AmateurRadio.com

Hi all,

The Lydford from Walford

I am in the process of updating radiokitguide.com.  If you can think of any new kit sources that I haven’t covered yet, please leave a comment here.  I am looking for RECEIVER, TRANSMITTER, and TRANSCEIVER  kits.  I will cover accessories at a later date.  If you know of a spectacular source of accessory kits though, send it along anyway.  I am adding a couple of new sources, and making changes to YouKits, Small Wonder Labs (goodbye), TenTec, and several others.  Thanks in advance for your help!

Conditions seem to have been pretty good on 10m over the last day or two. Yesterday, as I was driving back from the convention the band was buzzing! I concentrated on 29MHz AM and was interested to hear N4ZED coming in from Georgia. I called but although Ken could hear a G there he wasn’t able to pull me out. Hardly surprising given my low power. I was surprised he heard anything at all,

This evening AM was quiet as I was heading home, but the SSB portion was lively. I managed a quick fire contact with K8CW which I was happy with, running 10W or so to the whip.

This is really something. Now I can hear actually John N8ZYA my fellow blogger. I am always looking out for well-known hams out there. John is one of them, so far I was not successful. Thanks to NG9D for sharing this video.

10 meter was very good yesterday. I heard Greenland, which I do not hear every day. The JT65A portion of the band was very crowded. Instead of the PSK31 portion. A new trend?

With JT65A I worked TA2EM on 10m which was wide open. With CW I worked: K9LJN, A45XR and VE3EN.

Whilst leaning out of the car window and manually turning my decorators pole (complete with 70cms antenna) and waiting for a break in a UKAC (VHF Contest) QSO I thought that there must be a better way of doing this.

The antenna weights way less that 1Kg and the decorators pole has a perfect coarse thread to it so it shouldn’t be too hard to make up a simple attachment with a stepper motor on it, driven of course by the mighty Arduino and its motor shield

Although I’ve not put one of these together and its a bit of a pipe dream whilst work keeps sending me all over the place I’ve seen more that my fair share of articles that use the motor shield to drive stepper motors (guessing its some kind of H bridge / relay arrangement). So I’m guessing (again) that the bare bones of the system could be pulled together over winter. ready in time for next years UKAC series.

I enjoy the UKAC series but running /P has its unique problems up here in West Cumbria. As I type now the winds are getting stronger and we expect the gale force variety over the weekend. Even when we’re not being blasted with salty Irish Sea venturing out /P means that having a car window open in the winter on the top of a hill is ‘challenging’.

So the challenge is on me now to come up with something now that my work project is attempting to shift from ‘Madness’ to simply ‘Frenetic’ between now and November and possibly simply ‘Stressful’ in December.

Once that’s done…hah ha…I’ll concentrate on the single boom  6m / 2m /70cms antenna I’ve been thinking about that means I don’t have to crawl around in the dark with loads of bits in the car.

Still if someone’s done it already, please put me out of my suspense.

It’s always nice to find that other people’s findings match your own. PA0RDT is famous for his design of the mini-whip, a very small but effective long- and medium wave antenna. Roelof found that the magnetic component of a radio wave could more easily go through obstacles, while the electrical component was more contained within a closed space, like a house. This means that the electrical component of noise generated by appliances in the house stays inside – mostly – while the magnetic part travels outside the walls. Thus his mini-whip design picks up the electrical component only and amplifies that. If the antenna is placed some distance from interfering obstacles it will result in a strong, but relatively noiseless signal. I build one and can say it really works.

But amplification comes at a price: IM and overload. Passive loop antennas have non of the afore mentioned problems. Since the beginning of my radio days I have always had a one metre square loop antenna for MW and LW and deep in my heart I longed for one. So I build one again, but this time bigger: 180 cm square with the corners clipped. Tuning is done remote with a BB112 varicap. The circuit was once published by the Benelux DX Club and I’ve had it for over 25 years, but never build it to this day.

Because of bad weather I could only put it up last weekend and boy, what was I disappointed. It seems it picks up all the television noise from the whole neighbourhood, with added noise from within my own house. The mini-whip is clearly better than the loop, so PA0RDT is right. But using another laptop power brick helped a bit and after firing up Argo it seemed that despite the noise the loop was still proving itself useful.

The loop tunes from 136 kHz to just above 400 kHz, which covers most of the NDB frequencies. Even though long wave beacons are on the decline there are still a lot of them. I heard some 30 new ones over the weekend, both in the daytime and at night. Argo is a great tool, sometimes beating my ears in picking up signals. Here some screen shots.

Locator “O” on 201 kHz and PQ on 202 kHz, both unidentified.

An odd one heard on 220 kHz: BRBA5. Notice that the dash in the letter “R” is longer than the other dashes. Ears won’t notice this, but with Argo you can see it.

Three beacons on the same frequency of 380 kHz: LM, OB and sandwiched in between YU from Hualien (Taiwan’s east coast).

NDBs are fun to DX, but my goal is to do some 2200m DX. Without any voltage applied to the varicap the loop is tuned to 136 kHz, which means I can leave it on all night and hope that I can detect some signals from Japanese hams, or maybe the Philippines. Unfortunately Chinese hams are not allowed to use 2200 meters and I don’t know of any Taiwanese hams operating this low. Help! I think I am becoming “low-nely.

