ARRL 28MHz Contest

With the sunspot cycle still humming and 10m lively during the week, it was time to plan on being active during the ARRL 28MHz contest.  I actually planned in advance for this one and had the vertical up and tested prior to it going dark on Friday.  I even played with the tapping point on the torroid to improve the match.  I’m getting more practiced at getting the Spiderpole mast up in the garden and the top of the pole was at 50 feet this time and it was visible over a far greater area!!  Excellent – time for a beer or two.

Propagation predictions indicated that the band would open at about 0700 and die at about 1800.  So on Saturday morning I was on the band at 0715 and had my first QSO.  When I called the second station the computer crashed – and I mean died – no blue screen of death – just dead !!  To cut a long story short I was getting an intermittent high SWR on the vertical and I assume the resultant RF in the shack was bombing the PC.  So the vertical had to come down.  It turned out to be a whisker of coax braid flapping around in the breeze so it was easy to fix, but it probably cost me a few hours.

Conditions were quite different to the CQWW a few weeks ago, or maybe it was that there are far less expeditions for this event.  Saturday was spent searching and pouncing on CW, mainly Europeans in the morning as I'd missed any chance of the DX to the east sorting tha antenna out, and then the band opened up well to the States in the early afternoon.  As predicted the band died just after 1800.

On Sunday I was up at 0700 again and managed to work a few stations to the east – VK, JA, BV.  But I always seem to miss out to the east and I failed to work 9V, JT, NH2 and VR.  I tried a few CQs during the morning but never seemed to get a run going.  There was one exception when I held a frequency for about 40 minutes and worked 50 stations.  Then a loud Russian with an appalling signal CQ’d in my face so that was the end of that.  Then conditions went strange for a while with multiple echoes on both Far East signals as well as some of the nearer European ones which made CW copy very difficult.  At 1pm I seemed to have worked most of the stations on CW so I had a play on SSB for 90 minutes.  (This was mainly due to the antique ARRL rule that says assisted single operators go into the multiple operator mixed mode category - so you may as well pick up a few multipliers!)  I think that I have now remembered why I hate HF SSB contests!  Later the path opened up well to the US and it was easy picking them off.  Then, at around 1700 (an hour early?!), just when I was homing in on my self imposed QSO target, the band fell off a cliff and died.

So the numbers:

(Remember this is 100 watts into a vertical – no beams – no linears !!!!)

CW      435 QSOs

SSB     62 QSOs

So I just missed the 500 total target.

Countries          69

US States         46 (inc DC) – with Alaska, Hawaii, Idaho, North Dakota and Utah being the elusive ones.  In total I worked 255 VE’s and W’s.

A total operating time of just over 13 hours for an average of 38 Qs/hour.

A very enjoyable event and probably the last one of these for a number of years.

Logger32 gets a rig control panel

Maybe I missed it before, but I think that this is a recent facility.

 The picture below shows a screen capture during CQWW-CW.  Logger32 is on the left hand screen and N1MM and DX Atlas are on the right hand screen.  Both Logger32 and N1MM are communicating with the K3 via LP Bridge.  This allows the use of both the DX cluster on Logger32 and the Reverse Beacon Network on N1MM to find new stations and multipliers.

Previously I used K3-EZ to control functions on the K3, but that consumed valuable screen estate..  OK, you could actually use the K3's front panel (!!) - but that would be too easy.

Here is an enlargement of the new Logger32 radio control panel.  You can programme up to 36 buttons.  It is easy to programme the macros such as:
$command MD2;BW0270;$ - to get USB with 2700Hz bandwidth
$command SWT19;$ - to "tap" the ATU tune button
$commandSWT13;SWT13;FT1;UPB7;RT0;XT0;$ - to get a split "UP5".  i.e. copy VFO A to B, enable split, set VFO B 5kHz above VFO A and set the RIT and XIT to 0.  This probably needs a command to enable the SUB receiver but I haven't done that ---- yet.

CQWW 2013 - CW

Wow !!!!  28MHz is still humming.  I decided to do a 10m single band entry as the band is only open from 7am (ish) until 1800 (ish) and it doesn't trash the entire weekend.

After the SSB leg, I decided to put the end fed vertical up again.  However I got deflected on the Friday and ran out of daylight.  So the antenna wasn't up until 10am on Saturday morning and I lost about three hours there.  I managed to get the vertical somewhat higher this time and the base was above the house ridge line with the top at around 45 feet.

