UK/CEPT CB frequencies tech question based on Of364 (ofcom information statement 2006)
G Daeb
with a guy at work this last couple of weeks.
Having asked about license application forms at the local
Post Offices in town and about licensing regulations at a
local electronics shop that stocks a small range of new CB
equipment I got on-line and went to OfCom and got us copies
of the 2006 information statement Of 364, titled "Citizens' Band
(CB) radio spectrum use--information and operation" printed.
I've just been reading through it this morning and some stuff
seems not to quite add up, to me.
Its hyphenation is inconsistent where the term "type-approval"
is concerned and, as one of the instances has been hyphenated,
I am assuming that all instances should be.
But, yeah, it doesn't seem perhaps to be quite so well edited
as it might be.
And as, for now at least, we only have access to various
incarnations of the UK 27MHz frequencies - standard UK40
channel sets - rather than try to guess or infer what the reality
is, I thought I'd ask here--seeing as this newsgroup does at
least seem to be active on a basic level with some clearly genuine
CB-ers posting from time-to-time.
So okay.
History time.
The US started with a 40-channel AM system.
In order to keep the radio unit working as long as possible,
by not blowing components or overloading it to point of a
general overheat, and get the best signal encoding, setting
the SWR (standing wave ratio, the wave against which the
signal is encoded regardless of encoding method) is critical
to getting good performance.
Given different configurations of radio and antennae performed
better at higher and lower frequencies, the general practice
was to check SWR at channels 1 (the basement), 40 (the
attic) and 20 (slap down the middle); often, setting SWR is
a case of taking the average across the set.
As such it's better to have 1:1.15 across the board than
it is to have 1:1 in the basement and 1:2 in the attic.
Also, given different configurations of equipment can perform
better at the top or bottom of the band, the practice of using
19 as a calling channel in the US derived from the practice
of people optimisimg SWR at channel 20.
And to avoid the calling channel getting stamped on by SWR-ers
it was dropped down a notch.
Given how much effort those UK truckers who did international
haulage put into lobbying for any kind of CB at all in the UK -
and, with respect to HAMmers, it was the truckers not the
Amateur stations who did, as Amateurs tended not to be able
to see why on earth anyone who had not spent months building
basic circuits under the auspices of their local technical college
(NB,
there aren't many of these in the Western Isles, where the local
shop only gets a supply ship once a fortnight, nor in a great
many other of the UK mainland's more rural areas), learning MORSE
and taking series of tedious exams had any right to even think
they should be able to operate WT equipment - 19 was left as a
"truckers' channel" with 14 being the default "calling channel".
Obviously so few people bother now that those days are long
gone.
But this does come up again, like now.
So I've been looking at the frequencies for UK and EU (CEPT)
which can be combined into 80 channels.
And taking the mathematical median point of the EU frequency band
it would appear one should set one's SWR at channels 1, 40 and, er,
19.
(26.965 + 27.405) / 2 = 27.185 (which is the allocated frequency
for EU channel 19).
Is that right?
Like, why?
Taking the range as a whole 26.965 to 27.99125 the statistical
median is an inaccessible frequency (27.478125) which is not
in either the UK or EU frequency bands.
Now, we really are only talking about normal people running
normal kit in a car, so the extent to which there's going to be
a huge difference between having to trade 1:1.1 and 1:1.15 off
is nil.
If we can't get it below 1:1.2 anywhere then the kit will be going
back to the shop/s, (and that's only assuming he buys any in the
first place). And there's no question of running any more than 4W
or anything like that--he wouldn't be happy about it.
But still, assuming I end up helping SWR a 80 channel rig in,
does anybody have any advice as to which channels it's best
to concentrate on?
Otherwise, is the OfCom document OF364 right in its allocation
table for EU frequencies in the first place?
I can see there are gaps in the band, presumably to make it a
bit more difficult for anybody to build their own. But it also seems
that the actual frequency for channel 23 is higher than for channels
24 and 25 (albeit lower than for channel 26).
