Some good links..

Our Friends over at GB7HM – Hope Mountain

DMR Users Forum   London DMR-MARC and C-Bridge

GB7MB (us)  Facebook Group                        

UK Digital Hams (professional digital voice modes only no dstar/Fusion)
All work, text and images © GB7MB

Dial-a-repeater !

Direct Dial – as it’s known, is available on GB7MB – but what is it ? well, it’s good news from the Guys who run the kindly run the British c-Bridge over at and good news for British DMR-MARC Repeater users in general.
Quite simply, it allows you to direct your call to a specific DMR repeater – rather than ‘lighting up’ all the other repeaters inbetween, As you know, we have two timeslots (channels) on a DMR repeater, and so, careful selection of talkgroups must be chosen in order to make best possible use of both repeater channels (slots) ..  leaving a slot on the repeater available to locals at all times, while at the same time providing non-local connections. Being able to chat to your friend on another DMR-MARC connected repeater (without tying up any other repeaters) is a sure win for DMR-MARC users in the UK.
The talkgroup times out after 5 minutes, so does not constantly relay unwanted traffic to your home repeater.

This ability is enabledand you can now add these new talkgroups to your codeplug now.
GB7MB is TG 915

For the full list of Talkgroups to program in, visit the DMR USERS Forum.

All work, text and images © GB7MB

Chinese CS700 hardware manufacturer..

cs700notI wondered where the original Chinese manufacturer of these CS700 sets was hiding.. so it appears that this is them (apparently)   here is their site..   How true it is, i can’t tell.
interesting though all the same… unless you know better – in which case, write in and let us know !

All work, text and images © GB7MB

GB7MB changes to new UK c-bridge


As the end of March draws nearer, so does the date for all UK DMR-MARC repeaters to switch over from the the German  SmartPTT server that we were all using, to a new British c-bridge by the Guys at 

GB7MB was swapped over to the UK c-bridge at 21:40 approx on 18 March 2015, and also talkgroup hang time was reduced back down to 1 second, as we dropped UK wide which was deprecated to slot 1 and Local TG 9 no longer needs to keep hold of slot 2 for main local usage. GB7MB users will likely have noticed no changes.

All work, text and images © GB7MB

The newbie’s guide to not sounding like a newbie.

So, your shiny new DMR radio has arrived. You’ve obtained the programming software and necessary programming lead, stuffed in a few channels and ‘hello world, here I come’. But how to wet your feet in DMR without sounding like the newbie that you are?

First, DMR operation does share some commonality with ‘normal’ FM repeater operation. However despite the availability of worldwide communication little similarity to HF operation exists.  Remember, one reason you have just spent some of your hard earned cash is to sample the ‘crystal clear’ audio quality of digital radio. It therefore makes little sense to repeatedly, or singly, call CQ. Leave that to the DX bands where it serves the purpose of enabling station discovery and tuning.

Second, think about how DMR works and what you are saying. You listen through a repeater but listen on a talk group.

Third, when you call say what talk group you are calling on. For example if I am scanning all the ‘channels’ on GB7MB and hear a station calling ‘G9ZZZ listening through’ by the time I have looked at the display of my belt mounted radio I have no idea what time slot/talk group G9ZZZ was calling on. better to say ‘G9ZZZ listening world wide’ or ‘G9ZZZ listening MB local’.

Fourth, treat the limited resources of the DMR-MARC network with respect. If you need to do testing, do it on the local non networked channel. Avoid long QSO’s on the world wide talk group, the suggested polite limit is 2 minutes. Move to a more local talk group if possible.

All work, text and images © GB7MB

The Hitchikers Guide to MotoTRBO CPS


To Quote Zaphod Beeblebrox in ” The Hitchikers Guide to The Galaxy  ”
(like i need to put a link to it’s Wikipedia entry)

” It’s the weird colour scheme that freaks me. Every time you try to operate one of these weird black controls,
which are labelled in black on a black background, a small black light lights up black to let you know you’ve done it “

Well, it’s probably not quite as cryptic as the spaceship controls mentioned above, and the MotoTRBO CPS does have a decent help system included with it too, but for some new to the digital voice modes, it can appear somewhat cryptic, and we do occasionally see a codeplug with incorrect settings in.

Adding a new basic FM or digital frequency is simple enough, (see other articles on this site) but we really need to ensure that we are all good neighbours on the repeater and network, and, because we are guests on the network, we must follow the rules and not cause any issues on the system, because they could remove a DMR repeater off the network if this was the case. MotoTRBO sets are not Amateur Radio sets and they’re full of features which most Amateurs may well be unfamiliar with, and incorrect settings here can be problematic or antisocial, so we really do need to check and maybe adjust some of these.

