The Titanic Radio Page

Lots of interesting information and photos about the Titanic radio room at http://www.hf.ro/.

The photo shown is from the above site (I could not link it) and shows the only known photo of Titanic's radio room. It was taken by a passenger who disembarked in Ireland.

Lynton and Barnstaple Railway

On our holiday in north Devon last week we enjoyed a ride on the steam hauled Lynton and Barnstaple Railway. This is a delightful narrow gauge line that runs through a small piece of Exmoor countryside. When the line was originally build and opened in 1898 this 1ft 11.5inch gauge line ran all the way from the market town of Barnstaple to Lynton on the north coast winding its way around the hills. It included some long 1 in 50 inclines. The narrow gauge was chosen to minimise the costs and to allow tight curves on the line. It closed in 1935. Today the line is run as a trust and only over a very short length although, funds permitting, it is eventually hoped that the whole length can be reinstated as few obstructions prevent this. If you are in this part of the west country I can recommend a visit to this fascinating little line.

This is a video on YouTube showing the line as it was in 1935.

QRP FM pedestrian portable

Today I got back from a week in north Devon where my wife and I had a holiday cottage. The weather was pretty good for the time of the year allowing us to get up onto the hugher parts of Exmoor on several occasions. With my trusty VX2 handportable I managed to work plenty of stations through various repeaters in South Wales but my best DX was a simplex QSO on 145.525MHz with G4TRA in Gloucestershire at 101km. Despite just using the VX2 and a quarter wave whip he gave me a report of 59+20dB when I held the rig horizontal. To quote Steve, "you sound like you are in the next garden". Following this contact I worked MW0ZAP simplex. Time (and batteries) prevented me trying for more QSOs but I'd forgotten how well FM simplex works when you are on top of a moorland hill with a 360 degree takeoff.

FT817 in short supply?

I am hearing repeated stories of the FT817ND being in short supply from various dealers in the UK. One rumour is this is due to component supply shortages so units are not arriving from Japan in the numbers needed.

Of course there could be another explanation: the rig is about to be replaced at long last.  It is not unusual for dealers to be told to run down stocks of the older models which will be harder to shift once a newer model becomes available, except with significant discounting (think of the iPad3).  Once a new model arrives sales will go sky high.

Now, I have no information at all, so don't write to ask me, but I would dearly love to know the truth.

2m/70cm DXing

See http://www.f9ft.com/ antennas

On a few occasions in the last year I've operated /P in the RSGB's UK Activity Contests (UKAC) on Tuesday evenings and thoroughly enjoyed them. Even with just a small halo on 2m and a 4 el yagi on 70cms I was surprised how much could be worked and the high levels of activity.

It is some years since I've used 2m and 70cms from home with a horizontal yagi and I am tempted to erect something to give it a go. I know that outside of contests activity these days is low, but it still seems like worth doing. Whether I erect a rotatable yagi or a stacked turnstyle remains to be seen. It is a long time since 2m was filled with G8 stations using FT290s, 30W linears and Tonna 9el yagis!

Right now I have other antennas erected on the 2 small masts attached to the house and it may be some months before I make changes, but maybe I will get something in the air and see what happens. As well as SSB/CW DX there is so much more to explore these days with digital modes.

Gmail Tap

OK it is April 1st but this is actually not such a daft idea http://mail.google.com/mail/help/promos/tap/index.html

Trying to see the light (very dimly)

As other nanowave enthusiasts have told me, it is very useful when experimenting with light beams at 481THz to have some sort of lab test range that allows repeatable sensitivity measurements. So, today I rigged one up.

Up on the ceiling of my "lab" I've semi-permanently fixed a standard brightness LED fed via a 1K resistor with a 1kHz tone from my 0-1MHz audio/LF generator. I can now adjust the output until the LED is only just visible to the naked eye, with difficulty,  when the room is totally dark. I then place my optical heads (without lenses) on the same spot on the workbench aiming upwards to the very very dim light. The spacing is about 1.5m. I had to check that the signal being picked up was optical and not inductive coupling from the wiring. With this setup, my most sensitive detector can detect the beam at around S2 in a pair of headphones.

I've been experimenting with the drain current of the detector FET and with optimisation of the post cascode stages of my KA7EOI head and may have made 1-2dB S/N improvement. With this test setup I can make very repeatable sensitivity measurements. However, as the tests require TOTAL darkness I have to judge the S/N by ear. My laptop could be set up outside the room with a long screened audio lead allowing Spectran to be used to measure quantitatively the S/N but I'd have to ensure the darkness of the room is preserved.  For an example of this see http://reast.asn.au/optical/Light_Preamp_Performance_Comparisons_20071119.pdf .

At least now I can do lots of initial tests at home and only venture into the field when I have good confidence in the system performance.

Elecraft KX3 - first products delivered

This email appeared on the KX3 Yahoo group today:

"I will do as I told the crew at Elecraft and help the pressure.

At 9:10 AM this morning (Sat) a nice brown truck pulled up in my drive and after I signed for it, gave me a 12"x8"x6" box that said "ELECRAFT KX3 Ultra-Portable HF/VHF Transceiver s/n 0024

Yes ... I got a call yesterday

I am hoping within a hour to be on 20 meters chasing WG0AT on his SOTA trip and putting it thru its paces on digital.

Thank you all at Elecraft ..

The game begins
You will be happy .......

Paul KB9AVO"

8.971kHz VLF earthmode test

30t loop on the ground feeding E-field probe

An 8.971kHz earth mode (VLF through the ground) test was conducted today at 1.6km and 3.5km from home. The TX was 5W QRSS3 into 20m spaced baseline earth electrodes: one a 1m copper rod at the
far end of the garden and the other end grounded to my copper hot water tank in the house.

At the RX end I was using either (a) a 30t tuned loop feeding either the PA0RDT or G3XBM tuned E-field probe, and (b) the same E-field probes but fed with a 19 inch whip instead of the loop.

Good signals were received at both locations with the loop into both probes but there was no detectable signal when receiving on the 19 inch whip into the EFPs.

It was a struggle to see the difference between the PA0RDT and G3XBM E-field probe/preamps, but I think results with my tuned drain design may have been marginally better on this test.

VLF E-field probe update

Today I compared the PA0RDT E-field probe against my own VLF design (on the sub-9kHz website) that uses an 8-9kHz tuned circuit in the FET preamp drain. To do the test I had my wife hold each E-field probe at arms length above her head in the bottom of the garden whilst I made screenshots on the PC. The S/N on Alpha beacons and 18-22kHz MSK signals is similar with the PA0RDT and mine but the PA0RDT design has a lower noise floor. So, in future I will use Roelof's design. Some measurements made by G3ZJO today compared the PA0RDT design against the narrower band VLF E-field probe by DK7FC and Eddie's results suggest comparable performance within the limits of experimental error.