Category Archives: Radio

Pure 160m

I could not resist this! A RAT5 160m AM receiver in a Pure Evoke DAB radio case. It came into a repair cafe where I volunteer. It had been well and truly zapped when the PSU went faulty. I asked if I could have it for the bits. The case is a bit battered, but I am sure it will be fine.

The RX is built and working and there is lots of room for the TX, the FAT 5. Both come from
www.shortwaveradio.co.uk/projects.htm I have no connection other than buying the kits.

More to come.

Life is too short….

Last week I heard a QSO on 80M SSB where each op was using 400W and each gave the other 5-9+20db One op said ” I always use QRO, life is too short for QRP”. Reducing their power to ~6w would have resulted in report of 5-9+2db. Why waste so much power?

Interestingly I found this today on the North American QRP CW club web site; “According to Rich Arland, K7YHA (now K7SZ), in World Radio magazine (Feb. 1990, year 19, issue 89, pp. 46-47) the long-distance low power record is held by KL7YU and W7BVV using one micro-watt over a distance of 1,650 mile 10-meter path between Alaska and Oregon in 1970. This is the equivalent of 1.6 billion miles per watt.”

That is why I use CW with a 5W power output limit and often use much less. It takes more effort to work some stations and more skill and patience but the rewards are well worth it especially when using homebrew gear.

SW20

160m – Topband – best for solar mimimum

I was digging around on the net today looking for simple deigns for Topband,  160M gear.  I found this article saying that it was best for solar minimum:  “The 160-Meter Band: An Enigma Shrouded in Mystery” which first published in CQ magazine in 1998. Here is some of what it says:

“Topband is one of the last frontiers for radio propagation enthusiasts.”

“The correlation between sunspot numbers and signal strength is only about 5% as strong as the correlation on higher frequencies.

”There are several important components that can improve your chances of successfully working DX on Topband. […] The trick here is to wait for sustained intervals of quiet conditions over the high latitude regions.”

It used to be the band for local rag chewing and I get the feeling it is either classed as just that or seen as the preserve of DX chasers with huge antennas farms. It can be both, but we can all have fun on Topband over the coming years without the constant depression of low or non-existent sunspots. I have a 38m long inverted L and had reasonable results on 160M a few years back so please do not dismiss the band without giving it a try.

It also appeals to me because it was my first intro to amateur radio. I used to look out of my bedroom window across the road to an aerial pole in the back garden of the next street. It belonged to G3LIO, Jim Gibbs. He was the first licensed amateur that I knew, and he and his father were very generous in helping me to start short wave listening back in the mid-1960s.

I have a few projects to complete to get back on the air but over the coming months I will make some Topband gear and give it a try. It will be low(ish) power AM to begin with. I also like the idea of working /P with long wire antennas supported by tall trees. It is time to modify the catapult launcher!

Can we talk?

After 6 years away from the radio what is different? Everything and nothing. Still the same camaraderie and immense kindness in the hobby. That has not changed. The difference is there seems to be a growing reluctance to actually talk to each other on the air.

What has become apparent is the reliance of the internet. I saw a message on the net recently from a VHF op who said he had spent a long time calling CQ with no response. The reply was that he needed a ‘spot’ on the ON4KST site and then people would know he was there. I assume from that nobody turns on the radio and tunes around anymore.

Then there is ‘the HF bands are dead’ mantra usually followed by it’s not worth turning on the radio as there is nothing much on the DX cluster. Again, it looks as if ops are sitting in front of their computers waiting for to see something happen instead of using their radios.

And the automated digital QSOs, jt8? And digital propagation checking where you don’t even need to contact another human being to know how far you signal has travelled.

Is that what it is all about now? Only operate when there is DX around? Never call CQ because nobody is listening?  But what gets me most is never ‘talk’ (voice or CW) to another human being? Have radio amateurs lost the ability/desire to speak to each other?

Don’t get me wrong, I am all for using the latest technology and moving with the times but if we insist on removing the human element or reducing it to the shortest possible exchange for the points or to bag another country then we lose the very basis of the hobby. There must still be a place to rag chew on 160m or 80m or 2m, I want to talk to another human being and not a computer.

What is a redpitaya?

Doing a lot of home construction is helped by having a heap of test equipment. There are several ways of getting that; take a risk on eBay and buy old stuff, build your own or get a redpitaya.

It claims to be able to work as an oscilloscope, signal generator, spectrum analyser, Bode analyser, logic analyser basic, LCR meter and vector network analyser.

If it can do all then it is truly revolutionary, and I want one! It is not cheap but if you add up the costs of the single instruments it replaces then it is definitely NOT expensive.

Using SMD – part 1

Why do I like using SMD? Let me explain, I began making radios using valves, it was all there was at the time. When I started work in the industry the first training courses were on valves and how they worked. Then the transistor came, then integrated circuits followed by surface mount devices, SMD. I guess I have followed the technology.

It is easy to be overwhelmed by progress and stick with what you know but there are many advantages to using SMD:

  • individual components, resistors and capacitors, are very cheap
  • many older devices are no longer available as wire ended e.g. the SA612
  • PCBs are smaller due to high packing density
  • high frequency boards are easier and cheaper
SI5351 board

An SMD VFO module

Above is an SI5351 board (ready made apart from soldering the SMA connectors) it is just 30mm wide and can used with an Arduino to make VFO with 3 programmable sine wave outputs. Current cost is less than £5 on ebay plus the Arduino.

You might need some new tools like a magnifier, fine tipped soldering iron and good quality tweezers. There are more including heated tweezers and a hot air gun for component removal but they can wait for a while.

So, my advice is do not be put off and have a go. Find a simple kit to practice with and then progress to more complex circuits. It helps if you know something about how SMD components are sized. Srat with the larger sizes and work down.

1206 and 0805 are popular SMD sizes

This is another good one to print out.

Over the coming month I will add to this series of posts and share some of the projects I am working on which include: a remote tuner, vector network analyser (VNA), wide range VFO/signal generator, a switched attenuator.

The antenna

The antenna is back up after 6 years! Nothing fancy just an inverted L at about 11m (~35ft) and around 38M (125ft) long. Still need to put in a counterpoise in the lawn but the ground is rock hard after weeks of drought, so it will have to wait.

Also need a remote tuner and plan on making one based on an Arduino.
https://hamprojects.wordpress.com/2016/12/31/hf-automatic-tuner/

I have a nice waterproof box that housed a commercial tuner to house it and will probably make it solar powered to avoid have to DC up the coax. Hope to get the coax in this week, it is something like a 40M run of RG-213. So, work to do before winter!

A scratch build Wilderness radio SW-20

This is an amazing build of a favourite of mine, the Wilderness radio SW-20. It shows just how neat and effective ‘ugly’ construction can be. In my opinion it is far from ugly!

I would love another but they are no longer available. Maybe this is what I should do over the winter – build one!

It is interesting that he started with the case and cut the copper clad board to size. It seems like a very ordered way of working.

A Scratch-Build of N6KR and Wilderness Radio’s SST for 20M

I had one of these radios a few years back and made many contacts on it. I did some mods but cannot remember what the function of the extra knob on the left side.

QRP does work!

Time and time again I see the trite remark that life is too short for QRP. Well, QROers you can do amazing things with very small amounts of power! Oleg Borodin, RX3G and Leonid Bovin, R1LB have completed a QSO on 14.060 over a distance of 970kms with each using 80mw. Congratulations to you both for keeping real amateur radio alive.

Life is too short NOT to try QRP!