General settings: 
Obviously your DMR MARC ID goes in “Radio ID”  and untick the “Private Calls” box,  Private calls are expressly not allowed on the DMR-MARC Network and not over GB7MB either at any time.

Talk Group Call Hang time adjustments – are not too critical, but probably set it to 1000 or 2000.
sign in/sign out is not used,   Test mode – doesn’t really matter – ARTS is not used either, so you may as well disable the ARTS tones too, the rest are mostly personal preference.
As you can see here, the codeplug i loaded up for this example needs tweaking.

radio disable

One of the most often strange things, especially on DMR repeaters, is that there is no courtesy tone (link to a pdf)  and many find that can be quite unsettling, as there is no noise or squelch tail on MotoTRBO repeaters .. (we at GB7MB are working on it though)  However, your MotoTRBO radio knows this too and the radio can itself generate a ‘beep’ where the FM repeaters ‘k’ tone or pips would normally be, and this is called the ‘channel free indication tone‘ and it’s very handy to have it switched on.

Another one, where a quick tone sounds when you press the PTT button, is called the ‘Talk permit tone‘  and can be set to sound on FM, DMR, both or none. I have this set on none on my mobile, but on my portables, i often have it set to on – on DMR – the reason is that if you sit down with the HT on your belt, it’s all too easy to set the HT into TX accidentally on the side of the chair or whatever, and not know !

You can turn all or some, tones off in the radio’s menu, you dont need a PC hooked up.


Many of that settings are self explanatory,  but before you start looking for help in the CPS, ensure the Help pane is enabled in the View menu and select EXPERT view too. Volume Offset is the tone volume.. ARTS basically, just bleeps the set when a valid transmission is received, and it is not really used on Amateur radio much.

In the Menu
Here in Menu section the you can configure the radio’s menu items and more.

!!   IMPORTANT  !!!
The radio Enable and Disable and it’s associated decode options like remote monitor and Radio Check should all be unticked too, because, however unlikely it may be, you really don’t want to accidentally  STUN, DISABLE or KILL someone else’s (or your own) DMR rig or have your Mic remotely switched on or worse whilst tweaking or experimenting with codeplugs and radios… it has happened, with users monitoring non Amateur systems – and as Amateur radio is full of people experimenting with radios, the possibility of this happening through incorrect programming of DMR channels, or 5 tone and MDC1200 etc. should not be ruled out, so good luck getting ABC123 Taxi’s to un-stun or revive your radio.

You probably only want EDIT and Text messsage Alert ticked in “Contacts” – most are to do with private calls, which are not allowed on GB7MB (or any DMR-MARC repeater)
Scan – One of the great things about MotoTRBO sets is their flexible scanning options, scanlists, (even if they are only 16ch max) which are something i wish All Amateur radio sets should have, I’m sure some may do, but all ticking these scan options enables you to directly add and remove channels from the scanlist on the fly, and that’s done via the rig’s front panel. there are an almost unlimited number of scanlists you can make, and if you have the IMPRESS DTMF Mic  it’s even easier and is much more fun to play with.

Anyway – lets move further down the CPS menu now, and over into the
Channel configuration window
, because there are a few bits in there to check..

udp headerhere we are, in a channel wide pane, now, you won’t have an option board fitted, so this will already be unticked and the others greyed out as above, ‘allow Talk around” is basically TX on the repeater output and that’s not exactly reverse repeater or listen on input as Amateurs sometimes like to use, (so near, yet so far Motorola) so i guess this is personal preference, but generally it’s pretty pointless.

IP site connect is only available on DMR-repeater channels.  Channel Inhibit pretty much stops SCAN from reverting back to this channel, and there’s little point ticking that too.
Compressed UDP Data  header – another one that’s not going to blow the radio off the shack table if you click it, but for other manufacturer (legacy) DMR radios that don’t have this feature, you can untick it to enable a little wider compatibility..    Below ALL EMERGENCY SETTINGS should be OFF !  The MotoTRBO Emergency system is not implemented on DMR-MARC or any British Amateur DMR repeaters that i know of.

In the channel pane, you should set your Emergency System  to NONE and set your rigs  TOT  (Time Out Timer) to something sensible,   300 – 400 seconds is ok on GB7MB at present.  We do ask you to ENABLE TX INTERRUPT on all GB7MB channels, although other DMR repeaters may well not allow this. This enables stuck PTTs to be remotely de-keyed – thus keeping the repeater free from accidental squashed (on TX) mic PTT keys etc.

