70 MHz portable in the rain

Today was the RSGB first 70 MHz contest, and the weather was forecast to be overcast and dry. I operated from the SNBCG contest site at the Secret Nuclear Bunker Kelvedon Hatch.

The Icom 7300 and homebrew 6e beam was used in the field, and the Expert 1.3KA provided 160w to the antenna.

The pump up mast provides 10m elevation, and the bunker location has good take off in most directions. The only issue is some local noise when you beam towards the cellular mast that is on site.

Unfortunately the weather had other ideas, and it soon became apparent that sitting outside alfresco was no match for the British weather. The addition of an umbrella helped for the first shower, but the rain radar soon confirmed more was to come.

I decided to pack away after 90 minutes operating, as the weather was set to get worst. I also noticed a very high noise floor when both in and beaming towards the rain.

Sadly an early close meant not too many worked, but its the taking part that counts 🙂

Thanks to Dave M0YOL for his help setting up and taking down. Claimed score online, best DX GW0GEI at 314 KM

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Portable with Essex Ham

The weather looked reasonable, so @essexham suggested it would make a nice afternoon for a ham based meet up at Gallywood Chelmsford.

Essex Ham is a virtual club, great for like minded local hams to meet up and experiment. I opted for my usual setup, 12m fibreglass pole and a 4m slim jim antenna.

The slim jim is a tried and tested design, and made from 450 ohm ribbon feeder, although other designs are available. The antenna can be rolled up and easily transported to site.

Portable Equipment

50 Ah Portable 12v battery

Icom 7300 and 12 m Push up pole and Slim Jim antenna

It was interesting to work G1NOX Mel in Dartford, M6OVN/P Glyn near Winchester, M1ECC Dave in Basildon, M0FAQ Martin in Great Notley and G7UTB Jim in Rochester.

Glyn M6OVN/P was 72 miles away, not a bad VHF contact.

Various poles with people trying out different antenna configurations.

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MF and HF RX Antenna Splitter

I was looking for a simple project to split a RX antenna into two receivers, my Wellbrook loop feeds my Kiwi SDR and also my HF radio.

The Wellbrook loop is very capable at LF and MF frequencies, and so makes a great alternative for RX on 472 KHz and even NBD reception should my local noise allow.

The RX slitter was originally found as a PDF credited to Todd VE7BPO, but had later been refined by Dave G4AON. The project uses 2x FT50-43 ferrite torroid and 100 Ohm resistor to match the output to 50 Ohms.

The addition of 3 x SO239 sockets (or sockets of your choice) and a suitable box will see the project come in around £5. Unlike some of the cheap CB style splitters, this will be 50 Ohm matched.

Thanks to George M1GEO for helping with the construction.


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70 MHz Cumulative #1

This was our first opportunity to go portable VHF this year, making the most of a very warm February afternoon.

The RSGB run a series of contests thought the year, and this was the ideal opportunity to put on the club call M0SNB. We operated from the Secret Nuclear Bunker near Kelvedon Hatch, using the Icom 7300 and 160w from the expert 1.3KFA solid state amplifier.

The antenna was my hombrew 6e for 70 MHz, this is built onto a 4m boom, that breaks down into 2x2m for easy transport to site. I have detailed the antenna build project in this article.

The weather was so good we decided to operate alfresco at the bottom of the 10m pump up mast.

Here is George M1GEO operating with the Icom 7300 and Expert setup on the operating table.

Dave M0TAZ operating the station.

The contest lasted for 2 Hrs, and we managed to work 48 stations all over the UK.

All together an enjoyable contest, thanks to everyone we worked.

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Exploring Network Radio with the Android 7S Plus

Network Radio is VOIP and not traditional RF radio, but it does share a number of things with traditional radio. Starting with the software, Zello provides a channelised platform and this has been adopted by amateurs to provide a starting point for activity.

The software can be downloaded on your mobile phone, tablet and computer by visiting Zello.

You can access these channels by searching for Network Radios and looking for this logo. Channel 00 to 06 provide general chat, you can call CQ and listen on any channel. Every user must be registered and approved by a moderator before you can speak in the groups, but you can listen without any further delay.

The system uses PTT (simplex) communication, so sounds and feels like traditional radio. If you have a mobile or tablet you probably want to set up the PTT toggle ON so you can take your finger off the screen while talking.

Like traditional radio call CQ, wait and see who comes back and have a chat! It could be someone local, or on the other side of the world, a bit like DSTAR or DMR via an internet gateway.

The audio quality is excellent compared to DMR and DSTAR, nice clear and punchy audio without the retro hiss and crackle of analogue systems.

I opted for a Network Radio (mobile phone with PTT button) and selected the 7S+ Android phone with 2 SIM slots and the device supports 2,3 and 4G. Some of the very cheap models don’t support 4G so worth checking. It is basically a cheap android phone, but much cheaper than dropping my Google Pixel while trying to have a chat.

 

 

 

 

 

 

 

 

 

 

If you want to have a listen to the channels, audio can be switch on and off using the tabs below.

Channel 00

Channel 01

Channel 02

Channel 03

Channel 04


Channel 5


Channel 6

Receiving GMDSS messages (Part 2)

Part 1 discusses getting started, Part 2 looks at the messages received.

Many of the messages are simply “TEST” messages, this is because it is mandated the systems must be tested at regular intervals. The positive side is the number of messages being exchanged is quite high, and so it doesn’t take long to record traffic.

In this example, you can see a number of test messages being sent too and from both ships and land stations.

Taking the top message as an example, you can see this has come from the ship KAVAFIS with its unique MMSI number 256821000. The database provided by John GM4SLV allows you to click on the name of the ship “KAVAFIS” and this allows you to see further information.

You can also review the location of the ship, usually derived from Automatic Identification System AIS data.

The main purpose of the system is to assist with the safety of life, and so you will receive emergency signals sent from or relayed by ships.

Using the database provided by John you can query all the urgent / distress calls received in the last 24 hrs using this query.

If you haven’t already seen it Part 1 deals with getting started.