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I have been interested in the 6m (50MHz) band from the time we were originally allocated the former Band 1 TV spectrum. To start with, only a maximum of one hundred ‘A’ licence holders would be permitted to use this new allocation, but eventually the band was made available to all ‘A’ licence holders and then subsequently released to all UK Radio Amateurs in 1986.

Harold Rose G4JLH played a major part in negotiations with the Radio Regulatory Division of the Home Office (at that time the licensing authority) on behalf of the Radio Society of Great Britain (RSGB) for a small number of permits that would allow two-way operation on the 6 metre band. A group had been formed with Harold as Chairman and Harold himself recommended that they call themselves The UK Six Metre Group - UKSMG.

The first AGM was held at the 1982 VHF convention, where the temporary committee resigned to allow the formal appointment of a full committee and officers.

At the time, there were no 100W 6m rigs on the market and very few with 6m added at 10W output. I had a Yaesu 726 at the time, which was a three module rig with a choice of 70cms, 2m, 6m or 10m modules. My antenna was an old Band One TV dipole, which produced amazing results with 10W during the sporadic E season. I then modified a 10m HB9CV that I had brought back from my stint in Cape Town, and that plus a newly acquired BNOS 100W solid state amp improved my 2 way contact rate considerably.

I am listed as being the first UK station to work Czechoslovakia, Italy & Romania. I was also the first ZB2, Gibraltar station to be worked on 6m by many EU stations.

I eventually put up a five element Tonna antenna, and worked all continents on the six metre band during the solar peak of 1989/90.

50MHz is still my favourite band, even though I only have indoor antennas these days, with a short boom 3el duo 4/6m Yagi fixed ESE in the loft with various delta loops for other directions. Last year during the sporadic E season I worked 80 DXCC on five continents with JR1LZK at 9567km being my furthest contact.

 

 

Looking at the list of past recipients of the trophy, quite a few were really ‘big guns’ with special research permits to run 32db (1632W) into very large antennas. I am very proud to have been added to that list as a ‘small pistol’ operator.

 

 

In 2011 I built a short boom 5el LFA Yagi and pointed it towards the setting moon. Within minutes I heard tones from the speaker even though I was at the far end of my garden talking to my neighbour. I rushed in and there was W7GJ working EU stations via the moon, WOW. I called Lance with my 90W and he came straight back to me and we completed a 2 way EME on 6m. The path loss at 6m is 265db so that was an incredible achievement. It goes to show that regular stations can achieve extraordinary contacts with patience and attention to detail.

 

 

The 2022 Sporadic E season is about to burst into life and all the numbers are looking good as we climb Solar Cycle 25. Here is hoping the Solar Peak is a strong one and this 'little pistol' can work some more rare DX on the magic band.

 

Dick G0LFF

 

Yet more excellent project offerings from the workbench of Alex M0TOT, and this one's a cracker.

I'm very grateful to Alex for supplying me with his project documentation. If anyone else has anything to contribute in terms of self-constructed goodies, then please do get in touch.

 

Active Antenna for Rx - Top and PCB

 

Active Antenna for Rx - Top View

 

This is what Alex has to say about this really interesting active antenna:

 

"This is an unusual project; it may not be everybody’s ‘cup of tea’. Essentially it is an antenna-amplifier for receiving only, for the HF and VHF/UHF bands.

 

There is provision for connecting a telescopic whip for AM/FM, long wire, UHF and dipole. I believe the original designer, Tony Van Roon-Werten VA3AVR is now a Silent Key. The transistors can be found on the Internet.

 

I have a few spare boards, if anybody is interested in assembling this unit.

 

In order to check whether the item worked alright across the bands, I connected the Active Antenna output to my radio and attached a frequency generator to the antenna input in place of an outside aerial. Shown attached is a screen capture of the response of a 50 MHz signal on the radio. Other bands responded in a similar fashion.

 

Alex M0TOT"

 

Active Receive Antenna - 50MHz Test Signal Relayed into Radio

 

After satisfying myself with regard to the operational integrity of my new 15m monoband EFHW on the Lunchtime Net last week, I thought it time to add some complexity into the mix and see if everything continued to hold together like it generally does at my home QTH.

As you can probably see from the photograph below, having taken the A272 east to the northern boundary of Chailey Memorial Common, the dog was pretty exhausted. The good news was that the mag-mount had kept the 10m whip in place on the roof magnificently.

 

 

Once there, I dispatched the wife around the common with said dog, while I set up the radio gear. Other than the End-Fed antenna (being sensible for a moment, it's a self-constructed plywood drive-on mount with Barenco tilt-base, custom 1m alloy support pole, 10m DX Commander Classic and a home-constructed 49:1 QRO impedance transformer) I'd chucked just about everything else I could think of in the boot with which to test its capabilities.