TX Interuptable frequencies  wants switching off on your DMR radio when using GB7MB at present, until further tests are made by the repeater keepers. Private Call Confirmed should be unticked, and disable data call confirmed too. Please also disable Enhanced Channel Access and CSBK data on GB7MB too please. The keepers are doing tests with these parameters, and so far there appears to be no real benefit, on the contrary, it seems to have a negative call setup time and may actually increase or chances of ‘doubling’

tx interrupt
Hopefully these articles will help demystify some of the less often discussed parameters in the MotoTRBO CPS, and this is intended for all users to check their settings and make sure they are not clogging up the repeater with unwanted data and background services, and with a little bit of luck, help to make life on GB7MB better for everyone, and safer and more fun.
These recommendations may not be applicable on ALL DMR-MARC repeaters, and they may indeed change on GB7MB over time.

All work, text and images © GB7MB

How to update your contact list (Motorola)

It seems there is a little bit of confusion surrounding callsigns not being displayed in the radio’s screen.. here’s a quick ‘how to’ that may help. As for callsigns on the various monitoring websites, don’t worry too much about that for now, because DMR-MARC is doing some big changes to the network, so please be patient.

First thing you should know is that your rig is doing the job of translating the DMR-ID of the person currently transmitting to you, into a callsign and name for your rig’s display. The information to do this is completely held in a database in the radio, and it’s a very simple job to update it.

As more users are coming onto DMR-MARC you may want to update the contact list regularly. The radio can store a maximum of 1000 contacts, so when there are more than 1000 DMR-MARC IDs in the UK – you will have to delete some,  at the time of writing this article there are 968 in the contact list generator that we are going to use.

Some of your radio’s 1000 contact list capacity are taken up by Talkgroup configurations, but for most of us, that’s less than about 10, so at present we can fit all 968 contacts, and all needed Talkgroups into the radio ok.

A Website called TRBO LINK will automatically make you a codeplug (don’t write it into your radio, there are no frequencies in) You simply tick the regions of the world you want adding into your contact list. Here I’m assuming you are in the UK and wish to have all the present contacts displayed .. so here goes.

Go to the Trbo Link contact list generator site here and select the contacts you are interested in, like i did below..
the coloured bar tells you how many contacts you have selected so far..

select contacts on site

then when you have done that, check the number of contacts you have selected –  if you do go over 1000 contacts, notice that it tells you it will truncate the list, also remember that you will still have to lose a few contacts if you get 1000 or more – because a few entries in your rigs database will be used for Talkgroup configuration.

Next: Select the type of rig you have, or the nearest type,  mine is the DM4600 – so i chose DM4601. and click the Generate button. save the file to your PC.

rig type
Okay,  so, the file it gave you is a codeplug, it will be named something random like 98649867509.ctb   although for clarity you might want to rename it something more meaningful like “2015 March 6 contact list only.ctb” that i am using in this example.

Next thing is to fire up the MotoTRBO CPS and read your radio – and save the codeplug you are using–  name this something meaningful too, because if you run into difficulties doing this, you may just want to go back to what you are using now instead, but i doubt you will have any problems, as long as you know how to drag ‘n’ drop in Windows, and select multiple files.
Now in your codeplug, navigate (in the left hand side Explorer type folder-view tree thingy) to the “Contacts”  blue folder, then again into the ‘DIGITAL‘ in there.. That’s where your contacts are stored. You might want to have the CPS sort these by name or type, if you do, right-click and select Sort and choose which option.  The secret here is to delete just the contact names and leave the Talkgroups, which sounds harder than it is, as the CPS already sorts the callsigns. Once you have selected the callsigns only, delete them.  You saved the codeplug before you started right ??

Now as you see,  i’m left with just Talkgroups in there. Yours should look something similar, Your Talkgroups are probably named something else. It doesn’t matter.

old contacts now gone

Now, In the CPS, keep your radio’s codeplug open and now click the ‘Open’ button and open the “2015 March 6 contact list only.ctb” (or whatever you named it when you downloaded it)   – the codeplug that the Contact Generator Website just sent you earlier.
open So now you have 2 codeplugs open in the CPS …  now go to “Window”  up there on the Menu bar and click ‘ TILE” then both codeplugs will be arranged one on top of the other, which makes for easy drag ‘n’ drop operations … Now in both windows, navigate (in the left hand side Explorer type folder-view tree thingy) to ” Contacts / Digital ”

drag new

Now you have your almost empty contact list in your radio’s CPS window, and the codeplug that the website sent you open in another window, both open at the ” Contacts / Digital ” folders.

All you have to do now is select all the full callsign list out of the downloaded codeplug, and drag and drop them onto the blue “Digital” folder of  your radio’s contact list.
– it may take a few seconds to either move,  drag or drop the new contacts into your rigs contact list.

