Monday, April 23, 2012

Sinclair Spectrum - 30 Years Old!


In 1982 after a lot of thought and constant mind changing I bought myself a Sinclair Spectrum 48k Computer. At the time I had looked at lots of other machines including the 'Oric', 'Dragon' and 'Lynx' computers, but was finally persuaded (rightly) by a friend to go for the Spectrum. The best thing I ever did! When I bought it Sinclair dropped the price of the 48k machine by £50 to £125....so off I went to W.H.Smiths to buy one. I even took some time off work expecting a huge queue, but no, only me. I asked the girl expecting that they had already sold out, but she smiled and went to get one. YES!!! I couldn't believe it...off I went to take it to work to try it out!

Now instead of writing more, this guy says it all, so I am quoting this from his blog... Thank you Michael Hanlon...you have said it all!

The Sinclair Spectrum - 30 today

"If there is something guaranteed to make a 47-year-old chap feel old, it is to be told that the first computer he ever got his hands on is 30 today. THIRTY! That’s how long ago Clive Sinclair released his groundbreaking ZX Spectrum home computer, a machine that was the future, once. And like millions I bought one, at the rather grand price of £125.

This was the bizarre false dawn of home computing, when a slew of standalone machines flooded the market, all mutually incompatible, incapable of being networked without some serious soldering and bought by people for the most part unaware of what to do with them. And nevertheless, we loved these strange gizmos which you plugged into the telly and required software to be downloaded via a cassette deck.
The Spectrum was far cleverer than most, and came in a natty black case that shrieked ‘Year 2000” and had a clever (and, crucially, cheap) rubberised one-piece keypad. It was the iPad of its day, well-made, hugely desirable and very stylish; I remember queues in the shops and fawning news items about this British marvel. This was a rare industrial success story at a time when unemployment was at a postwar high.
But what was it for? Playing games, that’s what. Yes you could buy a printer but I remember the results came on shiny four-inch-wide paper and no one pretended this was any kind of serious business machine. But at its heart lurked a fairly powerful processor (by the standards of the day) and a stripped-out operating system that allowed young and clever programmers too work wonders, creating innovative games with colour 3D graphics and wrestling every last pixel of resolution out of its primitive graphics hardware.

It is probably down to machines like the Spectrum, its predecessor the ZX81 and the Tangerine, an even more basic computer, that Britain led the world in the lucrative computer games industry (it is not widely appreciated that mega-successes such as ‘Grand Theft Auto’ are, despite their American ambience, as British as Wallace and Gromit. If you could program a machine like a Spectrum then you could program just about anything, and a whole generation of young programmers took full advantage.
Sadly I was not among their number. I had some friends who mastered the intricacies of machine code but my brain was just not up to it. I played other people’s games on my Spectrum for a year or so then the thing was packed away neatly in its box and forgotten. I have no idea what happened to it.
The early 1980s was an odd time in the computing age. The technology had advanced to the stage where machines that could fit on a table top were cheap enough to be sold to the public, yet there was no real computing architecture to support a true IT revolution. It was as though someone invented a car in a world where there there were no roads. You turn on an iPad and it’s all there – the all-powerful, all-singing Interweb, so intuitive now that five year olds have no problem. But turn on a Spectrum and you got a white screen – and a cursor. The fact that anyone managed to get the thing to play Space Invaders and the like was something of a miracle. I believe someone even managed to connect a Spectrum to the Internet once; the poor old thing must have had the shock of its life."

I can go one further than this...I did use my Spectrum on the primitive Internet and I also used machine code to programme it!

Saturday, April 21, 2012

Topband Transmitter F.G.Rayer

In 1970 just before I got my Amateur Radio licence I built my very first transmitter. The circuit came from Short Wave Magazine and was produced by F.G. Rayer G3OGR. My first attempt was built on an aluminium chassis and my Dad made me a front panel out of mild steel. At the time Neil, G3ZPL had built the same circuit and it worked great! The circuit consisted of an EF91 valve in the VFO and another in the buffer. The Power Amplifier (PA) was a 5763 valve which could run about 15 watt input.

The AM modulator consisted of a 12AX7 (ECC83) and 6BW6 amplifier.