I started with my NanoVNA to check the antenna resonance in the field as opposed to on my driveway, and surprisingly it was quite different. Sadly the radiating element was too short, but not by that much. The analyser displayed a superb-looking dip at around 21.8MHz, and with reasonable bandwidth. Click the image below to enlarge.

I'll address this length anomaly later, but I'll be cutting an element for each band, so I'll just reuse this one for 12m.

 

NanoVNA Saver

 

Next up was my LDG IT100 Autotuner connected to the trusty Icom IC-706 MKIIG. I've only rarely used this tuner, as I have my preferred MFJ-949E manual tuner back in the shack. It's a great bit of kit though, and it's going to be given a good workout this summer whilst I'm out and about. It happily tuned my End-Fed on 17m and 20m, but I left it at that for today. Too much other stuff to get through, and I just wanted to make sure it still worked and was happy on the (spare) car battery.

Last week, I invested in a Huawei Category 4 LTE USB dongle so that I can have decent internet access in the field. I don't have a mobile phone for reasons I won't bore you with, so this was the best solution for me. Having pre-configured it at home, it worked perfectly in Chailey which was surprising seeing that Chailey has only recently been connected to mains electricity and sewerage.

An old Dell laptop was pressed back into service running Windows 7 with the usual WSJT-X suite as well as some other bits and bobs. With CAT control hardware & external sound card connected, I had to do the usual dance of the Windows USB-COM fairies and then make the requisite changes in WSJT-X before letting Dimension 4 re-synchronise my clock via the 4G dongle. I was then looking at a screenful of FT8. Way more FT8 signals than I usually see on 15m, so something was working.

 

First FT8 Portable

 

A very low noise floor in the car-park helped to offset the cacophony of shoutyness from the irritating contesters on the band. A few 100W full duty cycle transmissions later and a handful of QSO's in the mental logbook (no, I don't keep a proper log either - have I no shame?) as well as an impressive number and distribution pattern of signal reports registered on PSKreporter, I moved on to my final test of the afternoon.

The Icom packed safely away, I connected and fired up my fantastic SDRPlay RSPdx SDR receiver. With SDRUno running on the laptop, the full beauty of a slice of spectrum crammed with every type of amateur transmission was displayed. I simply love this software, and chuckle to myself every time I use it knowing that it looks a million dollars and costs as much as good manners. Click to enlarge. Do I have to keep saying that?

To be honest, I'll exploit any opportunity to post a screenshot of this software. Here, it's dealing with signals on the 40m band and beyond, albeit using my single 15m (6.7m physical) element.

 

SDRUno - The most beautiful Piece of Software Ever Created?

 

Anyhow, the objective of checking and testing interoperability of all the various tech I'd gathered together for the day (which shall forevermore be known as /p0 day) was complete, and it was time to head home for tea.

More tales from the trails soon. How will a 20m element work? Will I have to employ a little foldback/linear loading? Will a small loading coil bring the 10m resonance point down, like it does on a 40m EFHW setup? Is anybody reading this nonsense anyway?

Stay tuned.

-- ----- -..- -.-- ..-.

LM317 DC to DC Voltage Regulator

Here is another project of mine.

Maybe someone will find a use for this small piece of kit.

There are a few spare PCBs available, and I can provide a schematic to go with it if required.

Regards,

Alex

M0TOT

LM317 under test

 

Should anyone wonder why non-radio articles appear regularly in our 'Feature Articles' section, let me refer you to the MSARS constitution:

The aims of the Society shall be to further the interests of its members in all aspects of Amateur Radio and Electronics.

and Alex is one of the most prolific contributors of articles on electronics projects.

Here is yet another of his creations. This time he has shared a very useful looking generic stepper motor and driver circuit, for which I can immediately think of a number of real-world uses.

Unipolar stepper motor and driver circuit

A note on unipolar and bipolar stepper motors

Unipolar and bipolar motors each have their own pros and cons, and the choice of one over the other is dependent on the application it will be used for.

Bipolar stepper motors use a single, large coil per winding, which creates more powerful magnetic fields than unipolar alternatives. This in turn results in higher torque figures achieved at the motor output shaft. Because the coils of a bipolar stepper motor can change polarity, this also means that all phases can be put to work at once, further increasing potential torque output. The main disadvantage of a bipolar stepper motor is the requirement for H-bridge circuits to reverse the polarity of the circuit.

Ohmic Readings, Sanyo Denki Co., Stepper Motor 103-540-0147

Unipolar stepper motors use tapped coils, of which each side can be independently magnetized. Because the current running through each coil will be running in a different direction dependent on which side of the coil is magnetised, the polarity of each phase can be reversed without reversing the current of the entire circuit. However, because only half of each coil is magnetised, unipolar stepper motors suffer from reduced magnetic force, and thus reduced torque. Unipolar motors are simpler to install and operate than bipolar stepper motors, because their circuitry does not require the use of H-bridges.

You can see the motor circuit in operation by clicking the image below. The video file is around 13MB in size.

Berni M0XYF