Date : Tue, 10 Aug 2010 19:51:31 +0100
From : andrew.hancock@... (Andrew Hancock)
Subject: Free Stuff Tranche III [Results]
CBers - call is SWR, but it's really VSWR! (spent many hours in the lab,
working on transmission line experiments and reflections!)
It was just the governments way of making money with another stealth tax, CB
license, TV License, and Dog License!
But very few bothered with two of them, and they couldn't be policed, so
were canned!
Two out of three of them gone, and TV License to go soon as well hopefully!
Burner:- legal if your Licensed, and if you are licensed, you can also use
other frequencies as well.
Yes, there was also stupid stuff, like if you installed you aerial on the
roof, you needed to attenuate it by -10db, most CD radios, had this switch
fitted,
but very few used it!
Skip - Sun Spot Activity - 12 Year Cycles!
-----Original Message-----
From:
bbc-micro-bounces+andrew.hancock=cyrus-consultants.co.uk@...
[mailto:bbc-micro-bounces+andrew.hancock=cyrus-consultants.co.uk@...
9.co.uk] On Behalf Of Rick Murray
Sent: 10 August 2010 19:11
To: bbc-micro@...
Subject: Re: [BBC-Micro] Free Stuff Tranche III [Results]
On 10/08/2010 19:07, Rick Murray wrote:
> changes in SWR. Never used a burner, but did use a half-wave. Thank God
> the UK took its own set of freqs, for the CEPT channels were often full
> of Latinos (sounded Italian to me, but I may have been wrong). 27MHz,
> in Somerset. Either ~'93 was a damned good year for skip, or they were
Upon rereading, it occurs to me that this might read like gibberish, so:
SWR:
Standing wave ratio, I think. Little meter like a satellite finder that
hooks between your CB and the antenna and measures, I think,
reflections. Because too many reflections back, or maybe reflections too
strong?, could damage the CB's output transistors. Annoyingly, the SWR
depends upon frequency, so you need to tune either for best results on
your favourite channel, or best results across all of the channels.
Don't forget for GB/CEPT use, this means two sets of frequencies!
Burner:
Legal CBs output a miserly 4W. In open land, this might get you 5-10
miles. In a town setting, it'll get a mile and a half across Bridgwater,
but drops off quickly the further you go. Depends on the weather, the
phase of the moon...
If you want to blast your signal to the moon, you'll need a "burner"
properly known as a "linear amplifier", which can accept your CB's sucky
4W and spit a couple of hundred watts. It might have some application in
places like Texas where you'd need a burner to communicate from one end
of your farm to the other, but in a place like the UK... [they're
illegal, too, in case it wasn't obvious!]
Half-wave:
The length of a CB emission from peak to peak is something like 11
metres. In order to "not cause interference to aircraft communications
and radar", the legal limit to a CB antenna was a little over a metre.
This being a big chunk of government balls as it was later found that a
?10 ratio is about the dumbest length they could have chosen, but hey,
it was in the Maggie Era when everybody hated everything except
themselves... This goes into harmonics and such and big heavy books have
been written on the subject. Anyway, a half-wave is a big metal tube
about five metres in length.
I heard the restrictions were going to be eased to permit half-waves
(omnidirectionals up to ~6m). Did this happen?
Freqs:
27MHz. 40 channels, FM (AM and upper/lower sideband not legal).
CEPT ("PR 27 GB") freqs are:
26.965 MHz - 27.405 MHz split into 40 bands. Same as USA.
Older UK-specific ("27/81 UK") freqs are:
27.600 MHz - 27.990 MHz split into 40 bands, 10kHz spacing.
Chernobyl:
As for my comment about pumping out the RF, if 4W gets you around 4-10
miles, how much power is necessary to get a fairly clear signal in
Somerset from a transmitter in Rome (or pick any other Italian city, it
makes little difference). Remember, radio decay is logarithmic.
Oh, and if the wildfires reach the Chernobyl exclusion zone, all that
lovely radioactive crap will fly high into the air, pollute us all over
again, and...
http://www.heyrick.co.uk/blog/index.php?diary 100606
[second heading, you'll know which]
For what it is worth, those little PMR walkie-talkies provide CB-like
behaviour ( < a mile in a town to 4-5 miles in open ground) using 500mW
of power, operating 446.00625 MHz to 446.09375 MHz (eight channels with
12.5kHz steps) and they don't need a licence. The end of CB? But, then,
some could argue that CB died a nasty death after "Smokey And The
Bandit" was released. ;-)
Best wishes,
Rick.
--
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...
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