VK5TM

I started in electronics, way back in the dark ages in the UK, at a very young age and I can blame it all on my grandfather. While staying with my grandparents on holidays and various other times, they used to religiously listen to a radio series called the "Archers". To keep me quiet during the broadcast, they would put me in the cupboard under the stairs (no, it wasn't punishment or abuse), where there was this wonderous world of strange bits and pieces I could play with. This was back in the Fifties (1950's, that is) and I quickly found out these were old radio bits and pieces. Anyway, moving on a bit, I was given one of those Philips kits that made up various electronic gizmo's. From there, I joined a ham radio club and built my first transmitter, a valve (tube to those in the US) 2m AM rig at age 13. (You can hear the outcry now if you let a person of such young age play with all those nasty, dangerous high voltages these days. The nanny brigade have a lot to answer for). Which brings us to the present. For a bit of nostalgia, I thought I might like to build another copy of that old 2m rig. But where to get those harder to find parts without spending a small fortune? As luck would have it, a flyer appeared in our mailbox, advertising a clearance sale and in among the items were - old valve radio's. To cut it short, I ended up with 8 valve radio chassis, all complete, for the princely sum of $6 and I suspect all but two are in working order. Here are some pic's of a couple, to give an idea of what condition they were in. These first two pic's are from a Precedent 5 valve radio/gramophone chassis. The Precedent was the inexpensive brand of the day, with things like the IF cans being pop rivetted around the coils. Also, notice, in the first pic, the two outside pulleys that the dial cord runs over, they are made of wood. An idea for that next project perhaps? In the second pic, the circular plate that came from where the mains transformer is mounted was used to mount the tuning coils. Despite this, whoever built this particular one took great care in wiring it. Look at how straight the bare wire is and with precise bends. The overall wiring and assembly is very neat.

These next three pic's are from a chassis, brand unknown, that shows the best use of chassis space. In the first two pic's, both sides of the chassis have been used to mount valves and components. While the third pic shows the variable inductance tuning unit, rather than a varaible cap. That unit still has a nice smooth action.

The blue sticker with "ARTS & P" on it is a royalty sticker. Most radio builders in Australia of the time, formed an alliance to make use of patents and protect themselves. The Australian Radio Historical Society and many other sites can provide information, if you want to know more. These and all but one of the others have been dismantled and the parts (excluding resistors and caps) have been kept. Three of them had dial scales which are available for sale of which I will get some pic's and put here shortly sold before I could get them up here.

AWA Radiola 573 MA Repair

A few days ago (Feb 2020), a neighbour dropped in and asked if I could have a look at his old radio. Apparently it had been getting quieter and had finally stopped making any noise. It turned out to be an AWA Radiola 573 MA, which, apart from a broken knob, was in pretty good condition.

Rather than go through a boring blow by blow description of the what, why and wherefore's, it was a simple fix. The grid coupling capacitor to the output valve was near enough shorted because mice had been in there feeding on the wax (weird diets some of these mice). Below are some before and after photo's, keeping in mind this was a repair rather than a resoration, although I did take the opportunity to swap out all out of tolerance components and fit a 3 wire mains cord and fuse. Everything was done on the basis of being fully reversible if anybody in the future wants to do a full restortation on it. Even the mains cable inlet (a piece of irrigation pipe joiner) is only cable tied through an existing hole.

While doing the repair was an easy job, one annoying part was having to move back and forward to different pages in the manual to find component values and voltage readings for the schematic, so I redrew it and put all the information on the schematic (including the values of the components in later modified versions). There is a pdf version you can download below.

PDF download of schematic: 573MA Schematic.pdf