Here’s a design for a 1 MHz amplitude modulated (AM) transmitter. I’ve been looking a while for something like this, a simple short range AM transmitter for the medium wave band, as I needed something for demonstration of my collection of old radios.

The result is the AM transmitter shown here in an Altoids tin on top of a Radionette Kurér radio. This is a portable tube radio from the 1950’s. Several hundred thousands were produced, and it was exported from Norway to 60 countries. It is still popular among collectors.

The transmitter is as simple as it gets. The heart of it is a 1 MHz crystal oscillator in a can. Its 5 Volt power is modulated via an audio transformer, one taken from the output of a transistor amplifier (primary 147 ohms – secondary 3 ohms). I drive the modulator from my cell phone into the low resistance side of the transformer and get good audio when the phone’s volume is set to maximum.

The design was inspired by one from Instructables, but mine also has a 78L05 5 Volt voltage regulator and a red LED in series with the power supply. It indicates that the battery is plugged in. In total the transmitter draws 4.4 mA at 9 Volts. The input power to the oscillator is less than 5 Volts * 4.4 mA or in the order of 20 mW. The power output is just a fraction of that. I have tested it with a 1.5 m wire hanging down behind the built-in frame antenna in the back of the radio with good results.

This is really just a modulated marker transmitter as I have briefly described on this blog before, and the square wave will have harmonics of 1 MHz over the entire short wave band. Some of these frequencies may propagate really well, so if used with a longer antenna, it should really have an output low pass filter to prevent that.

I’m not totally happy with this design, despite its simplicity, though. If I could, I would rather like to transmit in the long wave band at 216 kHz. This is the old frequency of the Oslo transmitter which ceased operation in 1995. As a member of the Norwegian Radio Historical Society, I am allowed to use that frequency with a transmitter input of 0.5 W for demonstration purposes.

For other frequencies, one simple alternative is a standard canned oscillator at 1.288 MHz. I also believe some of the Silicon Labs oscillators can be used in order to get an adjustable frequency, but I haven’t tried that myself.

But until I find a suitable frequency source at 216 kHz, I’ll stay with the 1 MHz alternative at a mere 20 mW. It is in line with the best principles of KISS (keep it simple stupid) or with Occam’s principle : “It is vain to do with more what can be done with less“, i.e. the QRP philosophy.

You can never please all the people all of the time! We all know the truth of that statement. I thought the programme for this year’s RSGB convention was a particularly strong one. But talking to a friend at lunchtime, he felt it was a weak one! a couple of people mentioned the lack of any contesting content, other than the trophy presentations!

The best day for me to attend was Sunday, immediately meaning that I couldn’t see GW8JLY’s Meteor Scattter and YO4FNG’s VHF DX presentations, both of which I would have loved to have seen, but they were Saturday only.

I arrived on Sunday morning and found my way to the room where Graham G0NBD was presenting on the 472khz band. Given my experiments I was interested to hear how it was being done ‘properly’. Graham’s presentation was fascinated and I came away with a few ideas. An interesting snippet was that apparently, in addition to the IC706 working on 472khz, so does the old IC735 – up to about 25 W of output!

There were also some interesting uses for the RTLSDR dongles and making them work much lower in frequency. I need to have a look at that!

I would have loved to have had more time to hear about propagation on the band, but Graham filled 45 minutes very easily and capably.

Next I headed over to hear half of the OFCOM update, presented by Paul Jarvis and Ash Gohil. I was impressed with what I saw and felt they did a good job, with a generally good natured, but challenging audience! There were some in the audience who seemed specialised in making issues where no issues existed! However, it was an interesting session and gave a flavour for the nature of the upcoming consultation on the amateur licence review.

Far from being faceless Government officials, which one might be tempted to imagine. Paul and Ash came across well, seeming very approachable and genuinely willing to listen.

After this, I was looking forward to Pete, 2E0SQL’s ‘Another slice of Pi’ presentation. At yesterday’s presentation, Eben Upton himself, from the Raspberry Pi Foundation was in the audience. No pressure, then! but Pete said they had a great and very fruitful conversation in the bar afterwards, with Eben offering some interesting insights to forthcoming developments.

Pete’s presentation was excellent and I came away with some more things to try with my Pi – particularly with some ideas for new software to try.

I didn’t fancy the Roast Pork lunch so much, so drank coffee and chatted with friends, some not seen face to face in 10 years or so. Undercurrents of ‘politics’ are never far away and I noticed a couple of discussions going on which I was glad I didn’t need to be involved in!

After lunch it was time for the presentation which had been the trigger for me to attend the convention, ‘DXing with weak signals’ by Joe K1JT. You may remember I have referred to Joe as one of my ‘Ham Radio Heroes’. I really wanted to hear him speak and if possible to meet him and have the chance to say ‘thank you’.

Joe was an excellent and engaging speaker. Although I know his software pretty well, there were some very interesting points discussed and things I learned.

I was particularly enthused about the idea of getting on 144MHz EME. Joe talked about having worked over 800 stations with his station which uses a pair of 10el X-Y yagis. This was inspiring!

It was interesting to get a sense of how the various JT modes stack up with SSB, CW and so on – just how weak can a signal be to get some intelligence out of it.

I would have quite happily listened to Joe for hours, but sadly the talk was soon over, but it was a privilege to hear him speak.

A really enjoyable and inspiring day out!