Hardly bedtime reading, but valuable resourses none the less. Even if i have to sit at my desk to read the damned things. 🙂
So a few weeks back I got making this nice looking lab power supply, but other than running my bench LED lights, its not been used. And thus begins my world of hurt, because the other day I had a project that needed some power and after connecting it up, things just were not doing what you would expect them to do.
A circuit that should give a nice sine wave looked a mess on the scope, a receiver I powered up had this god awful switch mode racket on just about everything. So get get the pixie wrangling gear out to take a look at what was going on and it was nice a pretty picture.
As you can see from the scope output, the 12v DC was not pretty and it was making my projects not happy. So i figure, It needs a filter and I do 30 seconds of math and figure 10 to 100uh of inductance with 100uf of capacitance should be close to enough to the business.
So I make a nice looking filter and connect it up to the power and yes it attenuated the noise and ripple but it really did nothing else, all the problems were still there.
When you know you are chasing your own tail, start talking to the smart people. In my case this is Brenton, and we got talking about all aspects of the design, what modules I used what SMPS i used and a bunch of other specifics.
Well it turns out, had a fundamental flaw in my PSU design, I had left the 0v DC floating and this is a trap for young players. Because in the words of someone smarter than me “Without that connection the output is magnetically isolated and noise leaks out via capacitive coupling in the output transformer.” So after checking that 0v DC was not tied to Mains Earth, they were quickly coupled together and all my problems went away.
And as you can see from the first scope output above, the power is now rather clean, and in the 2nd scope output, is the DC after my new filter. The filter will be installed permanently in the next few days and will remain a permanent part of my lab power supply. And with that fixed, we can get onto building a receiver now for the 10w CW transmitter.
I am not much of a straight key user, but I am building one anyway to be a park of my novice station. The hinge is brass, the arm brass, the knob is a a button i found in the wifes sewing collection and the spring is one i picked up from the hardware store and the base is red gum.
A little progress, using the cnc, routed down the board, retaining a plinth at the rear to mount the arm to. Need to drill out a recess to house the spring, and also another for the contacts at the front. I have some Copper rivets on the way to use as the contacts and some longer brass bolts for other side of the contact, with tapping the bar and a lock nut, the contact gap will be adjustable.
So I was doing some log maintenance and uploading logs to all the essential services, LOTW, EQSL, Club Log and while i was looking at club log, I noticed that as far as the DX i work goes, it is predominately using CW. I figure that due to the inherent efficiency of the mode, those of us with low power stations and less than ideal antenna situations, have a better chance of working DX than if we are using Phone only.
And when i look over some of those Pacific Island DXpeditions that have taken place over the last month or so, I have not heard them on Phone and they have been weakish even on CW, but I have still managed to get in the log even when they have had substantial pileups going, just by listening and working out where the operators are listening to the pileup. In this instance, with CW skill over brute force wins every time. And in a phone pileup I get swamped, but in a CW pileup, i can spend 20 mins finding just the right frequency to call on and be heard over the bigger stations calling either side of it.
So the final installment of all this activation activity was The Great Sandy. We were camped on Lake Cootharabra and I used this as my base camp for the activation’s of Tuchekoi, Tewantin and Woondum. I did not put a full activation of this park on as I have done it a number of times already. But rather just chased the other activators for park to park contacts.
We had this pair of ducks decide that our campsite was going to be their campsite for the whole weekend. They slept under the table, chased away any other birds and pretty much took ownership of everything. Pretty funny.
Woondum is also another new park. It is also a SOTA peak and i did a dual activation for both programs. I am not much of a SOTA person, this was my first SOTA activation ever. SOTA in vk4 is a lot of work for little reward, most peaks are low value, this one was 1 point, and most require a lot of effort to climb to the summit.
Anyway, this summit was also a drive up and a short walk. I made 56 contacts from VK1,2,3,4,5,7,8 and ZL. As well as park to park contacts with VK4AAC and VK3ANL. It was also nice to have Sid and Adelle ZS5AYC and ZS5APT call in, who are both back in VK4 again visiting with family. Both are very keen on SOTA and will be out and about doing activation in the not to distant future.
Activating Position APPROX -26.262834, 152.813716 using google maps, need to use SOTAMAPS to get the exact summit co-ords.
Sometimes when laying out a board you have to create your own footprints. Out comes the digital calipers and you start making measurements, but, what if you make a mistake, the board becomes a waste of time. So, i like to print out the board layout at 1:1 resolution and then overlay my parts and where possible push the pins through the page to check everything lines up right. Saves in the long run 🙂