29 Apr 2012

More 10m DX and some Es

500mW 10m WSPR results - ZS6BIM best DX
Today I ran my 10m WSPR beacon at 500mW into the wire halo antenna. Conditions were quite reasonable with some good DX reports. Later there was a first sign of sporadic-E propagation around Europe - a sign of things to come for the next few months. I did try beaconing at 50mW for a little while but propagation had deteriorated so no reports were received this time.

28 Apr 2012

Amateur radio history DVD?

The ARRL has produced a DVD recently on the history of amateur radio in the USA over the last 50-60 years. See http://www.arrl.org/shop/The-ARRL-Film-Collection/ .  I wonder how much material exists on old film and video in the UK/Europe and whether there would be enough to make a DVD on the history of amateur radio on this side of the pond?

As I mentioned a few years ago, there was (once) a 78rpm sound disc made by G5UM of the last night of UK operation on the old 56MHz band back in the 1940s, but this appears to have been lost. Although there have been several books on the early history it would be wonderful to find and collate old film material on amateur radio in Europe.

Win XP PC - a full restore?

My main Windows XP laptop PC is now around 6 years old. It has a small 32GB hard drive and my own files occupy around 8GB of this, yet the PC says the C drive has only 3.8GB spare. There is a small back-up partition (about 3GB) and the rest must be program files and Microsoft bloat accumulated over the years. I've already done defrags several times and deleted all the files I know are safe to delete. CCleaner is also regularly run to sort out registry issues and I have compressed files where possible. McAfree anti-virus seems to do a decent job of keeping out the malware.

Although I hope to invest in a new PC soon, I'm considering doing a full system restore back to original factory settings in the hope of recovering all the lost/wasted space.  A full restore will need a few days of work to reload updates (SP2/3 etc) but there must be a lot of unnecessary rubbish there which would be cleared by a full restore.

My plan is to use this "old" PC to run WSPR and some VLF programmes and use a new PC for everyday tasks.

Apart from the usual back-up of any photos and data that are important, does anyone have any advice before I go ahead?

Better 10m conditions

Today I put my 5W 10m WSPR beacon on for a few hours during the day and was rewarded with reports from CX, PY, 5Z4, 4X, LB and G stations. Conditions appeared better than I have noticed in some while and this is proved by a look at recent sunspot activity. See http://www.solen.info/solar/ .

26 Apr 2012

Google Drive (bye bye Dropbox issues)

With the introduction of Google Drive, an online storage facility, I can at last overcome my issues with Dropbox and my VLF grabber. With Google Drive one can store up to 5GB free and more for a fixed price. With the PC or Mac add-on, the drive appears as a file(s) on the computer into which documents can be saved in the normal way. These then appear/sync on any PCs when you sign in to Google Drive.

The bonus is that you can make any file public and get a URL that others can go to. This means that a saved .jpg screen shot of a VLF grabber can be saved to a unique filename on the PC which then is visible to the world if they know the URL. From a webpage I can point people to the URL and they can see the screen grab as it is updated regularly.

I could do all this with Dropbox until about 4 months ago when it started playing silly and refused to sync on my WinXP PC complaining of a registry issue. Despite trying all sorts of recommended fixes none worked and I gave up on Dropbox.

In the coming weeks I will be mounting a more permanent E-field probe which will be connected to the PC whenever it is running and the VLF spectrum view(s) will be available on my sub-9kHz website.

25 Apr 2012

Email questions

As my blogsites and websites attract quite a few visitors, I get a good number of emails from people asking me questions about my projects/thoughts. Whenever possible I try to respond to these right away but occasionally, for example when I am on holiday or have filed the email in the wrong place before answering, I don't reply. Please accept my apologies and write again if after a week or so you've not had an answer.

My standard answer when people ask advice about my circuits is that they are never guaranteed and some experimentation will be needed in any particular implementation layout. The circuits worked for me and should for you if you are prepared to "tweak" values a little.

24 Apr 2012

50MHz UK Activity Contest

This evening I have been listening (and having a few 5W QRP QSOs) in the RSGB 50MHz Activity Contest. This is a good opportunity to find out how effective my wire halo in the loft is. Well, I have worked the locals (G6UW, G3PYE/P and G4BWP) and managed a "QRZ the CW" from G3MEH about 50 miles away. I suspect the results would be several dB better with the halo further up in the air co-located within my 10m halo on the external mast.

Elecraft KX3 production ramp up

Elecraft KX3 units are starting to make their way into customers' hands now, although the initial product rate has been quite low. On the KX3 Yahoo Group there have been a few reports of initial huccups although this is to be expected in any new production run and, as always, Elecraft has handled these very well. According to Wayne Burdick, production is soon expected to ramp up now these initial problems are being ironed out. Wayne writes:
"Off the top of my head....  We had one unit with a dead MCU clock crystal (extremely rare). One radio wouldn't turn off because a mic wire was touching another component (we're looking at heat shrink for that). Two had problems with EEPROM due to a firmware bug I found and fixed at 1:30 AM on Monday morning. This firmware is already in beta test. 

Mostly just new-product syndrome. We really are on the verge of serious shipping increases."
 I have still to decide if/when to order one. The initial reviews on www.eham.net have been excellent.

18 Apr 2012

Low cost rotator

In my search for a low cost rotator for small and lightweight VHF/UHF yagis I see that Conrad Electronics UK sells an "external TV rotator" for £52.99, plus postage from Germany with a free 2 year warranty.

3 core cable, 70 secs 360 deg rotation, 45kg load, 300Nm bending moment, 21.6Nm torque.  See eBay item 180832166179.

Does anyone have any experience of this rotator?

