Archive

Archive for August, 2016

Making Waves -Boy’s toys – the DJ-G7

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Something new arrived in the postbag the other day – an Alinco DJ-G7 three band handheld transceiver.  Operating on 2m (145MHz), 70cm (433MHz) and 23cm (1296MHz) plus a wide RX scanner from 0.53MHz – 1299.995MHz although it is bblocked on the cellular/mobile phone frequencies for obvious privacy reasons.

Anyway, I unboxed it, fitted the battery (Li-Ion) the hand strap and belt clip and turned it on to see what it could do.  Obviously, the battery wasn’t fully charged so any transmitting would have to wait but, on tuning through I did manage to pick up some nearby PMR stations which seemed promising.  It also came with a nice desktop charger which I made use of and was surprised at just how fast it charged the battery.  The manual states that using the supplied charger the battery can be charged from flat in 3 hours, I made the initial charge in about one.

Personally I live in a very bad place for VHF amateur radio, let alone UHF so I was pleasantly surprised when I sat the DJ-G7 on the coffee table the next morning, scanned through 2m and voices suddenly erupted from the speaker.  It was G4VUA (Alan) from the next village running a local(ish) net.  I picked up the set and called in and, lo and behold, he replied to me.  Not bad from a little handy sitting in the living room.  All things considered though he does have an advantage of height above me.

Anyway, how clean is the signal?  I tuned it to 1.2965Ghz and with only the supplied rubber antenna fitted, checked the output against my spectrum analyser.  The results were spot on – a lovely clean signal with no harmonics detected.  Well done Alinco – this one looks like a winner.

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Moving on to other matters, conditions both on HF and VHF have improved of late.  There have been numerous sunspots appearing and this has led to some late summer sporadic e propagation on both the higher HF bands (15, 12 and 10m) and the VHF bands of 6, 4 and 2m.  I suppose this was ideal for this weekend which was the Worked All Europe DX Contest.  However, myself, I made a few CW contacts with EO25UA, EO25UD, ZS9AZ and EM25HQ to name a few.  I also collected a few contacts on JT65.

Also, a friend of mine – Stefan, DO2JAX, has been operating from a holiday location as OZ/DO2JAX.  After a week I managed to work him yesterday on 14.317.5MHz.  H ewill be active from this location until the 19th August so, if you hear him, give him a call.  He is only operating SSB but can be found on all bands at different times.

Till next time.

73 DE M0CVO

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Making Waves -LoRa and Patch

 

Due to one thing and another it seems that I have not had a lot of time on my hands to do much radio activity for a while.  The sun was spotless for some time during the month of July and conditions on HF literally bottomed out.  Luckily this all seemed to change in time for the IOTA Contest on during the weekend of 30 – 31st July.  Suddenly there were spots on the sun a decent MFI and all bands opened – right up to 2m.  There were intercontinental contacts to be had throughout the HF bands up to and including 10m (28MHz) and quite a few 6m hops although these were probably more down to sporadic e’s rather than multi-hop F2 Layer propagation.

Anyway, during the month I have been experimenting with antennas for 23cm (1297MHz) and 13cm (2321MHz).  I have looked at various designs from the double quad antenna, More details of which can be found HERE to the slot antenna, which can be read about Here and the IFA Patch Antenna, which you can read more about HERE.  I finally settled on a version of the IFA antenna as this was easy to etch onto a piece of single sided PCB with an FR-4 backing.

Mini VNA readings of 23cm IFA Using MiniVNA Tiny to determine properties of 23cm IFA Antenna.

Once I was happy with it I 3D printed a case for the antenna to fit into and checked that the VSWR readings remained below 1.5.

IMG_20160724_125958 IFA Antenna in 3D printed case.

I also looked at the Vivaldi antenna details of which can be found HERE which would make an interesting broadband antenna that could be used to feed a dish, but decided against it at present.

On Friday 26th July I was lucky to receive notification that I had won a pair of RF Solutions LoRa modules in an online competition.  I promptly received these on the Saturday and set about trying to work out what to use them for.  They are effectively a voltage controlled pair of transmitters/receivers and can be encoded to work as remote controls, provide remote networking, remote switching or act as remote sensors.  The range is up to 16km using spread spectrum technology at 868.5MHz.

CocRLbSWAAA2P4B The RF Solutions Ltd Gamma LoRa pair

I am currently experimenting with them as a remote wireless sound activated switching system.  More details on this at a later date.

CorSENhXEAA2w8b Sound Activated wireless switch..