The infamous TCA R5223 Military Communications Receiver

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Web pages with information on this receiver:
Ray Robinsons excellent web site
Ralph Klimeks site entitled "The poor mans' Larkspur"

I was an apprentice at Philips and worked on these when they were being made in 1965. Telecommunications Australia was a subsidiary of Philips Hendon works in the Suburb of Hendon South Australia. As I have been collecting BoatAnchor radios for many years I jumped at the chance to acquire one from a fellow who was selling all sorts of odd items, most not radio related. I could not try it out so I took a chance and paid A$100.00 for it.

When I got it home I removed the twenty four screws that held the radio inside its robust sealed cast aluminium case and was greeted with a strong smell of burnt transformer. I put it away in the junk shed but passed the message round people with a similar affliction to mine that I was looking for a transformer. Luckily the fellow who runs the Signals Collection at the National Military Vehicle Museum in South Australia had several remains and was willing to let me take what I needed out of one of the carcasses.

Signals Collection
National Military Vehicle Museum
The address of the museum is: 10 Sturton Rd, Edinburgh SA 5111. They need your help! The museum urgently needs to raise funds in order to purchase the museum property, otherwise they may be forced to close or sell off part of the collection.

I also found what I was sure was another transformer at a buy and sell. Now I had a transformer and a radio that would show me how to get it back together. Just as well because when I took the burnt transformer out of my radio I drew good clear diagrams of where each wire went and then when I wanted to put a transformer into my radio many years later the diagram had vanished. I had written it on a sheet of metal and I suspect I forgot what it was and recycled the metal for another project.

My first R5223 sat in the junk shed until May 2016 when I was given another one by Rod, a fellow member of the North East Radio Club. Rod was having a clean up in his shack trying to make room for new projects. When he learnt I had worked on building them he decided I would give it a good home. I found a shelf to accommodate it in the shack, plugged it into the power and turned it on. So far so good, it worked but was very noisy, lacked sensitivity and calibration was way out. This meant I had twelve BoatAnchor receivers to connect an antenna to and my receive only antenna switch only has eleven positions! I could not decide which receiver to disconnect so I looked around for an alternative. Time to add another receive only antenna.

It was then that I remembered had an ideal candidate, Des also a fellow member of NERC, had found an interesting item at a country weekend market, an Aegis All-Wave Noise Reducing Aerial System Type AF-1 See the photos of the lid of the box it came in below. My TEV4 multi band vertical is mounted on top of a three metre pole attached to a verandah post and so I lowered that pole and attached one end of this antenna just below the TEV4. The length of copper wire for the actual antenna is forty feet long and it fitted across my block on an angle to an aluminium post cable tied to a fence post near the bottom of the yard. This post was made from tubes salvaged from a destroyed HF beam by joining two sections .

The antenna has two matching transformers, one at the end of the long wire and another connected to it via a balanced line made from twin flex. I mounted the second transformer inside the verandah, fitted a BNC connector in place of the green and yellow wires and run about eight metres of second hand 75 Ohm coax into the shack. I could now hear some friends chatting on 40 Metre and could resolve their SSB signals eventually when I mastered how to drive the BFO and tuning.

Spurred on by this triumph I rescued the other R5223 from the junk shed and moved it into my radio workshop along with bags of parts and removed metal work. Not wishing to take the transformer out of the parts radio I fitted the second transformer using that radio as a guide to where all the wires went. I also made another lot of notes and diagrams. When I fitted a mains fuse and turned on the "smelly" old box of bits on and was disappointed to hear the fuse "pop" and then the lights went out in the workshop. The radio had triggered the safety switch.

Time to run an insulation tester over the mains power wiring and to my horror that read almost zero ohms. Was the second transformer faulty, should I have tested it before I installed it ? I then removed the transformer from the parts radio and installed that only to be greeted by the same problem. I had run the "Megger" over both transformers by now and neither was faulty. To cut a long story short after much disconnecting wires from the transformer I eventually found there was a short circuit on one of the wires between the voltage selector and one of the taps on the transformer. As it was for the 200 Volt tap I disconnected it and insulated it out of the way with heat shrink.

I fitted another half Amp fuse and that popped instantly. Was I about to find out what cooked the original transformer? Again to cut another long story short, after much removing wires from the transformer and disconnecting the heater wires from each module I fitted a two Amp fuse and was greeted with fire works inside the 6X4 rectifier tube, it was flashing over between the two anodes. Now I can see what happened to this radio, when it is sealed away in its water tight box you would not see the fire works or the smoke and my guess is someone had replaced the mains fuse with a much higher current rating fuse.

After putting all the wires I had removed back and fitting a good 6X4 rectifier I was pleased to hear noise from the speaker and I was able to tune to a station at the top of the broadcast band. There are still some issues, the worst one being fire works inside the panel meter every now and then.

When we were building these radios in the 1960's we had to use Australian made carbon resistors as there would have been a hefty tariff on imported components. I remember the resistors were packed in bags and the story behind this was they had been tested and certified to be within 5% tolerance by workers somewhere in the Army stores. There was also a story that this was done about ten years before we started to assemble the radios as the project took a long time to get started. I can remember running an ohm meter over some of the resistors and finding they were already up to 20% high in value even before they had been put into the circuit. When I brought this up with the boss I was told it would be too difficult to do any thing about the problem, just put them in and say nothing.

The photos below are of the second R5223 I have, SN 094 on the front and SN 77 on the inside. Both of my radios are missing the simple Brake mechanism so if you have one you can make a drawing of then that would be good. Email me a JPG or PDF file with a few dimentions written on it.

To be continued when I get more enthusiasm to work on this project again. In the mean time I am reading and making copies of the material on two web sites that tell of the trials and tribulations of keeping an R5223 working. Resistors that go high or open circuit, ceramic and mica capacitors that go leaky or change value in "leaps and bounds" and IF coils/transformers that are very fragile. One fellow has a good solution for IF coils that are beyond repair, use two little transistor radio cans back to back. This was a solution used by Silicon Chip in a valve radio project a few years ago. I am going to make small circuit boards to replace the bakelite boards in the modules and will use the "can sets" from Jaycar or Altronics.

The first three images above are the insides of the radio with several modules removed, and the next two show how the dial chords are strung. The wire is tracer wire from a fishing tackle shop and you will need to use a small eyelet or thin brass tube for the ends.

The first of these photos show the compartment under the power transformer, the next two are of the RF stages, then there is one side of the calibrator module, the IF modules and and then the VIF and the other side of the calibrator module.

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Written by and Copyright, Phil. Storr © Last updated 24th May 2016