Year: 2019

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

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.

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.


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.