80-Bus News


April–June 1982, Volume 1, Issue 2

Page 15 of 55


Disks, C.B. & Amateur Radio

So, the good old INMC is no more! Still, times change and we must change with them. When the club started most users had 1K Nascom 1’s and vague aspirations to 16K and Tiny Basic. Now it seems that everyone has a 64K Nascom 2 or equivalent Gemini system with disks (except me!). For a hobby machine the cost of a dual disk systems seems excessive although I recognise that the systems on offer do represent good value for money. How many home, as opposed to business users, really need the speed of disks? Maybe the best way ahead for those of us with limited resources lies with fast mini cassette tapes or the new microfloppies. I have seen no reviews of the mini cassette systems that at least two firms are selling. Have any readers tried these out, and are they practical devices? I will be very interested to try Uncle Clive Sinclair’s microfloppies on my Nascom 1. At rumoured price of about £50.00 for 100K, even the four second average head seek time won’t put me off!

I was particularly interested in Dave Hunt’s article on CB and computers. It does seem to me that he is skating on thin ice here, both legally and ethically. The Home Office definition of CB in the UK is as a ‘short range radiotelephone service’ and that is surely a reasonable use for it. All the talk about ‘burners’ and halfwave antennas is just RF megalomania. It reduces what could be a useful public service to a rat race where the ‘breaker’ with the most power can shout down others until they rush out and fill the dealer’s pockets to try and get above the cacophony for a while. I personally agree that the licence restriction on antennas is a shame, particularly directional aerials. A good beam antenna is worth its weight in watts, and owing to its directional properties, doesn’t interfere with other local traffic. Incedentally, why do people buy LINEAR amplifiers for CB? One of the many advantages of FM is that the output is constant. This means that the simpler, cheaper and more efficient class C power amp will do just as well.

Dave’s idea for frequency-agile CB for data transmission is ingenious, I must say. Presumably, the list of random numbers would have to exclude channels 9 and 19. Also, to add to the already onerous legal problems, modifying the sets as he describes would mean that they would have to be re-certified by the Home Office.

So, is that the end of the story for data transmission by radio? No! The most glaring error in the article is where Dave says ‘Amateurs are restricted to Baudot code at a maximum of 50 Baud’. Wrong! Footnote 18 to the Amateur Radio Licence Schedule states ‘Data transmission may be used within the frequency bands 144 MHz and above provided (a) the station callsign is announced in morse or telephony at least every 15 minutes and (b) emission is contained within the bandwidth normally used for telephony.’. This means that there is no obstacle to transmitting 300 Baud CUTS format. I should add that amateurs are permitted 100 Watts of carrier power at the antenna and there is no limit (apart from what your neighbours will tolerate!) on the size of antenna that you may use.

The Radio Amateur’s Exam (RAE) is not beyond the capability of any Nascom user. After all, most of us have built our own machines and know which end of a soldering iron to hold! Country wide communication on 2M (144 MHz) is commonplace and you have the comfort of knowing that you are not acting illegally or spoiling other people’s use of our crowded radio spectrum. Although the equipment is expensive, it’s also better made and more versatile. Anyway, you can always build your own gear (unlike CB where rigs have to be approved by the Home Office, amateurs just have to ensure that they are operating within the terms of the licence). Just as a final tempter, the licence is actually £2.00 cheaper!! So Dave, why not throw away your Children’s Box [Ed. – I thought CB stood for Chicken Brain!] and do the job properly?

I hope that sets things straight. I don’t want to put down Dave’s idea. At Busby’s current telephone rates it has to be a good thing, but hopping all over the jam-packed 27 MHz band ain’t the way to do it!

Keep up the good work and 73’s from
Pete Kendall (G6ADF)

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