Well in about 12 hours of operation I worked 374 QSOs in 91 countries and 28 zones for circa 108k points.  I never did decide whether I was country hunting, trying to achieve maximum rate or maximising the score.  So I probably failed on all counts.  All operation was search and pounce so an overall rate of 32Qs per hour isn't too bad.  Only one all time new country was worked - Honduras, but my 10m country score benefited considerably and now stands at 148.  Another 21 countries were heard and called but not worked due to pile-ups and conditions.  These were CT, DU, GI, GW (!!!!), EL, EU, FJ, J8, OA, OH0, OM, OY, OZ, PJ7, TF, TI, YN, ZF, 3V, 9M2 and 9M8.  So had I had a strategy it could have been a 100 country weekend.

And it gets better!!  I got up early on Monday morning prior to taking the antenna down and managed to bag the XZ1J expedition for another all time new country.

Portable in the back garden (again!) - CQWW SSB

As conditions had been humming on 28MHz throughout the week, I decided to concentrate on that band.  While the usual doublet antenna sort of works, could I do better within the constraints of time available and space?

 I had experimented with half wave end fed verticals during one of the Pacific DXpeditions a couple of years ago with very mediocre results.  I now believe that was due to the cheap "fibreglass" mast being either lossy or conductive. 

So this time the 20m Spiderpole (not at full extension!) was used.  The bottom of the antenna is in the plastic bag above the tree line in the top picture at about 20 feet..  The matching circuit was thrown together at the last minute and was based on the parallel tuned circuit used for the last attempt on 18MHz.  The torroid now classes as "unknown type!" and had 16 turns on it with a two link winding - the 8:1 ratio mentioned in many articles.  For the available variable capacitor this was way too much inductance so the winding was reduced to 10 turns.  This allows tuning from below 14MHz to above 30MHz which makes for a good general purpose tool for future experiments.  Links windings didn't work well to provide a good match so using the network analyser I tried a number of tapping points to get a good match.  This was somewhere between 1.5 and 2 turns.

Does it work? - WOW !!!!  On longer paths it was 2 to 3 S points better than the doublet.  On nearer European signals it was better on most signals.

Due to lack of time, and a failure to get up early enough on Sunday for the Far East, I was only active for about five and a half hours.  All operation was search and pounce - there is no point me calling CQ in an HF SSB event with 100 watts and a wire antenna!!  The band was full from 28.2 to 29.2 MHz.  I worked 201 stations in 45 countries.  North and South America produced excellent signals, though for some reason the Caribbean signals were rather weak.  Even a number of W7's were worked which is normally a black spot for me.

Bring on CQWW CW and the ARRL 28MHz !!

RSGB Convention

I spent two days at the RSGB Convention this year.  Most of the time was spent manning the RSGB Contest Committee stand with a steady stream of visitors.  Due to the RSGB "policy" of issuing multiple conflicting programmes, I unfortunately missed the talk on surface mount construction.  However, I did just manage to get into a very packed room for Sam's talk on his new 70MHz transverter - very impressive.

However, the main reason for attending was to collect the Surrey Trophy for winning the Open section of VHFNFD with the highest ever overall score.  Rather than attending the formal dinners, the Pembrokeshire Contest Group and the Tiverton (SW) Club organised their own dinner at the Shoulder of Mutton - just up the road from Horwood House.

The Surrey Trophy winning team of: Martin, GW3XJQ; Nigel GW0IRW; Peter GW4VRO; Tim G4FJK; Irene; Dale G3XBY, me; Stewart GW0ETF; Steve GW0GEI.  Unfortunately Gordon GW6TEO could not attend.

"Portable" in the back garden

I never got my act together for the 4m Trophy contest and I haven't got an antenna at home.  So ....... time to erect a temporary antenna.

This is the G0KSC 6m/4m 4+4 element design carefully modelled and tweaked to work with 9.5mm tube elements rather than the original 12.5mm elements.  Seen here on a 20 foot scaffold pole surrounded by houses and trees.  GB3ANG was audible throughout the weekend.

The contest started with a band with Sporadic-E into eastern Europe.  In the first hour 8 QSOs were made into HA, OK, S5 and 9A.  Tropo conditions were average and certainly favoured those in the North.  Forty one contacts were made in the first 4 hours and then the antenna was removed to make way for the BBQ !!

