Tuesday, 30 April 2013

Martlesham Microwave Round Table (MMRT) and RSGB HQ visit

The Martlesham Microwave Round Table event has become firmly established as a spring event, notionally held on the last weekend of April. On those odd occasions that Easter falls on the last weekend of April, then MMRT will be held the weekend before Easter.
The 2013 event was held last weekend ( 27 and 28th April).

Kent, WA5VJB/G8EMY is a regular visitor at MMRT. I picked Kent up from Heathrow last Thursday and drove back home via Bletchley Park, where Kent had a lunchtime meeting with the CEO of one of the several companies based within the confines of the park.

After that meeting we met up with Martin Atherton, G3ZAY, and Kent delivered around 50 'tubes' to him for use in Colossus. He had been busy around Texas, collecting the various valves needed by Colossus . These include type 807s, which Colossus seems to go through in large numbers, according to the curator of the museum. This is the second delivery of American tubes that Kent has made to the museum, and all at his own expense. He has now been honoured with his own photographic entry badge to the Park. Well done Kent!

On our way back home to Felixstowe we then stopped off at RSGB HQ in Bedford in order to collect the Trophy (see last blog) that I had been awarded at the AGM. I had asked Carlos to take it back to Priory Business Park for me, so that I could later collect by car. I had been told it was probably too heavy and awkward, in its protective wooden box, to carry back on the London Underground. I wouldn't want to damage it, with its distinguished history of previous winners.


Although this is not the first time I have been to the 'new' HQ and therefore knew what to expect, never the less I was again disappointed at seeing the building that is now the Societies' home. No reception area, nowhere to buy books or other RSGB 'trinkets' and no efforts at welcoming members, domestic or overseas. As poor as Lambda House may have been, it did at least have a reception area. Kent was not too complimentary about what he saw!

I realise that the RSGB has been through a few very financially-tight years, but we are told that the Societies' finances are improving and since the 2007 economic downturn, business property rentals have reduced to the point where I am sure the Society could afford a bigger and more inviting HQ. RSGB is, after all, a member Society and should make some effort at providing for members to visit. ARRL HQ, W1AW, is a really interesting place to visit, if you ever get the chance. RSGB could take a few lessons from ARRL in this, its Centenary year.

I'll have more to say about the MMRT in the next blog.


Picture of Colossus at Bletchley Park

- Posted using BlogPress from my iPad

Monday, 29 April 2013

RSGB 1962 VHF Committee cup

I am extremely pleased to mention that I was awarded the RSGB 1962 VHF Committee Cup at the recent RSGB AGM held at the IET in London. The cup was awarded to me for '....preamp design at 70cm and above'. This recognises my work on the VLNA that can be used at 70cm, 23cm, 13cm or 9cm. Many of these preamps have been shipped around the world and for 23cm and 13cm it is currently ( maybe) the most popular EME preamp design.
It would be remiss of me not to mention WD5AGO and W5LUA whose original design I built on and to RW3BP for his work on extra source feedback applied to my original VLNA that helped to improve its performance. Thanks guys!

The list of previous winners includes, but is not limited to:-
G5DT in 1962
G3NUV in 1963
G3RPE in 1966
G4PMK in 1995
G3SEK in 1992
G3FPK in 2000
There are a lot of winner callsigns and names inscribed on the cup.
The trophy has not been awarded every year.

I feel truly honoured to have my callsign and name inscribed with so many notable winners of this great trophy.

Out of interest I may try to research the contributions of some of the previous winners and publish the details on my blog.

73 de Sam

- Posted using BlogPress from my iPad

Wednesday, 24 April 2013


Still preparing for the Martlesham Microwave Round Table this coming weekend.
The registration site has now closed. There are around 100 names and callsigns on the list.

There will be a grand raffle draw on Sunday with over £500 worth of prizes on offer, including a modern signal generator to 4.2GHz, Funcube Dongle +, VLNA 23cm preamplifier and a USB power meter.

There will also be the usual test equipments for measuring noise figure, gain, match etc. I have also just finished boxing a 10MHz Rubidium reference so that the test equipment can be frequency locked ( where appropriate).

