October Meeting – Report

In change to the published programme, we heard two short talks given at very short notice by Ken G3LVP and Giles G0NXA.

Ken G3LVP described some his experiences operating while on vacation in Spain.  He mentioned that one of the increasing problems in holiday locations, as in  many urban locations here in the UK, is the increasing noise level from electronic equipment in the vicinity.  During his latest trip he found HF conditions poor but did manage to work a small number of DX stations.  He was surprised to hear only a  few G stations, commenting on the almost complete lack of “big-gun” G stations on the bands – he surmised that perhaps they only appear when a rare DX station surfaces or when there is a major contest.

Giles G0NXA told us about his recent visit to the RSGB Convention at Milton Keynes.  He was impressed by the venue which he thought an improvement on recent years and emphasised the benefits of attending the lectures which improved his knowledge of various subjects – both in depth and spread.  He saw just two other CARA members:  Bob M0NQN and Tony G3SNN.  Giles said he was already planning to attend next year and urged other member to do likewise as it’s a great event.

Derek G3NKS

September Meeting Report

“One of the best talks for a long time” was the flavour of many comments heard following the CARA meeting on 17th September.  At that meeting we heard John 2E0GCR relate the story of his trip across the Atlantic in a rowing boat!  Needless to say not any old rowing boat but a special purpose one designed for the trip.

The boat was designed to hold a full crew of eight but they set off, towards the end of 2014, with just seven, reduced after a few days to six when one crew member had to airlifted off due to a severe wound infection.  The video clips of the airlift were exciting to say the least with the helicopter crewman swinging violently on the end of the winch cable as he tried to land on the boat.

John described the hardships encountered, eg a diet of mainly curried meals and during the night of being hit in the face by flying fishing appearing out of nowhere.  There were compensations such as the beautiful night sky complete with shootings stars – no street-light pollution to spoil the view in  mid-Atlantic!

A very interesting meeting which held our attention throughput and to judge by the seemingly endless number of questions one which provoked much curiosity and admiration of the crew’s endeavours.  A full report on the meeting will appear in October’s CARA News.

Unfortunately, because of the great interest in John’s talk, there was insufficient time left for the second part of the talk on Smith Charts by Giles G0NXA, so this will be rescheduled for another meeting.

Many thanks to John 2E0GCR for such as fascinating and enthralling talk.

Derek G3NKS

August Meeting Report

At a well attended August meeting, Giles G0NXA introduced us to the basic principles of antenna matching and the Smith Chart.

smithchart-audience

Giles explained that we need to match the antenna to the feeder for three main reasons:

  1.  to maximise power transfer,
  2.  to minimise the SWR (standing wave ratio) on the feeder so as to avoid power fold-back or shut down by (solid-state) PA protection circuitry,
  3.  to minimise power loss in the feeder (which can occur with a high SWR).

He then went on to talk about complex impedances, how they can be described and measured, and concluded with a description of the Smith Chart as a method of solving matching problems by graphical means.

Another very good club meeting, with lots of interesting and useful information being presented.  Many thanks go to Giles G0NXA for giving us the talk and for presenting the information in  a readily understandable manner with many tangential stories to illustrate the points he was making.

Many thanks also to Peter G3YJE for yet again manning the tea/coffee bar – volunteers for future months would be most welcome.

Derek G3NKS

July Meeting – Restoring an Air Ministry T1154 and R1155

This month we had a very interesting talk by Tony, G3YYH, who is working to restore an Air Ministry T1154 transmitter and T1155 Receiver, or, as I tweeted at the time;

The radio was designed in the late 1930s, around 1939 it went into production at various manufacturers, with production continuing throughout the war.

Around 75,000 R1155 were produced, Tony tells us

I can’t tell how old mine are, but I’m fairly sure the R1155 is an early one because it has the early tuning knob that W/Ops hated and was therefore replaced

Tony discussed the various issues with restoring these radios, from difficulty finding suitable screws (apparently BA or British Association aren’t hard to find, but new ones aren’t dirty enough) to lack of spare parts.

Because so many were made, it was common for hams, and other  hobbyists, to butcher the radios for parts, or even just to get a good box. Sadly there were some guilty parties in the room.

As these radios were designed or, and used in, aircraft, they have some interesting and unique features, such as a Morse key specifically designed to be immune to vibrations, and not produce sparks, as the operator would be sat between, and often in, the aircraft’s fuel.

The radio would also be directly connected to the aircraft’s internal headset system, and as Tony doesn’t have a whole Lancaster in his shack, he’s had to produce his own.

Tony’s radios are mostly in fully working condition, although no one replied when he called CQ in voice, or CW

And finally, for those who like to see the inside of things…