Thread: UHF Vs CB

UHF is CB.

I think you mean what is the difference between UHF CB (477MHz FM) and HF CB (27MHz AM including SS

Read this: http://home.alphalink.com.au/~parkerp/cb.htm

I understand the UK CB frequencies are in the 27MHz and 934MHz bands so, no, an Australian UHF antenna will not work with either of them.

Ron

They use different frequencies - a CB is 27 MHz and a UHF (more common here for 4 Wheel drive use) is 476 - 477 MHz - so no - the old ariel won't work.

And a word of caution - I wouldn't buy any new radio that hasn't been on the market for at least a year, and make sure it wasn't assembled on Monday or Friday and that at least 2000 have already been produced.

"CB" (Citizens' Band) is an AM frequency, not largely used today.

UHF (ultra high frequency) sets are more popular now as they are generally clearer signal, although generally line-of-sight, whereas AM wavelengths are better in hilly country etc, so there is still a place for the old CBs.
The arials are different.

Should be UHF vs AM.

For a UHF to work properly you need the right cable of the right length and the right arial so unless your arial is for 477mhz UHF then the answer would be no.

Not stupid Q.

The difference is easily illustrated and similar to the difference between AM and FM on you car radio.

UHF CB uses FM to transmit your voice on a different frequency (477mhz) to HF CB radio which uses AM on 27mhz.
They can't talk to each other.
These differences also cause changes in the behaviour of the signal over distance, varying terrain etc.

I have both in my disco.

I dont know what freq. is used in the UK - but antennae work best when tuned to the correct operating frequency - if it's the same here as in the UK it'll work. If not damage may result

Stevo

Strangely enough when they 'legalised' CB in the uk - they moved the legal freq to FM -

Which really p***ed the chaps who had bought the old 'ilegal' 27 Mhz AM sets.

............

Quote

"The USA had for many years had a CB radio service, which by the late 1970's had 40 channels within a frequency allocation of 26.965MHz to 27.405Mhz , with AM and SSB modes permitted (Amplitude Modulation and Single SideBand).
It was equipment designed for this american service which found its way to UK shores to be thoroughly enjoyed, illicitly, by thousands of 'breakers' (CB'ers) between the mid-to-late 1970's and 1981. Media reports of late-1980 / early-1981 estimated, if memory serves me rightly, about 250,000 illegal CB operators in the UK at that time. Something had to be done...
The legal CB service introduced in 1981 - designated CB27/81 - permitted FM (Frequency Modulation) mode only, on 40 channels within frequency allocation 27.60125MHz to 27.99125MHz (unique to UK), leaving all of the equipment already in use rather 'out in the cold'.
In 1988 the UK finally had to provide a CB service within 26.965MHz to 27.405MHz , but still only FM, for compatibility with other E.E.C. (European Economic Community) nations - this was designated PR27GB. However, by this time, many original operators who still had old equipment (all-be-it in the attic) capable of FM mode on the 'Mid Shift' had probably either been sidelined by the original legal system's incompatibility, or drifted away from the new face of CB since its legal introduction.
It is possible that the introduction of a CB service in the UK, due mainly to the large-scale illicit use of CB type equipment, was the thin end of the wedge as regards opening up public access to the airwaves, as since that provision have come the following allocations, to mention but a few, in the sphere of personal radio telecommunications:- "

Originally Posted by mcrover

Should be UHF vs AM.

Not strictly correct.

477 MHz UHF CB uses frequency modulation (FM) whilst 27MHz CB uses amplitude modulation (AM) - of which SSB (Single Sideband) is a variation.

HF or UHF indicates the frequency band on which the transmission is made. The HF band is 3MHz-30MHz. HF CB sits inside that band. The UHF band is 300MHz-3GHz. (the band in between is VHF- Very High Frequency - 30MHz-300 MHz)

AM or FM indicates the method of carrying the speech on the rafio frequency signal.

Sorry to be pedantic but I was trained as a radio technician.

Ron