After spending weeks of painstaking drilling, filing and soldering I finally got the transmitter to work, but it had a problem. The VFO seemed to react with the PA. When I tuned the transmitter to the antenna the VFO would pick up spurious signals and shift up the band! Although I had an OA2 stabiliser valve this did not solve the problem. Maybe this was caused by the power supply dropping in voltage when the PA was taking more power.
Later I borrowed my transmitter to George G3ZQS and his antenna got hit by lightning which welded together the vains on the tuning capacitor! Not to mention the Power Supply which 'blew-up' - one of the smoothing capacitors exploded leaving a permanent dint in the roof!
When I got my licence I rebuilt the transmitter with a screened VFO in a separate aluminium box, and an aluminium front panel, this worked really well and was completely stable. The modulator used an ECC83 which had a high gain, I seem to remember using an ECC82 which had a lower gain, but same valve pin configueration.
F.G. Rayer produced loads of circuits and designs for transmitters and receievers in the 1960's and 70's. Almost every month had a design from this guy in Practical Wireless, Short Wave Magazine or Radio Communication. Most were variations of a theme and at the time he was the Enid Blyton of radio. I have to admire Francis G. Rayer, his designs were always well written and easy to follow. I recently found out that he also wrote science fiction books!
Thank you G3OGR!

Wednesday, April 11, 2012

432Mhz HB9CV review

Having used an HB9CV antenna for 70Mhz for a while, I wondered how one of these for 432Mhz would perform while out portable up on the hills. Earlier this year I aquired a 4 element yagi for 144Mhz that is fine for portable use. This left me with a 144mhz HB9CV that I have had for years. I used it occasionally portable and before that used it vertically polarised on my mast at home.
So...what to do with my redundant 144Mhz HB9CV?
Out came my hacksaw along with some measurements and built my own little antenna for 70cms from an old 144Mhz HB9CV!
Looking at this little antenna made me think...will this really work? It tuned well on 432Mhz and during the last contest set it up on a small mast next to my car in the drive. I was quite surprised how I could hear stations that I could hear on my big yagi from the shack. I would have to wait a few weeks for the next contest to try it out proper.
Last night was the Tuesday night activity contest on 432Mhz, so I took my FT817 and HB9CV up to Winter Hill. Setting it up was easy with my window bracket and wooden base. I have to admit that I was amazed at the performance of this little antenna, I could hear stations as far away as the South Coast! I worked a few stations, but I wasn't really interested in the contest, just what I could hear and work long distance.
The HB9CV was remarkably sharp with a couple of side lobes on either side when listening to a distant station and the front to back seemed quite good. The VSWR reads about 1.5 to 1 which is good for a home built antenna!
The problem with 432Mhz antennas is that they are very sharp and we tend to have lots of elements. I used to have an 18 element parabeam, a fine antenna for fixed station and serious contest stuff, but you can miss an awful lot up there on the hills with a multi-element yagi!

Saturday, March 24, 2012

TV Times

This is so true!
In 1990 we had five channels and a huge CRT...now we have hundreds of channels a tv that you can carry under your arm!
Maybe it is time to curb all the crazy digital channels available now. I can't believe how many times I try to find a channel that has someting watchable on it. So much rubbish and OMG! how many commercials do we have to watch. I must admit that I simply don't watch television unless it has a good programme or film that I want to watch without the commercials!
When will it end!
Now, how about this...
Today my daughter had Sky installed in her house. She so pleased to have it at last! Fantastic efficiency from Sky, all documents arrived, engineer rang to confirm times, fully installed and working fine!
Then, the same day at teatime she gets a knock at the door...it's the Television Licencing Officer. "Your TV licence ran out 2 weeks ago" said the man. Then under caution proceeds to 'book' her for not having a licence. "I only had Sky fitted today" says my daughter. "Can you prove it?" he says while writing down what channel she is watching at the moment and whether he can see a digibox anywhere.
How crazy is this?
No gentle reminder, no letter through the post, no phone call or text message, but a 'baliff' at the door just 6 hours after having Sky installed. This is obviously because Sky informed the Television Licencing prior to installing and the Licencing Department seeing an opportunity to jump on a 'licence dodger' My daugher always pays her licence monthly and was up to date, but March was the end of the licencing year and they had not reminded her to renew her Direct Debit.
Technological efficiency at it's gutter level!
Why don't they go back to the old analogue days and find the real 'licence dodgers' with help from their 'TV Detector Vans'. It don't work with digital anyway!