Is this a typographical error? a quirk of the chipset which leads to
it needing to be addressed this way in binary or HEX or whatever?
Or a "security" control device to prevent people building their own
using analogue tuners? Or a necessary workaround for how the
frequencies operate at near the borders of various EU member
states and other countries?
One last thing: we've been watching CB prices on E-bay by way
of his mobile phone. And no matter how low they start at, they
almost always seem to end up higher for used kit, with you then
having to pay carriage, than you can get brand-new kit with a
full 12 month warranty on it from the few dealerships there still
are on the high street.
I'm all for recycling kit, but really, I can only recommend people
check the prices on the high street first--particularly given how
much scope there is for the one you get off E-Bay to have been
blown somehow or other by some berk you'll never meet...
I hope my questions make sense to someone, and that I've set
them out in a logical order.
Thanks in advance for any genuine, insightful and well-informed
replies.
G DAEB
COPYRIGHT (C) 2011 SIPSTON
--
M0YSU
"G Daeb" <sipst...@my-deja.com> wrote in message
news:b9d14695-cb09-420b...@c29g2000yqd.googlegroups.com...
> Been talking about CBs at breaktimes (no pun intended)
> with a guy at work this last couple of weeks.
>
> Having asked about license application forms at the local
> Post Offices in town and about licensing regulations at a
> local electronics shop that stocks a small range of new CB
> equipment I got on-line and went to OfCom and got us copies
> of the 2006 information statement Of 364, titled "Citizens' Band
> (CB) radio spectrum use--information and operation" printed.
>
> I've just been reading through it this morning and some stuff
> seems not to quite add up, to me.
>
> Its hyphenation is inconsistent where the term "type-approval"
> is concerned and, as one of the instances has been hyphenated,
> I am assuming that all instances should be.
>
> But, yeah, it doesn't seem perhaps to be quite so well edited
> as it might be.
>
> And as, for now at least, we only have access to various
> incarnations of the UK 27MHz frequencies - standard UK40
> channel sets - rather than try to guess or infer what the reality
> is, I thought I'd ask here--seeing as this newsgroup does at
> least seem to be active on a basic level with some clearly genuine
> CB-ers posting from time-to-time.
>
> So okay.
>
> History time.
>
> The US started with a 40-channel AM system.
No, the US started with a 23 channel system, only expanded to 40 in the mid
to late 70's.
> In order to keep the radio unit working as long as possible,
> by not blowing components or overloading it to point of a
> general overheat, and get the best signal encoding, setting
> the SWR (standing wave ratio, the wave against which the
> signal is encoded regardless of encoding method) is critical
> to getting good performance.
Yes, the better the SWR the less chance of damage caused to the transmitter,
however, they can be repaired...
> Given different configurations of radio and antennae performed
> better at higher and lower frequencies, the general practice
> was to check SWR at channels 1 (the basement), 40 (the
> attic) and 20 (slap down the middle); often, setting SWR is
> a case of taking the average across the set.
>
> As such it's better to have 1:1.15 across the board than
> it is to have 1:1 in the basement and 1:2 in the attic.
>
> Also, given different configurations of equipment can perform
> better at the top or bottom of the band, the practice of using
> 19 as a calling channel in the US derived from the practice
> of people optimisimg SWR at channel 20.
Channel 19 was and still is the mobile channel. The only reason the SWR was
optimised at channel 20 was because it was midway through the band so if the
middle was spot on then the top and bottom of the band should also be well
in.
> And to avoid the calling channel getting stamped on by SWR-ers
> it was dropped down a notch.
Channel 14 was the general calling channel, same as what followed in the UK
but most remaining "breakers" tend to use the 19 now and 14 is rarely called
on. I don't think that channel 20 being used as the SWR'ing channel had
anything to do with that.
