Programming old VHF walkie talkies.

[Seano]

Slightly obscure question this, but you never know...

 

I recently picked up a bargain batch of cheap second-hand VHF walkies. At least, it seems like a bargain. They're ICOM IC-F3S, old but mostly in excellent nick and most of their fairly ancient ni-cad batteries seem to hold a decent charge.

 

I have a copy of their cloning software (running on DOS!) and I've managed to get it talking to a serial port and communicating with the handsets, all good so far.

 

But here's the snag - I can't seem to get the CTCSS or DTCS to work. I still hear transmissions on any given frequency regardless how CTCSS/DTCS on either radio is set. I guess I must be missing something obvious, but not a clue what. Can anyone shed any light?

[Lamplighter]

Is the monitor button depessed, if so it will over-ride any tone or dcs requirement. It is a long time since I programmed one of these, but seem to recall that you need to define the default squelch type per channel as well as the actual tone or dcs. The only manual that I found on line is not reall much help.

Brian

[Seano]

Is the monitor button depessed..

 

I don't think so. I'm not hearing any noise on the receiver when the PTT on the transmitter is not pressed. It doesn't have a dedicated monitor button as such, besides the PTT and up/down buttons there are five more that all have user-defined functions. One little one (which I have set as the key lock), and four more labelled P0-P3. I currently have P0 assigned as monitor, and it seems to behave just as you'd expect.

 

I was wondering if I need to define the squelch type, or enable the CTCSS/DTCS in some way but can't seem to find any option for that.

(Though there are a fair few options in the menus, mostly involving DTMF tones, trunking and such that I really don't understand at all.)

 

On the main channel programming screen each channel has a column for "CTCSS/DTCS RX" and another for "CTCSS/DTCS TX" which defaults to the same setting. Clicking on that you get a list, with the default option "OFF", below that a list of CTCSS tone frequencies from 67 up to 254.1, and above it a "DTCS" option that prompts for a 3 digit + 'N' or 'I' code if you click on that.

 

Unless I'm missing something, the only other thing I can find anywhere that refers to CTCSS tones is a separate "Continuous Tone" screen that allows you to assign nine tones or DTCS codes the same way you do on the channel programming page, and then if you assign one of the P0-P3 buttons as "C. Tone CH Ent" you can use that on the handset with the up/down buttons to select one of those 9 codes on any given channel.

 

I've tried that too. It seems to work - when I press that button (I'm using P1) the up/down buttons select between "ctCH - MR" (what does "MR" stand for?) and "ctCH - 1" up to "ctCH - 9". But regardless how it's set on either radio the squelch still opens on the one when the other transmits.

 

I've found an operators manual and a programming manual online, but neither is much help. I guess you might have looked at the same one.

 

 

 

 

<Posts again 10 mins later:>

 

Is the monitor button depessed, if so it will over-ride any tone or dcs requirement.

 

No, hang on a minute, you're absolutely right. I was just failing to understand how the monitor button works!

 

Apparently the radio powers up with CTCSS disabled, and a little ")))" type symbol in one corner of the display. Pressing the monitor button briefly turns that symbol off and the CTCSS works.

Further brief presses do nothing, but pressing and holding it opens the squelch (so I hear the white noise hash of the universe) and turns that little symbol back on so the CTCSS is disabled again afterwards.

 

Phew. Knew I was missing something at least semi-obvious, and it was beginning to bug me. Thanks very much for the pointer. :)

 

 

 

 

<10 minutes more go by..>

 

Gah. Nope, hang on, still not getting it.

Prodding the monitor button briefly turns off the ")))" symbol and CTCSS works, but the PTT apparently turns it straight back on again. That can't be right can it? Surely you don't have to re-enable the CTCSS every time you speak?

 

 

 

<Bit longer...>

 

Ok, I see. Sort of.

You do need to define squelch type and button behaviour per channel. Under "SW Action" on the channel programming page, there are various options to do with "audible" versus "inaudible" mode that govern whether or not CTCSS is enabled, and how channel select, PTT and monitor buttons affect that. Cool. If I bang my head against the "help" text a bit more I'll probably understand it eventually. Thanks again.

