Thread: Sideband CB (27MHZ) Radios Making a Comeback - Cheap Long Distance Comms

Hi I have both UHF & 27 meg SSB, The UHF is clearer but useless around Melbourne, too many idiots who spoil it for everyone else. The 27 meg is now very quiet, often when I swith it on all I get is silence.

It still works well I have spoken to most Australian states including Tas. Once out near Alice Springs there was no mobile phone reception, no UHF but I was still able to use the 27 meg on ssb.

I wouldnt suggest it as a reliable means of communication as long distance is influenced by weather conditions.

I like your idea it would work well.

Andrew

I thought that SSB still transmits in 5 watt, but because it only uses part of the wave as carrier, as opposed to the full wave for basic AM, it had the effect of a higher wattage.

I'll have to dig out the books and check again.

And, Yes. A SSB network would be interesting.


EDIT.

From the Adelaide Hills, we used to speak with guys in the US quite often with our base unit, as well as other far flung places.

Originally Posted by d@rk51d3

I thought that SSB still transmits in 5 watt, but because it only uses part of the wave as carrier, as opposed to the full wave for basic AM, it had the effect of a higher wattage.

I'll have to dig out the books and check again.

And, Yes. A SSB network would be interesting.

From the ebay seller's website - relating to the Cobra:

40 AM and 80 SSB Channels - 40 AM, 40 Upper Side Band, 40 Lower Side Band 4 Watts AM, 12 Watts SSB - The maximum allowed by law. SWR Calibration - Allows calibration of antenna system for maximum performance. 9 Foot Mic Cord - For easy reach within any area of the vehicle. Front Microphone Connector - Allows convenient installation to be in dash or under dash. Tone Control - 3 position control allows fine tuning of audio levels. Adjustable Dynamike Boost - Dynamically boosts microphone for increased voice clarity. Tactile Controls - Allows you to actually feel where the dial is in it's rotation without taking your eyes off the road. PA Capability - Use CB radio as a Public Address System with PA speaker. Receive signals can also be monitored through PA. RF Gain - Adjusts receive gain in weak and strong signal areas. Switchable Noise Blank - For increased noise reduction.

Great to hear we have at least 3 of us for an AULRO network !

All we need to do is pick a club landing channel and make it ours... !

Back in the old days....
Many times I and my friends have spoken on sideband to someone on the west coast of America from a car on a 5ft helical (when the conditions were right).
I still have my old Pearce Simpson Super Cheetah.

Belt Pulley drives on tractors were a great thing back in the'40's. They allowed farmers more flexability and cost saving in the powering of pumps, saws and sundry other equipment. Technology improved and now the belt pulley is a thing of the past, replaced by the PTO. It's the same with 27 Mhz CB.
Like many others I had my CB radio back then, a Johnston Viking, PLL front end for zero drift it was a great piece of kit. You could even work out the 'binary' coding of the tuner and create your own out of band private channels. But like the Dodo it couldn't evolve due to it's inherrent limitations and became extinct. VAS 980 or was it 981? that was me.
The reason 27 Mhz CB became extinct was basically because it was unreliable (you could talk to your neighbour one day but not the next but you could talk to someone 100 miles away), complicated (tuning in SSB signals could be a nightmare), inefficient (AM is a huge waste of spectrum) and complex ( most users had no idea of the relationship between AM, USB and LSB which led to confusion, frustration and unreliable communications.
To use a 27 Mhz CB effectively you needed to have some theoretical knowledge of radio transmitters. When you transmit on AM you actually transmit three signals. The carrier frequency, the carrier frequency plus speech (USB and the carrier frequency minus speech (LSB. This is very wasteful of power and bandwidth as all the information is in either sideband. So if you can suppress the carrier and delete one sidband you can put all of your legally allowed power into one sideband and have a much better signal. This is why the power allowed on SSB is higher than AM. The actual radiated power (AM and SSB is the same. Unfortunately all it needs is one person nearby to use AM at the same carrier frequency as you and your mate on the other sideband and you're both gone.
UHF FM was a far better idea. Better use of spectrum allowing more channels, smaller aerials, better quality speech more flexability, CTCSS Selcall etc. But best of all reliability. You now had reliable comms. The bloke you spoke to yesterday you could speak to today and tomorrow as well. UHF is line of sight, and isn't bounced of the ionosphere (skip), to screw up not only your comms but also someone elses several hundred miles away.
As for "and thousands of truckers still use it", you've got to be kidding, for the reasons outlined above.
".............I will definitely be adding a 27 MHZ Cobra unit - for that extra safety in remote areas". Only if you're totally suicidal. It doesn't have the reliability, the range or someone listening at the other end. Don't even think about it.
.............."and ability to tap into the truckers network for long distance traffic updates". Pure fantasy.

"- in clear atmospheric conditions, ranges of 50-100 KM are common, and where the cloud conditions are right and create enough skip, you're reaching people all round the country - in a mobile, whip antenna set-up"

Theres no doubt a bit of fun can be had, the challenge of taking advantage of ionospheric conditions to talk long distance. If on the off chance there is someone to speak to at the other end. But for this sort of game you're going to need somethig better than a whip antenna, the most inefficient of all antennas. Work out 1/4 wave at 27 Mhz, and you'll need two of end to end, makes it a bit hard to point in the right direction.

Don't mean to rain on your parade Gav but 27 Mhz CB is not serious communications.

Deano

I take your point Deano.

Back in reminiscing mode: Back in those days, there was no internet, no fora to post on. ABC, Bill Collins' movies and a good long chat with the parents were the most obvious options for a Saturday night. Fiddling with a sideband CB was most interesting for a young lad which, for many of us here, probably led onto owning a Landrover.

Some of us do like to look back into and experience the past. Its a good way to see how far we've come.

ahhh yes, death of a good thing due to the lazieness of society to learn a skill set when something cheaper with half the abilities can do the job with less experience.

I know what kind of radio's Id rather have with me if I was stuck somewhere.

Originally Posted by Blknight.aus

I know what kind of radio's Id rather have with me if I was stuck somewhere.

yes, but if you were in the FFR they tend to be mounted in, whats the chances of getting stuck?