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G4SKO England flag England

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Thanks for checking out my profile. I started my Ham adventure as a shortwave listener way back in the days of valves (tubes) and AM in the sixties with various broadcast receivers (totally inadequate of course) including the famous HAC one valver which you had to build from a kit.

I still have fond memories of building the HAC single valve

 

Eventually I graduated to the No.19 ex tank set which weighed as much as a Rolls Royce. Primitive as it was, it was a revelation, again it was only AM capable but I found I could inject the local oscillator signal from a portable radio into the antenna and resolve this new fangled mode (to me) called SSB, WOW! I had arrived in the modern age.

WWII No. 19 set, not the one I owned but very similar.

Many other receivers followed over the years including the classic Eddystone 710, deaf as post on the higher frequencies and it used to drift like a stranded ship until it warmed up,usually after a couple of weeks hi hi...but great fun was had. A Racal RA17L took pride of place some years later after my Realistic DX300 gave up the ghost following repeated repairs and marathon listening sessions deep into the twilight hours.

The Eddystone 710 shack heater(left) and The fantastic RA17L(right)

If the Racal wasn't such a lump I would probably still have one in the shack today. A variety of homebrew radios have been attempted, old regenerative designs,TRF recievers and a host of the vintage Practical Wireless projects started and often abandoned but some worked pretty well. All part of the learning curve and part of the journey but most of all, great fun.

My schoolboy interest in electronics and radio got me in plenty of trouble with school, spending too much time listening to daytime AM ragchews on Top band on a transistor radio I had managed to convert to 160M with a bit of guess work and blind tampering. That wasn't the end of it, home made shock machines consisting of scrap transformers, door bell buzzers and batteries secreted in my school bag, used to electrify my close circle of friends (literally). I have my science teacher to thank though, as he was the one to steer me in the right direction once he got wind of the geek who had taught himself to read circuit diagrams and the principles of electronics. A working life in various areas of electrical engineering and auto electrics followed in parallel with my ham activities, finally becoming licenced in the early eighties.

I have always had a keen interest in antennas and propagation and had some intriguing contacts via various modes eg: troposcatter, refraction, aurora and long and short path qso's with some exotic callsigns over the years on HF. The mysteries of the shotwave bands continue to unfold and confound. On one memorable occasion, working a guy in New York city on a handheld via his local 2M repeater crossbanded to a repeater in Belize and me driving along the M62 motorway running a converted CB rig with 10 watts FM on 10M, needless to say I nearly fell out of my seat.

Strange contact

Back in the eighties a friend G4MYP Terry (now sk sadly) and I used to have a regular weekend sked with Les Sampson 7Q7LW in Malawi. On one particular Saturday afternoon I was in Terry's shack, in the basement, we took turns to call 7Q7LW expecting the usual reply, nothing! called again, nothing,nada,zilch! We checked the band, it was wide open, this was most unusual, we persisted for some time but not a peep from Les. After maybe an hour there was a knock on the shack door, "come in" we said, expecting one of the local hams to enter, we were just a little surprised to find an unfamiliar face at the door. This gentleman was dressed in what I can only describe as a safari suit, now we may have been a lot younger back then but not stupid all the same and we knew there were no Rhino or big cat in Huddersfield, darkest Yorkshire.

It took us a couple of seconds to realise our unannounced visitor was none other than 7Q7LW Les. Surprise? you bet, he was back to the UK for one of his home visits and thought he'd look us up. Fantastic!!! and needless to say much drinking of whiskey ensued. He was well fed and watered during his, all too short visit and I still cherish the 7Q7LW eyeball QSL card. We lost touch with this fine gentleman of the airwaves and I understand he is back in the UK now permanently, maybe retired these days from his employment with the British Foreign Office, we never did tease out of him what his actual job was. Great memories tho.

Life, family and work pressures caused me to set the ether aside for a while but the thrill of the HF bands has never been far from my thoughts. The adventure continues and what a fantastic hobby/adventure amateur radio is.

January 2012 :-

Finally resumed my ham activity, it seems I'm just in time for decent HF propagation. 10M has been very lively (my favourite band).

My current mobile rig. Kenwood TS-570DGE

I do like to operate mobile, running 100watts from a Kenwood TS-570DGE. Antenna is the usual, loaded quarter wave. 10, 15 and 20 meters.

Summer 2012:- Finally resurrected my homebrew 2 element cubical quad for 10M. It was need of a serious rebuild. Several years up in the air and exposed to the elements has taken it's toll, the spreaders and mountings suffered substantial rot. The rotator, an old Yaesu was also totally stripped down and rebuilt, the position potentiometer replaced, this was giving errors in position. Now working perfectly. You probably gather I don't like waste or replacing equipment needlesly.

Other antennas include an off centre fed dipole cut for 40M which works OK on other bands too but is no substitute for a Quad or Yagi of course.

Below, is the now revamped and rebuilt quad being winched into position. We had to use the car to winch it into position and an extending ladder as a jin pole, quite a mission.

Below, finally back up and running perfectly Recycled and rebuilt, this time using fibreglass fishing poles as spreaders instead of wood, far superior.

