Digital Modulation talk

Digital Modulation by G0RVMWho would be interested in a 3-part talk about digital modulation principles?  Its aim is to provide a foundation from which digital techniques such as PSK31 can be better understood.

The talk starts with the most basic form of digital communications – on/off keying, progresses through Frequency Shift Keying then onto Pulse, Phase and Amplitude Shift Keying.

The talk will identify some basic formulae to help understand the different modulation techniques and include question and answer sessions.

If you are interested please respond by leaving a reply.

Andrew
G0RVM

Sale or Wanted Corner

At risk of starting a trend on the site……. I’m in the market for an HF mobile rig preferable with a detachable head and ideally if possible either yaesu, ICOM or similar (e.g. yaesu Ft100D or ICOM 706 etc).  happy to look at other models if available. Looked on Lynch line, WS, Navada, Ebay and the usual but a few not many around (couple I’m bidding on). Wasn’t going to do HF mobile but…..decided I might give it a try whilst the shack is WIP.  Open to offers and happy to negotiate a sensible price to pay.

 

Feel free to reply to the post.

Thanks Mark

 

Kempton Park Rally

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A few hours later and reasonable journey with a few roadworks encountered and overcome later we arrived. Cup of coffee to start the motor and off we went. Andrew met his friend so went off exploring as did John and I and vowed to not spend much. Yea right!!  Usual players Moonraker, ML&S, Icom, Yaesu etc etc on show with Waters and Stanton having quite the lions share of space – always good for a browse. John and I found our way to the bits and pieces stalls and bought some minor electrical items (ferrite rings amongst other things) few pence. I was drawn to a mobile antenna system on sale from an independent (can’t remember the name) that on-paper looked impressive but…on closer inspection would probably last 5 mins compared to Hustler or Diamond and the build quality was pants. Resisted that.

Then….went back around again to the smaller stalls and to the small club bring and buys and there it was. An old home brew antenna part built and in need to some TLC. In true car boot fashion asked for a price and couldn’t believe what i got back. £2!!! Yes £2 and we think although needs a close look not done that yet that its a J pole design and according to the club selling it off they seem to think it resonated well somewhere around 145.250-146.000MHz but may have done better elsewhere. So I have my project and with the help of John (M3EQQ) and John (M0HFH) I’m sure we can make it perform with a few mods along the way. Happy bunny!! Especially since we think a few others had seen it and were after it to. Also had an aluminium tripod for £8 but again resisted.

Here she is (folded up of course and currently in the old office/shack);

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I was not alone.. John also bagged a bargain with a Yeasu Ft7800 (I think) for £110 in the rally bring and buy although yet to hear that it performs but seem to be quite tidy. Andrew purchased a mobile mast I think for the field trip and we finished off by looking around once more at the radio’s on offer, new specs and whats coming up.

We finished off talking ourselves into the merits of Total Mast Solutions and Andrew and myself will certainly be investing as it seems an all encompassing and impressive system easy to use and portable in that the system (depending on the model and we were told there are over 100 now) can be broken down and re-assembled to suit the operating conditions, antenna systems etc. Bespoke builds are also possible.

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Then….

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We then found ourselves heading back to Lynch’s and a refreshing cup of tea (and chocolate mini rolls!! excellent marketing tactic well worth the visit!). On a technical note Andrew found his new power supply whilst John and I miandered around the shop and as always I got pulled back to the many antenna systems on offer and in consultation with Andrew have yet again changed my mind on the main system at the new home QTH shack.

A thoroughly good day and well worth the trip. I came away with some ideas/thoughts and perhaps even proposals for future PR events that the club might want to consider and of course my bargain. I’m planning a visit to the Weston rally on May 17th  to see what a smaller scale rally might look like so will be reporting back on that in due course.

Excellent day I believe had by all. Looking forward to the next.

Mark M6KMJ

Kite Antennas

The Thornbury and South Gloucestershire Amateur Radio Kite Club had its inaugural meeting today at Whale Wharf where a number of kites were trialled. The testing was inspired by a recent talk from Roger G4ROJ. We also had a go at aerial bombardment (video on application).

A number of members brought their own kites.

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Rex’s Sled Kite

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Peter’s Box Kite

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John’s Kite

 

Part of the testing was to establish the lifting capabilities of the kites. Rex’s kite was connected to a 5 litre can of water. After emptying a couple of litres out the kite was able to lift it easily.  A second test was carried out with a length of 2.5mm2 wire to form a vertical. It was found that the vertical obviously needs to terminate under the kite.

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Field-day Weekend. Update 2

On Thursday April 9th, Rex, John and Andrew went to view the field that the TSGARC will be using for its three-day extravaganza.  It was such a warm, sunny day that we could not resist the temptation too do some portable work in addition to just looking at the field 🙂

40m DipoleWe arrived about 1530hrs and were quickly on the air and making contacts across the UK despite the skip being a little longer than anticipated at that time of day.  Andrew brought along a 10m mast which we used to support a full-sized 40m dipole in an inverted ‘V’ configuration an IC-7200 HF radio plus the all important generator.  After spending some time on 40m we raised a 20m dipole from the same mast and then worked 20m for a while.

The image to the right shows the 10m mast and 40m dipole situated toward the S.W. end of the field.

Later in the afternoon we had some unexpected visitors: Rob, Andy and Dave somehow found us!  Was our signal that strong!  We stayed till dusk then packed everything away and went back to Rex’s house for tea and hot-crossed buns.  Nice 🙂

Andrew, Rex and RobEveryone was impressed by the size, location and RF quietness of the field despite some large overhead power-lines in the adjacent field. It will make the perfect spot for our three-day portable event.

To the left, Andrew, Rex and Rob man the temporary station setup on a plastic patio table…  The black box to left of the picture is the Palstar manual ATU.

Andrew
G0RVM

Field-day Weekend. Update 1

Hopefully we are all aware that the club is running a 3-day portable operating weekend  between May 23-25th.

Planning is underway and we have a large field with a good low-noise floor, large tents and some masts, antenna’s, radio’s etc.  So its starting to come together.  But we need your help to make the weekend a success.

Please see this communication for further details.

Andrew
G0RVM

Time Signals

WWV 20MHzNIST, the American National Institute of Standards and Technology are responsible for many things but one service which as radio amateurs we may associate to them is the broadcast of time and frequency information 24 hours a day from their radio station, callsign WWV, in Fort Collins, Colorado.

The information broadcast includes time announcements, standard time intervals, standard frequencies, UT1 time corrections, a BCD time code, geophysical alerts and marine storm warnings.  The transmissions are in the HF part of the radio spectrum and are powerful.  Transmissions on 5, 10 and 15MHz are at 10kW and 2.5kW on 2.5 and 20MHz.  Its worth noting that transmissions are DSB with AM modulation.

In the UK we can hear these transmissions depending upon time-of-day, ionospheric conditions and frequency.  They are RF frequency precise and thus can be used to check the alignment of a receiver amongst other things.

Recently WWV has started transmissions again on 25MHz radiating 1kW from a monopole.

For more information on WWV, including its history, images and a FAQ click here.

Have a listen on precisely 5, 10, 15, 20 or 25MHz and see what you hear 😉

Andrew
G0RVM