Tuesday, 22 April 2014

Virtualnames.com

I am hoping my web access failure is just due to a temporary Virtualnames web server access problem.

Sam


Sunday, 20 April 2014

What's been happening?

I've been busy assembling our new greenhouse for the last few weeks, so it has kept me away from doing much amateur radio.

However the greenhouse is now finished and this week I will be devoting to getting ready for the Martlesham Microwave Round Table next weekend.

Today the Anglia transverter boards are being assembled with the pick and place machine and reflow soldering. I hope to be able to put together a few 'kits' for sale at Martlesham this coming week.
More 2m kits will become available in the next few weeks and the 4m version will appear in the next few months.

I have largely completed the 2m documentation, but it may need refining after the next review!

I have measured 4 Anglia or Anglia-like transverters and it seems safe to say that the receive converter is achieving better than 0dBm input third order intercept when measured in the most stringent way. Noise figure is about 1.5-1.6dB with 24-25dB gain.
Transmit converter output is over 100mW with excellent IMD.
The output spectrum is really clean.

The output power can be raised to over 6W with one of the Mitsubishi RF MOS amplifier modules. I have a new PCB for this module.





Wednesday, 9 April 2014

2.3GHz

As a result of the future of 2.3 and 3.4GHz OFCOM document that appeared yesterday I thought it might be useful to see whether I needed to be concerned about interference levels to the MOD equipment at Boscombe Down. The other MOD sites are significantly further away from this QTH as not to be a problem at almost any time.
I have been running the numbers for potential interference levels at Boscombe Down on 2.3GHz  from this location. Using the G0MJW software and the simplified path model ( no terrain data) it would appear that my 100W at the feed point and 20dBi antenna ( possibly 22dBi) gives around 6dB margin over what would be required. These numbers are for a 10% exceed.
The overall loss is 205dB, dominated by tropo scatter with diffraction and refraction both being significantly higher.
The G3YGF plots in Vol 1 of the RSGB Microwave Handbook confirm these losses.
It looks like I can operate without being too concerned that I am causing interference to the MOD down in BD!

Sam

Tuesday, 8 April 2014

Anglian results

I have completed my initial testing of the new Anglian 144MHz transverter. 
I only found one minor error on the PCB, and that is easily remedied.
The receive converter performed better than I expected, probably as a result of it being housed in a screened tin plate box. Later this week the first (#1) unit will go off for independent testing. At the same time the boards are being readied for production. With luck and a following wind, the first transverter kits will be ready for sale at Martlesham, although quantities may be limited at this stage.
For sure, the new Anglian transverter will be worth waiting for !

Sam


Sunday, 6 April 2014

Back on 4m

I found a little time today to reconnect the 4m system. I was too late for this morning's 4m contest and anyway, Sunday mornings are not normally good for me as I have chores to do, like the Sunday morning shop run and usually a coffee with a couple of the local radio amateurs. All very pleasant and far better than just talking to them on the radio!
With the 4m transverter connected to the K3 and over the long coax to the outside shack to pick up the Larcan power amp and heavily filtered preamp ( necessary due to the long coax run) I was able to hear the RAL beacon but not the Tring beacon. The YU7EF dual band antenna seems to have survived the winter.
Sam


Tuesday, 1 April 2014

Dispensing solder paste

At long last I got round to firing up the air(brush) compressor and paste controller in order to use the controlled cartridge solder paste dispenser. Once I'd set everything up I was able to manually dispense spots of solder paste onto the victim PCB. Much easier on the thumb than using a manual syringe.
The components were then manually placed onto the paste spots and after checking everything was in the right place, the PCB was placed in the toaster oven and 'solder' pressed on the reflow soldering controller. 12minutes later and the board was perfectly soldered.
It doesn't make sense to reflow solder simple little boards unless there are lots of them or they use some awkward part like a QFN or DFN package.
The intention is that I will make VLNA and transverter boards available, ready assembled.

Dave, G4HUP, will be demonstrating reflow soldering at the up-coming Martlesham Microwave Round Table (MMRT) www.microwavers.org and follow the events link. 
There may even be a chance to have a go at reflow soldering for yourself!

Sam




Friday, 28 March 2014

An early look at the Anglian

Sneak preview before I show it at the monthly Codger's meeting tomorrow!

I have just completed assembling the first Anglian 144MHz transverter. The Anglian is a direct development of the Nacton transverter, but features a significantly better performance. A 70MHz version will also be available, replacing the Nacton transverter. And for those who prefer a 'real' 6m band radio instead of an HF rig with a 6m section bolted on, the Anglian could be what you are looking for!