10 Metres Opens Up For Early Sporadic-E Openings

It would be worth keeping an eye open on the 28MHz band over the next few days. The band was open for some very strong sporadic-E contacts across Eastern Europe as far as OK & SP and down into southern Italy as well as DL and OZ plus south westwards to EA yesterday (13 May) and also today (Friday 14th) from noon until late afternoon.

One notable SSB QSO was with Raphael IM/P- IK0FMB (what a callsign!!) on the little island of Antioco, 20K West of Sardia with an S9+ signal with 400W to a 2-ele home made beam who gave me a 5&7 report with 400W from my windoim antenna.

There were quite a few low power beacons to be heard including IZ8DXB/B in JN70L as far south as Naples and EA4Q in Spain. Stations on 28 MHz were reporting that 6M was also open although when I listened a bit later I heard nothing on my windom.

Lets hope that this early opening is a foretaste of good DX conditions this summer on the HF Bands as the sunspot cycle progresses.

73, de Derek G3GRO

Dayton 2010 day 1

This is the first of a series of mini posts describing the trip to the 2010 Dayton Hamvention. G3VLH, G4ANN, G3LHZ, M0ZAF and myself (G3YSX) traveled out to DAY via Charlotte yesterday. Looking at the various blogs, we did better than many other European hams who tried to go out yesterday, but none the less it was a long haul. We got here, but it seems that those that tried to travel out via Spain found that flight after flight was canceled.

In our case the flight was delayed from 0940 to 1140 due the late arrival of the inbound aircraft, which was in turn caused by an extended flight to dodge the ash. Our flight time increased from 9 hours to 11 hours due to the need to fly north of the volcano to avoid the ash.



From the aircraft we could see the volcano off the port side of the aircraft.

We finally landed at 16.56, 3 hours 20mins later than planned. We were then moved on to the (late) 19.49 flight to DAY in a process that was very smooth by US Airways. We then arrived at Dayton field just as a thunderstorm settled in. A bit of bumpy air and a short hold gave the pilot an opportunity for a slightly expedited landing just as the storm moved to the south of the field.

Getting the hire car was smooth, but navigating the extensive roadworks put our GPS sat nav into a routing loop. We told it to use minor roads only, which did the trick, and finally got to the hotel at 23.30. For me this was a total journey time of 21.5 hours.

Stewart/G3YSX

MTI ATU2000 / STR400

Richard, G4ANN, is looking for information on an Automatic ATU that he is hoping to repair and use on HF. The label says that it is made by (or at least Marketed by) Marine Technology International Ltd. It has markings STR400 and ATU2000 on the cover.

Outside and internal pictures are shown below.

If anyone has any information on this ATU, particularly a circuit diagram and/or a manual of some sort, please can you email (stewart at g3ysx.org.uk), or add a comment on the blog.

Thanks in advance for any help

Stewart/G3YSX

VHF NFD. The Presentation.

They say a picture paints a thousand words. Well here are two pictures that are the result of literally thousands of man hours over several years.

Peter G0VVE and Andy G7FWE clearly capture the mood at the award ceremony held before the RSGB AGM in Bedford this morning.







See you all on the hill at 15:00L on Friday 2nd July.
Or on the air from 14:00Z on Saturday 3rd July.

CARC Spring Surplus Equipment Sale

31st March 2010

Well, we had a reasonable turnout for the Spring Surplus Equipment Sale, and there was quite a wide range of equipment to go under the hammer – signal generators, a nice HP scope, a Dymar 2-tone audio generator, frequency counters, an ERA Morse Reader, a built Howse twin receiver kit, Morse keys, drawers of components, computer stuff and other items too numerous to list. It was also nice to welcome friends from other clubs.

The redoubtable auctioneer and hammer-wielder was Stewart G3YSX, and with Richard G4ANN looking after the financial and admin side of things the evening went without a hitch. And not to forget Ted G4TTY who kept the teas and coffees coming throughout the evening.