> Given how much effort those UK truckers who did international
> haulage put into lobbying for any kind of CB at all in the UK -
> and, with respect to HAMmers, it was the truckers not the
> Amateur stations who did, as Amateurs tended not to be able
> to see why on earth anyone who had not spent months building
> basic circuits under the auspices of their local technical college
> (NB,
> there aren't many of these in the Western Isles, where the local
> shop only gets a supply ship once a fortnight, nor in a great
> many other of the UK mainland's more rural areas), learning MORSE
> and taking series of tedious exams had any right to even think
> they should be able to operate WT equipment - 19 was left as a
> "truckers' channel" with 14 being the default "calling channel".
Yep... CB was for the common man, anything else you would chose the Amateur
route.
> Obviously so few people bother now that those days are long
> gone.
>
> But this does come up again, like now.
>
> So I've been looking at the frequencies for UK and EU (CEPT)
> which can be combined into 80 channels.
The PR27/97 stamp signifies the UK allocation of legal CB frequencies, "mid"
block as the standard european/worldwide 40 channels and the UK27/81 40
channel UK band all on FM of course.
> And taking the mathematical median point of the EU frequency band
> it would appear one should set one's SWR at channels 1, 40 and, er,
> 19.
>
> (26.965 + 27.405) / 2 = 27.185 (which is the allocated frequency
> for EU channel 19).
>
> Is that right?
It should be set to be at it's optimum wherever you use it most. I normally
SWR an antenna for a 27/97 radio on channel 1 UK. It works for me...
> Like, why?
Why not?
> Taking the range as a whole 26.965 to 27.99125 the statistical
> median is an inaccessible frequency (27.478125) which is not
> in either the UK or EU frequency bands.
>
> Now, we really are only talking about normal people running
> normal kit in a car, so the extent to which there's going to be
> a huge difference between having to trade 1:1.1 and 1:1.15 off
> is nil.
>
> If we can't get it below 1:1.2 anywhere then the kit will be going
> back to the shop/s, (and that's only assuming he buys any in the
> first place). And there's no question of running any more than 4W
> or anything like that--he wouldn't be happy about it.
>
> But still, assuming I end up helping SWR a 80 channel rig in,
> does anybody have any advice as to which channels it's best
> to concentrate on?
As said earlier it depends on what it's going to be used most on. I usually
set it to channel 1 UK.
> Otherwise, is the OfCom document OF364 right in its allocation
> table for EU frequencies in the first place?
Pass...
> I can see there are gaps in the band, presumably to make it a
> bit more difficult for anybody to build their own. But it also seems
> that the actual frequency for channel 23 is higher than for channels
> 24 and 25 (albeit lower than for channel 26).
Gaps in the band? If you refer to the "Alpha" channels they were, I believe
but may be proven wrong, set aside for model aircraft etc. so the CB
frequencies 'jumped' over them. Why channel 23 ran out of sync I do not
know, but remember, when CB came out in the US there were only 23 channels.
> Is this a typographical error? a quirk of the chipset which leads to
> it needing to be addressed this way in binary or HEX or whatever?
> Or a "security" control device to prevent people building their own
> using analogue tuners? Or a necessary workaround for how the
> frequencies operate at near the borders of various EU member
> states and other countries?
>
> One last thing: we've been watching CB prices on E-bay by way
> of his mobile phone. And no matter how low they start at, they
> almost always seem to end up higher for used kit, with you then
> having to pay carriage, than you can get brand-new kit with a
> full 12 month warranty on it from the few dealerships there still
> are on the high street.
Some of the older 27/81 kit seems quite collectable now, especially the big
cybernet sets like the Rotel RVC240, Harrier CBX, Binatone 5 Star etc. and
in many peoples opinion (mine too) have a better 'quality' feel about them
and are easier to repair than the newer breed of radios. Lots of modern day
CB's seem to be quite small with not so good sound quality however I must
say I do like the Maycom EM27's.