2015 Update The tubular mast is now mounted on my homebrew tiltover box section mast all handled with a heavy duty brake winch, this makes it very easy to tilt over and carry out modifications and maintenance now. I really enjoyed the project and of course all at a fraction of the cost of a commercial alternative, probably tougher too.

 

This antenna often got me through pileups even with modest power. Some slight redesign with the feed now being a 2:1 balun resulting in a good SWR curve around 28.500mhz. The results are very satisfactory.

September 2013 Aquired the Icom IC756PROIII Shown here at the operating position along with the Kenwood TS-570DGE to the left, SDR receiver on the left hand monitor, Yaesu FT-857D top shelf. The right hand PC monitor handles rig control and logging, on the boom is a combination of  a dynamic mic and tiny electret for both the lower rigs. The KW-107 Supermatch ATU bottom right is ancient but is very veratile and easily handles legal limit.

April 2016 and the 10M quad has been taken down in favour of the Cushcraft MA5B. This gives me access to more bands now that we are on the slippery slope of the 11 year sunspot cycle. The Cushcraft is pretty good but not like having a mono-band antenna on 10M

 

Here's my CAT controller He's called Lemmie, he's a Scottish Fold,quite a character with his tiny folded ears and is quite adept at changing Band,Mode and VFO settings just at that crucial DX moment but we love him all the same.

April 2017 and a bit of a glitch

Yours truly suffered a serious heart failure epsiode. To cut a long story short it resulted in me having a triple heart by-pass which was followed by a small stroke during my hospitalisation followed by pneumonia and a pulmonary embolism, hey! why do things by half.

Anyhow my recovery is going well and no lasting effects from the stroke to speak of thankfully and the new pipework is working well. So what to do with my prolonged time off work, around six months is projected.

Enter my linear amp rebuild: My recently acquired, secondhand Ranger linear amp had been fitted with new 811A valves/tubes, these were great until 2 of them lost there emissions and resulted in a 50% power loss. Now was my opportunity to rebuild and modify the amp to accommodate a Russian tetrode and what follows is an outline of the project:

Here's the Ranger 811H which utilises four 811A valves it was in a poor state when i bought it via an eBay seller and I was dissappointed that 2 of the four new Taylor valves failed. Maybe they are just rebadged Chinese valves?

Here goes Step 1. Remove the old valves and bases.                   Step 2. Make a new base plate.

The GS-23B Russian metal ceramic tetrode seen below was chosen to replace the old valves. It has  a 6.3 Volt heater and altho I only have around 1.7KV of anode voltage to play with it was decided that I would be able to realise about 1 Kilowatt output with careful biasing and given that the legal limit in the UK is 400 Watts this would give me plenty of headroom.

The GS-23B has coaxial screen grid and cathode connections so I had to find a way of fabricating some form of mounting arrangement. One solution would be finger stock but that is difficult to source and hellish expensive in the UK, so some lateral thinking was required.

Step 3. Coaxial mounts, these are made from rings of heavy guage copper wire and the finger connectors are automotive inline blade fuse holder contacts. This one is for the screen grid and will sit on top of 4 x 100pF chassis mounted feedthro caps. To the right is my first mock-up attempt, later changed to the full ring version seen on the left.

.

Step 4. Screen and Grid supply transformer. 240 Volts and 110 Volts was chosen as a starting point and the cheapest method was to locate a suitable shaver socket transformer, this has an isolated 240 Volt winding and a 20VA 110 Volt winding. Perfect!

Step 5. Blower, screen and grid control. A PC snail fan shifts plenty of air seen here to the left. Screen bias at 350 Volts and Grid bias which will end up around -18 Volts both derived from the shaver tranformer and Zener controlled MOSFETS the first rough circuits are seen to right below. These were later modified in the final version.

Step 6. The Tetrode mounted and the chimney fashioned from a ceramic plant pot. An object of great beauty!

Random chassis bashing

And Finally Here she is, re-badged as the Ranger GS-23B the only one in existence. Early results are very promising. So far I've pushed her to around 600Watts into the dummy load and once the final biasing and removal of the protection/sacrificial resistor are complete I'm confident that 1kw should be possible. The testing of the signal purity is very encouraging and I'm looking forward to many years of useful service

Although I have summarised the mod here in 6 steps I can say that there has been quite a bit of work to arrive at the final amplifier. I really must thank Pete G4TCB our local valve guru for his encouragement, boundless knowledge and experience for guiding and sometimes badgering me during my recent illness. Without his skill, time and assistance this would not have happened. Cheers Pete!

See you on the bands. 73.

Mark G4SKO

8329200 Last modified: 2017-09-13 22:43:45, 15576 bytes

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DX World Award#3086
Granted: 2016-01-03 08:45:02   (G4SKO)

Endorsements:
  • 10 Meters Mixed
Grid Squared Award#3345
Granted: 2015-02-15 13:50:02   (G4SKO)

Endorsements:
  • 10 Meters Mixed
World Continents Award#3499
Granted: 2015-02-14 12:30:04   (G4SKO)

Endorsements:
  • 10 Meters Mixed
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