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CTCSS Tones

In recent years, more and more repeaters have appeared that require CTCSS tones, or codes, to access them, and some of the older repeaters have been modified in this way too. In fact CTCSS became mandatory in 2004 for new repeaters. This has both benefits and disadvantages for both sides, so much so that they seem to balance each other out. By "both sides" we mean the traditional radio amateur, as opposed to those who want to introduce new technology - however an anomaly is that repeaters are required to identify themselves with the archaic Morse Code that dates back to the early 1800's. However, some repeater keepers seem to have had the temerity to use a speech synthesiser with an extremely offensive American accent!

A CTCSS tone is a Continuous Tone-Coded Squelch System, something brought over to the hobby from PMR. Basically what happens is a sub audible tone is superimposed on your transmission and the repeater recognises this and opens or re-transmits your signal without the need of the 1750kHz tone. In practice, you just key the mike and the repeater works without any further action from you. Some repeaters are yet to be modified, and some still accept both, but it will all be CTCSS soon, so we need to move on.

The old system meant that you could "whistle up" the repeater without a tone burst, but also spurious transmissions would activate it as well. CTCSS does away with that, ensuring that only the correct radio amateur signals are repeated. That is the supposedly good side of this, but it means that the majority of radios out there are obsolete, as they don't have a CTCSS tone facility. No problem, we are technical people, buy an add-on board and away we go! NO, if only it were so simple.

There are a whole set of tones, see the table below, and every repeater needs to accurately receive the correct one to work, before 1750kHz was universal, but now it is infinitely more complex. What would have been sensible would be to have adopted the same CTCSS tone for all repeaters in a specific area so you could buy a cheap tone board and easily fit it, but no, they all need vastly different tones and trying to use an add-on tone board is impractical.

The upshot is, we feel, a great contributory factor to the demise of 2 metres, the main conduit of conversation, the local repeater, has been made unavailable to the vast majority who can not justify the expense of a new radio with the CTCSS feature.

CTCSS was introduced to allow several commercial radio users to share the same frequency without overhearing the other users conversations, you could have 2, 3, or 4 companies sharing the same frequency but each using their own CTCSS tone, so the squelch would only open for calls intended for them. You can see the advantage of this in a densely populated area such as The City Of London. On paper, this looked like a good idea for ham radio, but in practice it has been disastrous, as even if the repeater is open, without the tone superimposed on your transmission, it simply will not work.

So CTCSS has to be used, luckily radios are remarkably cheap these days, with dual band handies 4 or 1Watt out costing under 30 new, and these incorporate the vital CTCSS tones. Mobiles also have had a dramatic price drop, even Yaesu are down to sub 140 for a full featured 2 Mtr with 50W out costs around 150 or less, if you can find a dealer these days.
 

Here is an example of a Baofeng UV-5R, this does everything and comes at various prices, the best we found was just under 30.00 including postage and VAT,

4 Watts out high, 1 Watt low, CTCSS tones, VOX, LiIon battery with mains recharger.

This is our current project for a repeater improver. With the addition of minor circuitry, it can be modified to randomly access a CTCSS repeater on 2 metres or 70 Cms, play a recorded "message", and close down again.

Test show it will last well over a week with 20 second transmissions every 30 minutes, we are experimenting with a light sensitive diode to switch it off at night, when it would suffer the highest danger of being found by direction finding.

Deployed outside, near the target repeater, it can be easily concealed, and collected every week or so for recharging. Make sure you use different locations.

Members in London used the top of a bookcase in the local library every weekend!

 

How To Get Round It

Basically, you can't, unless your interest is only one local repeater, then any radio can be modified with a tone generator board. These are easily found on eBay or with an Internet search, and fully programmable ones are out there for as little as US$16.00.

They need to be set for the CTCSS tone of your target repeater by means of jumpers or DIP switches, and seem to work across the mike input although there are more technical ways to inject the tone.

Programming Modern Radios

With the advancement of technology, gone are the days of simple radios with buttons that did what they said, now we have several levels of drop down menus to negotiate to do something as simple as saving a frequency in a memory.

With CTCSS tones you have to tune into a repeater in VFO mode, add the correct tone and check you can get access. All this information has to be saved into a memory for easy recall, if you memory save the frequency without the tone, when you recall the memory, nothing will happen.

It is a laborious task, and extremely annoying, I suggest you write down the key sequence, as by the time you have found step 3 in the radio handbook, step 1 and 2 will have reset. It is not too difficult, and after a few attempts you will easily remember the sequence. A slight hindrance is on Yaesu where not only do you need a complex system of key presses, some have to be pressed for half a second, some momentarily, and some for a second or more. This sounds worse that it actually is, as you will get the sequence right after a few attempts, rather than throw the radio through the nearest window, have a cup of tea, and try again. Better still, relax in the knowledge that there are complete and utter morons out there that have managed to do it - so you certainly can!

We are not sure if this applies to all modern radios, but all we have come across, including sub 30 handies, can be programmed by computer from a radio to USB lead.

FREE software is available HERE for most radios, you only need to find the right lead then just type in the details you want in your memories, and transfer it to the radio. Remember to keep a copy for upgrading etc.

We are not sure if this is progress, as it is hard to think how some of the dip sticks with amateur radio licenses even manage to switch the set on, let alone program it!

Modifying & Adapting for CTCSS

A quick search of the Internet will reveal many CTCSS devices, kits, and circuits for a tone encoder board. We have one of these, and can say it is well made, easy to use and very cheap to buy. Currently US$28.99 each, and ours took under 2 weeks to arrive, without any duty or VAT etc.

The tone can be sent easily by DIP switch, it runs an anything from 5-28 volts.

It's just the job for single repeater operation, although with a little ingenuity it can be made to switch tones, but maybe too much hassle.

All the info, circuitry, and information for interfacing with many different radios can be found here:

                 SS-64

If you want to support UK companies, there is the option of the CTCSS 47 Kit.

You will need to have a fine tipped soldering iron for this and a little skill, but @ 14.00 it is a bargain.

Programming via links, full documentation and details HERE.

CTCSS Tone Code Listing

Tone Number Frequency (Hz) Tone Number Frequency (Hz)
1 (Tone A) 67.0 20 131.8
2 (Tone B) 71.9 21 136.5
3 74.4 22 141.3
4 (Tone C) 77.0 23 146.2
5 79.7 24 151.4
6 (Tone D) 82.5 25 156.7
7 85.4 26 162.2
8 (Tone E) 88.5 27 167.9
9 91.5 28 173.8
10 (Tone F) 94.8 29 179.9
11 97.4 30 186.2
12 100.0 31 192.8
13 (Tone G) 103.5 32 203.5
14 107.2 33 210.7
15 (Tone H) 110.9 34 218.1
16 114.8 35 225.7
17 (Tone J) 118.8 36 233.6
18 123.0 37 241.8
19 127.3 38 250.3

The tones in white with a letter suffix are supposed to be the only tones in use on UK repeaters, and the letter code is given after the Morse ID when the repeater times out. If you can't read Morse, use a free application on an iPhone or Android device.

Now, as you can see, this is a lot more complex than a single 1750kHz tone to access all the repeaters! It may have seemed like a good idea, but in practice it has been a complete failure and forced countless people off the air, and resulted in the current situation where most repeaters lie dormant all day.

Even if you are not in agreement with LPWS policy towards repeaters, can we urge you to buy the SS-64 tone board, or similar, and ensure the repeaters actually get used. It will be a sad day when they all disappear, and we have nowhere to "play"!

 
 
      "Wicked" Willy Bodwen ex Sgt. 3116 (forced to retire & not a laughing policeman!)

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