Category Archives: HF

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.

Amateur Radio Transponders on Planned Chinese Satellites to Include HF

From: The ARRL Letter” 24 May 2018

China’s Amateur Radio Satellite organization, CAMSAT, has released some details of three new Amateur Radio satellites that could be launched as early as September. Two of the satellites, CAS-5A and CAS-6, will carry transponders; one will have HF capability.

CAS-5A, a 6U CubeSat, will have an HF/HF (21/29 MHz) mode linear transponder; an HF/UHF (21/435 MHz) mode linear transponder; an HF CW telemetry beacon; VHF/UHF mode linear transponder; a VHF/UHF mode FM transponder; a UHF CW telemetry beacon, and UHF AX.25 4,800/9,600-baud GMSK Telemetry. Transponders will have 30 kHz passbands, except for the H/U unit, which will be 15 kHz.

The tiny CAS-5B, weighing 1/2 kilogram, will be deployed from CAS-5A in orbit. It will carry a UHF CW beacon on an Amateur Radio frequency. It will be placed into a 539 × 533 kilometer, 97.5° orbit.

CAS-6, a 50-kilogram microsat, will include a VHF CW telemetry beacon; a U/V mode 20 kHz linear transponder, and AX.25 4,800-baud GMSK telemetry downlink. It will also carry an atmospheric wind detector and other systems that will operate on non-amateur frequencies.

A launch at sea is planned for CAS-6, which will be placed into a 579 × 579 kilometer, 45° orbit.

CAMSAT has applied to the IARU to coordinate frequencies for all three spacecraft. — Thanks to AMSAT News Service via AMSAT-UK

To talk or not to talk?

After being away from the hobby for around 5 years I am surprised by the uptake of digital modes. I wonder what this means and where it is going.

It is not that I have not used them in the past, in the early 1970s I had a Creed 7B teleprinter connected to a home brew terminal unit taking audio from a modified Pye base station on 2m. It was part of a local net and was left on standby a lot of the time. I would come home from work and find a few feet of paper on the floor. RTTY using the computer is not the same. No smell of 3in1 oil or the noise of the motors and clatter of the mechanics.

Video of a Creed 7B

 

I also found WSPR to be useful to test antennas and tried a few other data modes but frankly I found them to be boring. Yes, they can establish a 2 way connection where other modes cannot but so what? It is machines talking to machines. There is no experience of making contact with a human being, no suppleties of voice or ‘fist’ in CW. Nothing to personalise the contact and gain some idea of who you are connected to.

For me radio is about connecting, communicating with another person using voice or Morse. It is about recognising that there is a human being operating the equipment, making the connection, the contact. And I mean ‘contact’ in both the human communication sense as well as the technical sense.

I fear that digital modes are being pushed hard as a way of interesting younger people in the hobby. I must ask why? Why do something in a more expensive and complicated way that can be and is done by Snapchat, Facebook, Instagram etc?

A few years back when Internet linked repeaters started I remember having a conversation with a newcomer who was excited about ‘working’ a VK via the local repeater. In fact, he worked the repeater a couple from miles from his house but was under the impression he could get DXCC and other awards easily. That is the problem, the quick and easy fix appealed but took him nowhere.

I still believe that if you show a real contact on a radio with someone in a far-off place it will be more exciting and more attractive than dangling the instant hook of digital communication. Kids do that on their phones every day, why would they bother doing it via radio?