> I'm all for recycling kit, but really, I can only recommend people
> check the prices on the high street first--particularly given how
> much scope there is for the one you get off E-Bay to have been
> blown somehow or other by some berk you'll never meet...
Buyer beware, however If you pay via paypal you _will_ be able to claim your
money back if the item is not as described, unlike if you buy it 'on air' or
from a car boot/local breaker who will probably not refund you if it turns
out dud.
> I hope my questions make sense to someone, and that I've set
> them out in a logical order.
>
> Thanks in advance for any genuine, insightful and well-informed
> replies.
>
> G DAEB
No problem, I just hope I have been of some help.
73 Graham
Road_Hog
"M0YSU" <m0...@yahoo.comNOSPAM> wrote in message
news:VoKdnYxuZ7nAjL7T...@bt.com...
>
> Yep... CB was for the common man, anything else you would chose the
> Amateur route.
>
And anybody that didn't want to spend there whole time on air talking about
their tomato plants.
M0YSU
news:4e242f8c$0$352$7b0f...@reader.news.newnet.co.uk...
LOL, but when I lived in Brum there were plenty of oldies like that on CB
;o)
73 Graham
John H. Guillory
wrote:
>> Having asked about license application forms at the local
>> Post Offices in town and about licensing regulations at a
>> local electronics shop that stocks a small range of new CB
>> equipment I got on-line and went to OfCom and got us copies
>> of the 2006 information statement Of 364, titled "Citizens' Band
>> (CB) radio spectrum use--information and operation" printed.
>> As such it's better to have 1:1.15 across the board than
>> it is to have 1:1 in the basement and 1:2 in the attic.
>>
>> Also, given different configurations of equipment can perform
>> better at the top or bottom of the band, the practice of using
>> 19 as a calling channel in the US derived from the practice
>> of people optimisimg SWR at channel 20.
>
>Channel 19 was and still is the mobile channel. The only reason the SWR was
>optimised at channel 20 was because it was midway through the band so if the
>middle was spot on then the top and bottom of the band should also be well
>in.
the SWR on 40, then depending on which is higher, you either lower or
raise the size of the antenna. If you do it this way, your SWR will
be between that of 1 and 40 across the board. Get both as close
together as possible, preferably both being less than 1.3.... If not
possible, then assuming you only talk primarily on 1-2 frequencies,
pick the frequency you use the most and set the SWR on it, the rest
don't bother with...
>Channel 14 was the general calling channel, same as what followed in the UK
>but most remaining "breakers" tend to use the 19 now and 14 is rarely called
>on. I don't think that channel 20 being used as the SWR'ing channel had
>anything to do with that.
own channel, plants had their channels for checking in the truckers...
channel 6 is now used for Skip as is 36, 38, and I think 24. Channel
6 is usually busier than Channel 19, though.
>Yep... CB was for the common man, anything else you would chose the Amateur
>route.
80's because you need not have a license. Code was dropped in I
believe the 80's for Amateur, and being you can use more power, more
frequencies, etc. Why not... The test is not near as complicated, and
it seems to get easier every so often!
>The PR27/97 stamp signifies the UK allocation of legal CB frequencies, "mid"
>block as the standard european/worldwide 40 channels and the UK27/81 40
>channel UK band all on FM of course.
>> And taking the mathematical median point of the EU frequency band
>> it would appear one should set one's SWR at channels 1, 40 and, er,
>> 19.
>>
>> (26.965 + 27.405) / 2 = 27.185 (which is the allocated frequency
>> for EU channel 19).
>>
>> Is that right?
>
>It should be set to be at it's optimum wherever you use it most. I normally
>SWR an antenna for a 27/97 radio on channel 1 UK. It works for me...
>> Like, why?
>Why not?
Ratio is, or why it's so important.
>As said earlier it depends on what it's going to be used most on. I usually
>set it to channel 1 UK.