There are 7 talks during the two days of the event. Details are on the event web page accessed through www.microwavers.org ( click on the event link).

Amongst our overseas visitors this year are WA5VJB, F2CT, PE1BTV and PA7JB?

A full report on the MMRT event will appear in Scatterpoint, the newsletter of the UK Microwave event.

- Posted using BlogPress from my iPad

Saturday, 13 April 2013

Shack move

The cold winter weather convinced me that I should do something about my cold shack. Even with heating on it was difficult to a achieve higher than about 12C some days. Clearly, this is far too cold for any serious operating, building or testing. I will be adding extra insulation ( already have double glazing and 18inches of roof insulation plus insulated dry lined walls!) but not until later this year.

I have looked at the possibility of operating from inside the house for a number of years. In fact every time it gets too cold to work in the existing shack! Clearly, remote control of the shack would be necessary.

These days there are lots of ways to operate a remote shack from the comfort of a warm room in the house. In general this would mean using a wireless or wired LAN.

I was unhappy about using a PC to control and operate any of my radios ( K3, TS2000X, FT817, FT7800, IC207). I much prefer to have the radio in front of me. The cost of a pair of Remote Rigs and an K3/0 or RC2000 was regarded as unjustified.

An additional problem was that I also wanted control of 9 microwave band transverters & PAs, the main rotator and the possibility of 23cm and up EME, with control of dish azimuth and elevation. Controlling that lot would require a deal of effort!

Since I don't have any requirement for operating beyond the boundaries of my own property it made more sense to look at some alternative method(s) of remote control than using full control over the internet as others have done.

A quick solution, suitable for HF only, was to run a single 30m low loss coaxial cable from the outside shack into the house. In my case I had two suitable lengths of FSJ4-50 and FSJ1-50 available that were both able to reach from the front room of the house to the cable cabinet outside the shack. From there is was easy to extend the long cables into the shack and onto the cable frame where I could interconnect with the existing antennas, transverters and PAs. The cable enter the house through a neat 50mm hole drilled in the house brick wall, and terminated inside on a diecast box with two back to back panel mount lightning surge arresters. The box is earthed to a copper earth spike outside the house. Another connector will be added to the box in due course, if required.

The FSJ4-50 is the main cable and is used to extend the HF antennas to the indoor shack. The smaller cable is suitable for extending the K3 or TS2000 2m to the shack where it can either connect to the transverters via the existing remote switch or to the 2m masthead preamp and shack-located 2m PA for 2m operation.

It is also possible to connect the K3 via the indoor 4m transverter and extend the antenna connection over either of the coaxial cables to the shack where the 4m PA, with low noise preamp, is located. Finally the low loss coax can be used to extend either radio's 6m antenna connection to the mast mounted 6/4m dual band yagi for 6 or 4m operation.

All this still requires that the rotator be controlled remotely, of course. Here control over the home WiFi is used in preference to extending the control cable into the house.

My rotator is a Yaesu G1000DXC. In order to control this an ERC USB/RS232 remote control unit is plugged into the G1000DXC 6-pin mini-DIN and connected to the shack PC. Control is in conjunction with a suitable application, such as PSTRotor running on the shack PC. Using Logmein the shack PC can be remotely controlled, and hence the rotator, from an indoor laptop or even an iPad.

Remote control of the transverter switch is still under consideration. I am currently leaning towards control with DTMF on 70cm at low power using the low power on-premises control privileges that we are allowed. This would also allow me to switch PAs on and off etc.

Control of the EME dish is more straightforward as long as all that is required is simple moon or sun tracking since the control application (Moonsked) can also be accessed by Logmein from the indoor shack. However, anything other than simple control, such as 'nudging ' to track moon noise will be a bit trickier and a solution is still being worked on.

I will update the blog with details as the project progresses.

In the meantime it is nice to operate 40 and 15m, using the 40m dipole, from the comfort of the indoor shack. No more expeditions to the cold, windy, wet, north pole!

- Posted using BlogPress from my iPad