VHFNFD - WOW !!

To celebtrate the RSGB Centenary the Weather and Radio Gods got together to produce a spectacular VHFNFD.  Clear blue skies and the best conditions I've heard on 70cms for many a year.  I provided the 432MHz station for the Pembrokeshire Contest Group in IO71OP.  Again this was a single operator experience involving all setup, operating and tear down.  The two new HA8ET preamps worked flawlessly and, given the strengths of some of the DX, definitely improved the performance of the system.

Conditions were excellent into SW France and Spain throughout the event and into PA/ON/DL/OZ/LA during the Saturday evening.  In all 199 QSOs were made into 54 squares with an average distance of 501kms.  The best contact was into JO62 at 1207kms and there were 31 contacts >900kms.

It could have been much better but interference from the 144MHz station lost the majority of the first four hours of the event.  Then to cap it all, I got 200 yards out of the field and suffered a front tyre blow out.  Where is the jack - that would be under all the kit you have just packed into the Land Rover!

Homebrew PCB - do theory and practise agree?

Two years ago I was arm twisted to provide the 432MHz ststion on VHFNFD for the new Pembrokeshire Contest Group. I could write a book on the trials and tribulations of resurrecting a system that hadn't been powered up for probably ten years plus. One challenge was to turn it into a twin system transmitting into two antenna arrays. This required an unequal power split as the two PAs needed different power levels. After some frantic last mninute experimentation, a coupled line power splitter was made by hacksawing some copper board to make the two lines and supergluing them to an earth plane - it worked remarkably well. The split was about -11dB. The design was created using the coupled lines model in QUCS. Roll the clock on two years - can we do better in terms of a power splitter?  A lower split of around -8dB would be nice, but would that be physically possible with very closely spaced lines? The design was done in QUCS, implemented in DesignSpark and then the board produced using my homebrew UV exposure unit. The design called for lines 12.5 thousands of an inch apart.

 

The interesting part was just how long it took to etch the narrow gap between the lines.  I normally reckon about 90 seconds to etch a board.  It took a further eight minutes to etch that fine gap.  Looks good but does it work?

The impedances look good on the network analyser but sadly the coupling is about -11.5dB.  I nor actually believe that coupled lines reach a limit at around this degree of coupling.

I will try the old hacksaw produced version and this rather better looking version on the VHFNFD site to compare performance.  But an interesting exercise to use two software packages and the home PCB facility to produce a nice looking product.

ADSL drop outs caused by 80m - cured ?

It took a while but I finally realized that the sporadic multiple ADSL drop outs coincided with the 80m club championship contests!! The "short - term" cure was to turn off the router during these events!! It took even longer to find a cure. Various ferrites had no effect but by a process of elimination the pick up was on the telephone line input to the router. Interesting given that the telephone feeds in this area are buried. Though a colleague did a professional study on this a few years ago and reports that the attenuation to buried cables is less than 10db. Finally I built the ADSL filter described by G3VMW at here

.

I haven't had the chance to measure it - but - it works.  According to the router statistics the line attenuation has gone up by a dB and I may have lost 500kbps on my line rate, but I can now run 100 watts on 80m without any drop outs.  In the past 10 watts clobbered the router.

Power Relays for 432MHz Mast head Preamp??

HA8ET for his new masthead 144MHz preamp uses miniature power relays rather than expensive coaxial relays to save on costs. He claims to be able to run 1kW without frying the preamp. Correspondence with Gyula revealed that he hadn't tried the same technique on 432MHz !! So can it be done? The relays he used appear to be obsolete but the RT114012 is a close equivalent. Initial tests on a rats nest lash up showed an through loss through two relays of about 1.3dB and a return loss slightly worse than 10dB - not good. !!  So what happens if you at least try reasonable construction techniques?

OK - thrown together and that track probaly isn't 50 ohms.  But ..............

The through loss is now down to just under 0.3dB and the return loss 15dB so its "nearly" there.  The isolation to the RX port is only 18dB but that is to be expected - and there will be a second relay shorting this port during TX.  A "Mk1 screwdriver short" gives an isolation of just over 40dB.

Unfortunately this is now tantalizingly close and would save having to remove two CX120 relays from a power amplifier!!!

The blog is born

Today is May 14th 2013. I said I'd never have a blog. But here it is ........