0.98m, Depth- 0.93m
Weight: 1750 pounds (as per the manual) 800+ Killos
This is a piece of History for 4CC Biloela and as of the 18-04-2016 has gone to a new home in Sydney.
The old original AWA Tube AM transmitter that provided listeners with music and programs on 666 kHz from Biloela for many years in the 80s, 90s, and has now finally been removed, after it was replaced with a new state of the art, fully Solid State AM Transmitter.
The AWA BTM-2M transmitter built 1966, It ran on 3 phase 415 V power and drew 20 Amps per phase at full output and 100% modulation.
The control circuit, minor HT, air blower and filaments operate on single phase.
The 5,500 V a.c. three phase transformer cannot operate on single phase. It can be run again as before but only when the 3 phase contactor for the High Tension closes onto the 3 phase power.
It’s now gone to Sydney to be placed in a museum and will be converted to the 160 metre amateur radio band on approx. 1843kHz AM. And run at legal limits for Amateur operations.
The Transmitter in its original position…
The new transmitter solid state, only two racks of kit
The Two Modulator tubes and the RF PA. Driver section for the Modulator and crystals
Rear View with the Power Transformers remove.
Dissconnecting the 240v and 415v mains, note check three times and then ground test everything before unscrewing the terminals…!
The Modulator sockets
PA tube and Blower output
The 4cx 1000’s
The blower unit
Bottom ot the TX……
The three phase transformer …. Very Heavy.
The LV Power Choke with two smaller transformers and the Capacitors
Sliding out the three phase transformer..
The rear of the TX…
Close up of the three phase transformer.
Low Voltage side of the main transformer.
Oil Filled Capacitor No 1 the Big one….
HV Choke transformer 5000V
Choke HV 5000V
Blower Unit for the output tube, to prevent the tiube from overheating with continuos use
Low Voltage transformer 350v and 250v
Disconnecting the RF cable, the transmitter that was running next to this transmitter had to have the power reduced so that the risk of cross RF was reduced. Even without a direct connection the RF can be induced into the Tank coils from the active transmitter and give you a nasty RF burn or worse.
LV choke Transformer Note the Ceramic terminals. This needs to conduct massive current so its Heavy.
Disconnecting the Earths
Nice shot looking down the front panel, note the two 6146 driver tubes for the 4CX100 Modulator tubes and the test meter built into the cabinet. Ray Robinson working on the front door hinge. Notice the Test meter, according to the diagram it has RF and 5000V across it, so its mounted inside the cabinet.
Small Cap is Out
Driver Tank to the PA output tube….
Glass covers on the Modulator tubes Very Dusty and Dirty inside
Modulator Deck shots
I know that door will come off, its just rusted on
The door is finaly off….
Making the first Cut on the Mains after isolation of the TX..
Dissconnection of the three phase transformer
Three Phase connections
Blower unit needs attention
Nice shot of the Antenna inputs from both Masts into the switching and loading coils, with Ray holding the removed output cable.. No RF burns and its all safe.
Special safety boots and standing on the RF insulating stand….!
Making the RF antenna Cut….
LV transformer connections
HV three phase connections
Closeup of the 425v and 240v connections
The transformers are out
Getting it out the door from the transmitter shed, Note the transmitter was too big to come out standing up, which leads me to believe the shed was build around it….
Yep now how to get this 350KG transmitter case onto the trailer??
The look of contemplation, how are we going to lift this?
Hmmm…. It’s very heavy…!
Yep too heavy to move into the trailer by hand..
Special tools needed a Hand winch
Strapping it up
Timber skids reminiscent of building the Pyramids
Ready to go….!
Pull it up….!
On its way up the ramp
Last lift and its in the trailer….
What do you know it Fits….!
Strapped in for the trip
On the road
Spare RF cable
Mains isolated and insulated