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.

As a lot of people have pics of things unrelated to ham radio on their websites, I thought I would add a couple of my own (Scroll down for site updates). Banjo, our Red Heeler/Koolie cross at 4 months old. Banjo at 4 months And at 12 months old (Feb 2016) enjoying his birthday breakfast treat of banana on toast. Banjo at 4 months A new addition to the family, an 11 week old kitten (end July 2017), rescued by Banjo after being trapped between a water tank and fence. Her name is Storm after her colouring and it's eating a bit of toast and jam (yes, our animals do eat strange things, including lemon meringue pie). They are now the best of friends. Storm at 10 weeks

October 2017

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

27 December 2016

Another addition to the Gallery section. This time, fitting a DDS module to a Philips PM5326 RF Generator to cure a bad drift problem.

DX160 Mods

Mods I have made to my DX160

While waiting for some parts to arrive to continue on with the DDS signal generator, I thought I might as well do some mods to my DX160 receiver. While the DX160 has a nice dial with smooth operation, it is not easy to determine exactly what frequency you are on. It also does not have an audio out socket to enable recording of anything received. The first mod was to provide an output to drive a frequency meter. On the 'net, there are several sources of information for fitting a frequency meter. Most revolve around either tapping off from the local oscillator output or at the mixer with a 68pf cap. I tried this, but connecting or disconnecting the frequency meter would shift the local oscillator frequency somewhat. Not really the most ideal situation. My solution was to fit a FET buffer stage. The local oscillator frequency, now, does not change at all when connecting or disconeccting the frequency meter. This is the circuit I used, nice and simple. FET Buffer schematic This was connected to the top of R12, which is the mixer point in the DX160, as shown by the red arrow in the schematic fragment below. Power for the FET buffer was taken from the local oscillator's stabilised 7v supply (next schematic fragment below). DX160 schematic fragment, mixer DX160 schematic fragment, power Here are some pics of the mods, first, FET buffer (built dead bug style), second, mixer tap off point and last, an overall shot of the area showing the buffer power tap off point. Dead bug style FET buffer Mixer tap point Power tap point Next mod is a simple audio tap off. All it is is a 0.1uF cap connected to the top of the volume control and a piece of coax to a socket on the back panel. The cap in the picture is an 'X2' rated cap, used not for it's ratings, but because that was the closest at hand at the time. Audio tap off point To accomodate easy connection and disconnection of the frequency meter and to connect an audio recorder, a BNC socket and 1/8th inch mono jack socket were installed on the back panel. New rear connectors The 'purists' will go 'but you're destroying the resale value doing that'. Guess what? I don't care. The DX160 is not a collectable, they are reasonably plentiful and can be bought for $50 on average (2012). Besides, I intend to keep it until I fall off my perch anyway, so that will be someone elses problem. Having got the easy connections via the rear panel, I didn't really want to have a seperate power supply for the frequency meter. So, mod number three. There is a three pin sockect on the back to enable the DX160 to be powered from 12V. The pins are in a 'Y' arrangement, with the one at the tail of the 'Y' being ground or negative. At the top of the 'Y', both pins were connected together to form the positive connection, so I seperated them and connected a wire from one of the pins to a point after the main regulator. If you go back three pictures, you will see the orange wire I installed. NOTE: do not connect or disconnect anything to this with the DX160 turned on. I've already blown one fuse doing that. The lights will stay on, but nothing else works. Modified rear power connector The orange/black twisted pair are power out (approx 9V) and the red/black twisted pair without a connector on is 12V power in (diode protected for reverse polarity). I haven't done any measurements, but I doubt this power out connection will support a frequency meter with a backlight. Extra modifications to the power supply of the DX160 would be required for that. Finally, here is a shot of a frequency meter connected and working. This one is a design of IK3OIL (search the net by his callsign for info). I have to find a box to fit it into, but it works marvellously. Frequency meter connected and working I have made a download available of the service manual. Please note that there are two versions out there on the 'net. One for the early version of the DX160 (like mine) and another for the later version. The main difference between the two is in the audio stage.

Downloads (Right click and 'Save as..' or what ever is required by your browser)
DX160 Service Manual