Finally, whilst CARC takes as standard a 10 per cent commission on sales we would also like to say a “thank you” to those sellers who donated all the proceeds of their sales to the Club funds – it all helps in these difficult times!

John G3VLH

Mini-Whip with CAT5

I have previously reported on the excellent mini-whip design produced by Roelof Bakker (PA0RDT) (http://carconline.blogspot.com/2009/05/pa0rdt-active-antenna-continued.html).

Recent work on the application of the design to VLF reception has enabled the use of CAT5 (Ethernet) cable in place of a coax feed.



As Roelof said in a note to the RSGB LF reflector : "Note that the RF-isolating transformers in the signal path are not correct. I have used MCL TT 1-6 parts, rated for 0.004 - 300 MHz at the -3 dB points. The common mode chokes are not optimum, as I used the parts I had on hand. Type 75 or 77 ferrite should be better."

Referring to work on 9KHz he continues "Michael used a PERSEUS SDR, which has a noise figure of about 25 dB at 9 kHz. This is due to the fact that there is also a RF-isolating transformer in the signal path.

"It is amazing that with this not optimized set up it was possible to have good reception over a 72 km path. The actual capture area of the antenna is 30 x 40 mm single sided copper clad PCB."

"I have the parts for an optical link active E-field antenna, as suggested by Stefan. Due to other more pressing matters, I have not yet put them to good use."

It looks therefore as if we can expect further developments of this simple but very effective design.

Joze (S52AB) reports on a CAT5 mini-whip http://s52ab.jalbum.net/mw-test-2/ in which he shows a comparison between reports on a CAT5 fed mini-whip and (presumably) the same mini-whip fed with coax. My visual impression from looking at the received signals is that the CAT5 has a higher loss, although it is not clear at what frequency these measurements were taken. For those interested in LF work, Jose's main site (http://lea.hamradio.si/~s52ab/) is worth looking at.

- Stewart/G3YSX

Triax 2 Lug to 3 Lug Interconnection

At a rally last year I purchased a Keithley 616 Electrometer for a very reasonable price. Unfortunately it had a serious problem as can be seen from carefully looking at the connector in the picture below.



Investigation's on the web through up this Wikipedia article (http://en.wikipedia.org/wiki/BNC_connector) that explained all. As this says:

"Triaxial (http://en.wikipedia.org/wiki/Triaxial_cable) (also known as triax) connectors are a variant on BNC which carry both a signal and guard as well as ground conductor. These are used in sensitive electronic measurement systems, particularly of Keithley manufacture. Early ones were designed with just an extra inner conductor, but later tri-axial connectors also include a three-lug arrangement to rule out an accidental forced mating with a BNC connector. Adaptors exist to allow some interconnection possibilities between tri-ax and BNC connectors."



Unfortunately the plug shown above is very expensive, and even if I had found one I would have then had to find some cable and make the connector, which if making an ordinary BNC up is anything to go by would not have been easy, and the adapters mentioned in the wikipedia article are rarer than hens teeth. I must have searched every new and surplus connector tray at the Friedrichafen show last year, and a good few English rallies and found nothing that would work.

I was at the point of giving up and soldering some wires to the outer contacts (I thought of replacing the connector with a standard BNC, but the internal construction of the Keithley 616 made this a very difficult and hazardous to the instrument) when a friend to whom I am most grateful gave me a triax to BNC adapter.

Unfortunately the adapter was a three lug adapter and as indicated in the wikipedia article it would not mate with the two pin socket (deliberately so). After a lot of measuring and staring at the connectors we concluded that the ONLY difference between the two and three pin varieties was the positioning of the lugs and that whilst not perfect a one lug socket would work well enough (at least compared to the current situation of no mating connector). So out came the Dremel, off came the lug and on went the adapter.





Now in case you are wondering, I do have a reason to want to be able to measure the astonishingly high resistance values that this instrument will measure, but more of that at a later date.

Stewart/G3YSX


Footnote to readers, the reason why CARC shows the full URL hyperlinked to the URL, rather than the more conventional article text to URL linking is to make it easier for our editors to produce the monthly pdf version of the newsletter.