16 Apr 2012

Rotators or big wheels

There was a time when a small rotator capable of turning a modest 2m yagi could be bought for around £40 but there appears to be little available now below £300. The low cost Yaesu rotator (G250?) appears to be unavailable now.  I was thinking about erecting small beams for 6m, 2m and 70cm and was wondering about suitable rotators, but am rather put off by the costs.

A better alternative may be a big wheel antenna with around 3dBd gain omnidirectional, or more if two are stacked. 5dBd is at least as much gain as an HB9CV without the worry of a rotator.

Elecraft KX3 leadtimes

As a potential buyer (still thinking about it), I asked the sales desk at Elecraft what sort of leadtime I could expect if I placed an order for a fully loaded , ready assembled KX3 in the next couple of weeks. This was the reply:

Thank you for your inquiry and interest in the KX3 Transceiver.  Orders placed now will ship in 90-120 days. We are working hard to make it less than that, but right now that is my best estimate.

Thank you,

So, 3-4 months wait currently.

Homebase-6 (50MHz halo)

Homebase-6 50MHz halo prototype indoors ready for tests
This afternoon I had a go at scaling my Homebase-10 (28MHz wire halo) down to work on 50MHz. I simply scaled the dimensions by 28.3/50.1 (the ratio of the centre frequencies) and performance was almost spot on with a low VSWR in the DX part of 6m. So far I have only tried it in the shack holding the antenna in the air by hand and keying the TX to measure SWR. Next stage of tests will be to erect it in the loft space before erecting a more permanent version within the 10m halo on the top of the mast at the back of the house at a decent height. Still, a promising start. In the end I may opt for a small 6m beam like a Moxon or HB9CV though.

UPDATE 1600z : I have now erected this horizontally in my loftspace although it is more triangular than square. Match is good so I'll see how it performs locally next.

UPDATE 2100z: I am surprised that I'm unable to copy the more distant UK 6m beacons such as GB3BUX and GB3RAL which use horizontally polarised antennas. I need to monitor for longer to see if they appear by MS or tropo.

Winter projects review

Back on Jan 4th this year I put a list of projects that were on my "to do" list on the blog. As winter is now over it is time to review progress (or rather lack of it):
Lightbeam RX. The aim is to detect the GB3CAM 481THz optical beacon at a distance of 32km from my nearest highspot.
Well, the RX has been improved considerably and is now very sensitive and is capable of NLOS reception, but I have still to make a successful reception of this beacon.

Light beam transceiver. Following on from (1), this will either be a transceive head with a transverter or an FM transceiver that I can duplicate so I can talk to others who can borrow the second unit.
This has not progressed at all. It is still my intention to do this.

Rebuilt VLF earth mode beacon transmitter. In a few weeks time I will be able to put out a stable signal on 8.97kHz  (the usual VLF test frequency) rather than 8.76kHz. My intention is to rebuild the whole beacon TX so I can run 10wpm CW, QRSS3, 30 and 60 modes as well as WSPR.
 I have recrystalled and tested the existing beacon for 8.970kHz but the full rebuild has not happened.

Improved LF loop and E-field probe antennas. I want to erect a more permanent external antenna for VLF and LF grabber work and mount these away from the house.
Improved E-field probes have been tested but I have not erected these externally.

Case up the 137kHz transverter. This has been a rat's nest on a piece of copper laminate for too long!
Still to be done.Not started.

28MHz WSPR transceiver based on a 14.060MHz crystal doubled in a DSB direct conversion transceiver circuit.
Not started and now unlikely to be done.

In my defence, I  have done a few other projects including some 160m transmitter and 160m loft antenna work and quite a bit of experimentation on the 481THz kit although few products at the end of this. I want to do one more thing very shortly and that is to erect a 50MHz (Homebase-10 style) wire halo either in the loft space or on the mast outside in time for the Es season.

In summary, I think one can say I am what my mother-in-law called a "fireside fusilier": I'm always gunner (going to) do this and gunner do that!

My old 2m AM rig

This morning, whilst clearing out some paperwork I came across this old B&W photo showing my 2m AM transceiver from the mid 1970s. It had a tunable RX covering 144-146MHz using a free-running VHF VFO (perfectly fine for AM use) and a crystal controlled transmitter; if I recall correctly, it had a few crystals that could be switched. The TX put out around 500mW of AM and was based on the PF2AM transmitter by Pye Telecom, a project I was involved with at the time. It was built in an aluminium box covered in wood effect Fablon.

The rig was also used for CW, goodness knows how, by having an external BFO held near the rig to demodulate a CW signal. Drift was a major issue on CW as you can imagine! Using this Heath Robinson arrangement I had a weekly sked with G5UM some 80km away every Monday night for several months and regularly received 559 using an HB9CV antenna in the loft.

The rig worked some useful AM DX across the UK with the best DX from home being a station in northern France one evening but it was really used as a local natter box in the Cambridge area.

When the ubiquitous Liner-2 2m SSB rig appeared I managed to buy a second hand one and this homemade AM rig was abandoned. I cannot remember what happened to it. It is nowhere to be found, so was probably taken apart for bits, which was a pity. Today I still use 2m AM from time to time and it remains a perfectly acceptable mode for local contacts with very simple kit.

15 Apr 2012

KX3 reviews on eHam.net

There are now 4 reviews on www.eham.net for the new Elecraft KX3 QRP transceiver and the rating is 5 for every one so far. See http://www.eham.net/reviews/detail/10271. Although it is a lot of money it certainly looks one fantastic little radio. I am tempted!

There is a video walkthrough too by K2UM which is worth a look.

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.

14 Apr 2012

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.

4 Apr 2012

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.

1 Apr 2012

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.