SWR's to where the lower channels where flat and the upper channels
where around 1.2:1
>> I can see there are gaps in the band, presumably to make it a
>> bit more difficult for anybody to build their own. But it also seems
>> that the actual frequency for channel 23 is higher than for channels
>> 24 and 25 (albeit lower than for channel 26).
>
>Gaps in the band? If you refer to the "Alpha" channels they were, I believe
>but may be proven wrong, set aside for model aircraft etc. so the CB
>frequencies 'jumped' over them. Why channel 23 ran out of sync I do not
>know, but remember, when CB came out in the US there were only 23 channels.
country...
>> One last thing: we've been watching CB prices on E-bay by way
>> of his mobile phone. And no matter how low they start at, they
>> almost always seem to end up higher for used kit, with you then
>> having to pay carriage, than you can get brand-new kit with a
>> full 12 month warranty on it from the few dealerships there still
>> are on the high street.
>
>Some of the older 27/81 kit seems quite collectable now, especially the big
>cybernet sets like the Rotel RVC240, Harrier CBX, Binatone 5 Star etc. and
>in many peoples opinion (mine too) have a better 'quality' feel about them
>and are easier to repair than the newer breed of radios. Lots of modern day
>CB's seem to be quite small with not so good sound quality however I must
>say I do like the Maycom EM27's.
Many folks in the US buy "import radios", which are often sold from
China, and are made either for european frequencies or a generic 10
meter / US CB / European CB radio, where you can change a jumper and
have it work on the band you want (or even work on all bands
simultaneously, which is illegal in the US). The problem is, when
converted for CB bands, it provides features not allowed, and the
radio is as you put it... Not Type Approved! But when your breaking
the law, you generally don't care about how many other laws you break.
Free bander's will transmit on whatever using whatever they have....
It allows them to transmit upto 175 watts on standard CB frequencies,
and in the US, it allows for USB, LSB, AM, or FM (even CW
technically!) But don't expect to get many folks to talk to you when
using modes not designed for that band. In fact, FM is illegal below
29.5mHz in the USA.
>Buyer beware, however If you pay via paypal you _will_ be able to claim your
>money back if the item is not as described, unlike if you buy it 'on air' or
>from a car boot/local breaker who will probably not refund you if it turns
>out dud.
before that advertised this great mechanic software, and various other
stuff that sounded cool... Got it in and it was a very cheap knock
off... Re-read the ad.... Lot's of fine details left out to imply it
was better than really was.... If it doesn't say something, don't
assume.... Eg. if it doesn't say the radio comes with power chord,
microphone, knobs, mounting bracket, etc. Don't assume it'll be
there... Heck, I'd be tempted to ask the guy if the fuse comes with
it... ;-)
>73 Graham
73 KF5QEO -- And yes I know this is an old post...
John H. Guillory
wrote:
>> And anybody that didn't want to spend there whole time on air talking
>> about their tomato plants.
>
>LOL, but when I lived in Brum there were plenty of oldies like that on CB
>;o)
hear 18 wheelers all the time talking about how they could see down
into those smaller cars, and could often tell if women had on panties,
weather they had on short skirts, etc. and weather they where wearing
a bra! I tried to tell her much is revealed when viewed from an
18-wheeler.... Then there was the summer beaches.... I liked to laugh
so hard when I heard a trucker say "Man, the women are getting more
homey looking each year!" ;-) I had to agree with him about the
local women... Funny thing is they just thought they was God's Gift to
men! Had they had a CB and listened.... They wouldn't be able to keep
quiet!
Ratticus
Hi Graham.
Its Jack, ex of Lockerbie, now of Australia. Remember a missing Midland
7001? :)
bolta...@boltar.world
John H. Guillory <jo...@netcommander.com> wrote:
>using modes not designed for that band. In fact, FM is illegal below
>29.5mHz in the USA.
it comes to broadcasting they usually seem to get things arse about face
in the states. NTSC anyone?
B2003