Saturday, March 17, 2012

Auriol Weather Station

For a long time I wanted a wireless weather station with outside wind and rain sensors. I have a 'simple' weather monitor from Maplin in my room that I was given as Christmas present. I looked at the price of the complete weather stations, but they are quite expensive, then I was told about the Auriol weather stations sold at Lidl before Christmas. Too late now! Would have to wait ages until Lidl get around to put some more into the stores.
After a search on the internet I came across one for sale brand new for £20, so I bought it! What a wonderful bit of kit this is! Has wind, pressure, rainfall, dew point, outside temperature and lots of other measurements. Using this I was able to predict the 144Mhz tropo opening a few nights ago! The Auriol weather station display is very clear and has a lovely black facia, different from all the boring grey facias on the expensive weather stations. The wireless signal transmits at around 434Mhz with a distance of about 50m. It works fine in my garden.



Gosh! How things have changed. Back in 1980 I had a huge wind speed and direction monitor made of solid brass on my shed roof. It came from my Uncle Bill, who worked at the Winter Hill Transmitting Station. High up on the mast was the weather monitoring equipment. The stuff I had was taken down from the mast after being hit by lightning. It still worked fine, but the analogue electronics that came with it was incredible!
I also made a wind speed monitor myself using some brass rods, plastic cups and an electric motor. It worked, but of course the wind speed on the meter was erratic and totally inaccurate.
Eventually, I gave away the equipment to a Secondary School so that they could develop it further.

Friday, March 16, 2012

144Mhz Tropo

Last night I worked EC1AJL on 2m, here are his antennas in Spain...dream on Steve!
At last! An opening on 2m!
Since putting up my new antennas conditions have been either flat or awful. Over the last few nights I have been watching the weather maps and monitoring the pressure on my new weather station. High pressure of 1036 sitting over the country for most of the week, but then starting to slowly move to the South East. This is the recipe for good conditions into Europe! I was really pleased with myself for remembering how to predict an opening like I used to do back in the 1970's and 80's.
On Wednesday I heard several French stations and some German and Danish stations, most too weak to work with my measly 5 watts, but then later in the evening two quite strong French stations F6BGR and F1UVN were heard and I managed to work them with no problem!
Last night, the opening moved more to the South West with some quite strong stations from Spain coming through. I managed to work two stations EC1AJL and EA1FDI on the North coast of Spain!
Gosh! This was amazing with just 5 watts and a 5 element! It is something like 15 years since I have worked Europe on 2m, and I can't remember if I worked any stations in Spain!
Now i'm writing QSL cards!

Friday, March 09, 2012

G4AQB/P back in the 80's

How things have moved on! In my last post my Yaesu FT-817 covers all bands from 1.8Mhz to 432Mhz, a shack-in-a-box! Now contrast this to the same location in the early 1980's.

Here is my Yaesu FT101E (which I still have!) along with a home made transverter by Chris G4AGJ and SWR /Power meter. When I look carefully at these photos I see other things from that time. Can you see a scruffy looking Mothercare Baby Box? That was my toolbox for many years when I did field service mending televisions. I always kept it in the car! My car was a White Ford Escort and in those days carpets wre unheard of, you had to put in your own! So I cut bits of carpet left over from my front room, you can see it under the equipment. Note the RSGB sticker on the windscreen and the HUGE power supply!

Now this photo is in the back of Chris, G4AGJ's car. Chris spent a lot of time building an HF Transceiver. It covered 1.8Mhz - 30Mhz and used Plessey SL1600 circuits. It was an amazing project with it's Eddystone 898 dial and professional looking front. This inspired me to build a copy myself, but just for 160m and 80m. Again, home made transverters and power supplies.
We had a lot of fun up on Matchmoor Lane (Winter Hill) I still do, it is so quiet and relaxing just listening to stations and working them in contests.
Now we have the Tuesday night contests when the VHF /UHF bands come to life and it is time to go out there and work portable!
A thought for tonight...
We have a huge Aurora at the moment and the pressure on my weather monitor is showing 1033, surely we should have good tropo conditions and also contacts through Aurora. I listen on the 144Mhz and 432Mhz bands and there is nothing! Back in the 80's we would be working stations all over Europe. How come?