[Lamplighter]

A lot of that generation Icom radios were " open program" in that you were able to define the actions of almost everything. It took a lot of effort to make a radio simple to use but allowed all sorts of clever things and sequences to be achieved. It meant that you could customise a radio to work on a wide range of systems, once you understood the programming requirements. I think that you are almost there.

Brian

[Seano]

I am pretty much there now ta, at least as far as I need to go for the v basic functions I'm after. :)

Next thing is to work out how many properly usable batteries I have, if any.

[paulears]

Can't promise but when I'm in the workshop later, I'll see if I can find a more modern bit of software - the older stuff was quite clunky. I had a load of Icoms in my old hire stock, but I think I kept the software somewhere. The CH-MR function Icom use to allow a frequency in the programmer to be transferred to a memory - as in Memory Recall - MR, there's often a reverse function too MR-to VFO.

[Seano]

Cool, it might be interesting to have a look at that, thanks.

 

The clunky old DOS software works perfectly though, so no biggie. I was (am) just struggling a bit with the many options these radios give me. And the 'help' text that assumes a fair bit of basic knowledge I don't have. ;)

 

It didn't help that the second hand radios I bought seem to have been part of a fairly fancy set up in the past, so some of the existing settings were perhaps a bit esoteric. I have now realised I would have been better off starting from scratch rather than reading in the existing settings and editing from there. But it was interesting to see, and I may yet spend time trying to figure out why they were set that way.

 

All I really needed was to re-tune to the proper frequencies to suit a cheap UK Simple licence and set up a few CTCSS tones* - I've reached the point where I can definitely manage that now.

 

* - Or DTCS codes. Actually, there's a question - does it really matter which?

[abbotsmike]

Cool, it might be interesting to have a look at that, thanks.

 

The clunky old DOS software works perfectly though, so no biggie. I was (am) just struggling a bit with the many options these radios give me. And the 'help' text that assumes a fair bit of basic knowledge I don't have. ;)

 

It didn't help that the second hand radios I bought seem to have been part of a fairly fancy set up in the past, so some of the existing settings were perhaps a bit esoteric. I have now realised I would have been better off starting from scratch rather than reading in the existing settings and editing from there. But it was interesting to see, and I may yet spend time trying to figure out why they were set that way.

 

All I really needed was to re-tune to the proper frequencies to suit a cheap UK Simple licence and set up a few CTCSS tones* - I've reached the point where I can definitely manage that now.

 

* - Or DTCS codes. Actually, there's a question - does it really matter which?

 

I made that mistake with some 2nd Hand motorolas. Programming them had no end of issues until I wiped clean and started fresh!!

 

CTCSS vs DCS

 

Not really any practical difference. I believe DCS can take slightly longer to decode in some radios, which means people have to be more disciplined with Push Then Talk, rather than "push the button as I start my sentence". DCS are probably a bit more secure/private because they are less widely used!

[DrV]

DCS are probably a bit more secure/private because they are less widely used!

Neither type of code provides any privacy or security. They are both ways of preventing the squelch from opening on transmissions you don't want to receive. If you have a radio which doesn't use them then you'll hear everything.

[paulears]

If you want privacy, then go digital. Starts at around 90 quid a radio, or basic (as in few controls) for around £60. Digital is probably enough security for most, although encryption is also an option . Audio quality slightly worse than analogue, but as long as signal strength stays ok, no hiss or phuts. Either works or doesn't, as in most things digital. Some of the analogue radios provide sim[ple scrambling, but easy to bypass if you have similar kit.

 

Any form of tone sequence ID takes a short time for the three or five tones to be passed, although you can have them at the beginning or end of each transmission - end is best if all you need is ID, but beginning is required for squelch lifting, and then short transmissions can get lost. DCS and 5 tone systems tend to be more suitable for large networks - CTCSS works well enough.