VK5TM


News, Updates and Other Minutiae

I have, for quite a while, provided modified versions of the code for my projects free of charge. However, the cost of webhosting for this site has tripled in the last couple of years and the little I make out of the pcbs I sell goes nowhere near covering this cost.

As of October 2017, I will be asking for a donation in exchange for providing custom modified code for my projects to help keep this site available.

November 2017

A modification plus software to allow the Simple DDS VFO to be re-calibrated as often as you want without having to re-program the PIC has been added to the Simple DDS VFO page. Simple DDS VFO bug problem fixed. Code uploaded to webpage as version 'c'.

October 2017

There is a bug in the Simple DDS VFO code. See Simple DDS VFO page for the problem and updated code. Included an add-on for the Simple VFO project to indicate which step size has been selected. Simple DDS VFO project updated and software file uploaded. The pushbutton on the encoder is used to change step size (step sizes 10Hz, 1kHz and 10kHz).

September 2017

Noise Canceller kits now available.

July 2017

Updated both the DDS Xtal Substitute and DDS Xtal Substitute Mark 2 projects into one project. The original webpages are available to download as PDF's.

May 2017

New project added - my version of the X-Phase noise canceller. PCB available and a kit of parts to follow soon

Old Valve (Tube) Radios

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. Top view of old Precedent radio chassis Bottom view of old Precedent radio chassis 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. Front view of unknown chassis Back view of unknown chassis Variable inductance tuning unit 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.