If you’ve been successful you can close the downloaded “2015 March 6 contact list only.ctb” codeplug and you dont have to save it if it asks. but you now only have your codeplug open and you can check it for typo’s and other errors before you write it if you want.

If you want to add a new contact – like your mate’s callsign doesn’t come up on your display, it’s simple enough to add it.  You have the ID number that you want to display a callsign for. To add a contact, go to the ” Digital / Contacts ”  folder, right-click and select “ADD” Private call  – it will appear at the bottom of the digital contact list, likely named ” Call1 ” – right click it to rename it with the callsign you want displayed.  I called mine ‘Hax’ in this example as you see.. Of course, You type the callsign you are adding instead 🙂

make new private
rename it
(Apologies for the quality of the last couple of pics)

Now add the DMAR-MARC ID of the callsign you just added above, this one here 12345678,  is a silly example… dont use that, or don’t make one up,  a proper UK one will start with 235****   235 is the UK’s number.


I untick the ‘ Call receive tone ‘ (the CPS automatically switches this on when you manually add a new digital contact) and  set “Text Message Alert” to “Momentary” too.
Now – once you have checked all this, and it seems ok, it’s time to write it back to your radio. You will want to SAVE this codeplug too, as usual, i strongly suggest naming and dating the codeplug’s filename accordingly.

Have Fun..

All work, text and images © GB7MB

DM4600 audio out – the missing feature..


The DM4600 radios are very good indeed – they do a lot of things and perform well, but here’s one thing that bugs a lot of people … where is the audio out jack ?

Well, of  course, there isn’t one, sorry about that.  remember these are not designed for Amateur radio use, it’s PMR gear, and in the age old spirit of Amateur radio, we adapt these commercial sets to our own use, and adding an line out jack is a simple 10 minute job..  if you already have the parts.

I hope you have studied the great article  HERE by our very own Mot Orious here on MBARS,  about building a little audio preamp for use with these sets too – and you will have noticed the nice selection of pins on the back of the DM4000 and DM3xxx sets.

This little lead gives you fixed volume line-level audio out from the rig, whatever the front panel volume control is set at. That way we don’t have to drill holes in the set and put a 3.5mm socket in line with the speaker to silence the set when used on headphones !
I think this actually gives more control.. we can record or stream it around the house or into other audio equipment, provided they have line inputs. i dont know the actual output impedance from the accessory socket, but i imagine it’s reasonably high, and the fixed output it provides, easily drives some high impedance ear-buds form a mp3 player type device, with enough audio for comfortable listening without the need for one of those cheap in-line headphone amps off Ebay, or just making one with a op-amp.

First thing you need is the accessory connector… it’s pretty easily available, Motorola part number PMLN5072A and they are available on Ebay for £6 or £7 – (just paste that part number into the Ebay search box) or maybe a few pounds more, grab one off your local friendly Motorola dealer. Get the Ebay ones while you can is my suggestion.
Also get a 3.5mm in-line jack socket too… (or whatever plugs into your amp) we used 3.5mm jack because the friend i made the first one for wanted to use headphones, I ended up making one for myself too.


Here are the parts you need..  on the right are the three metal strips you see are the pins, and that small shiny rectangular thing above is the pin removal tool, should you need it, on the left you see the black plastic main shell,  and the 3.5mm socket lead around it.
Total cost around £8.

Prepare the 3.5mm cable – i used 2 of the 3 wires in the lead, as it’s a mono set, i only need one channel, so with a DMM check the tip and sleeve of the socket –  you can’t really get a meter probe into the socket, so as i bought a headphone extension cable, i snipped the unneeded plug end off and plugged that in the socket instead .. with the added bonus that the wire colours will be the same. I tinned the wires and fitted the pins..
tin wiresThen, after nipping the pins up with a pair of small long nose pliers, i heated the pins to reflow the solder that i applied when tinning the wires for added strength.  Now it’s time to decide where to put the pins in the shell,  so i referred to Mot Orious’s pinout HERE and it’s pin 14 and pin 16 we are interested in today..


That’s the two there we’re interested in – above, on Mot Orious’ diagram, Audio Ground and RX audio and below, the same pins as seen looking into the socket at the back of the DM4600

thats these two yellow arrows – this photo is just  looking straight into the back of the DM4600 connector – with the set the right way up. So, Pin 14 is the main RX Audio out pin (signal) and pin 16 is a handy ground right next door.  Note the way the pins are actually numbered here, it’s not the same as the anti-clockwise numbering you find on ICs.. oh deary me no. Instead, the numbering jumps ‘across’ each time, zig-zag like instead.

Pin 1 and the corner pins are numbered already on the socket, but tiny raised black numbers on black doesn’t exactly stand out too well, so lets be doubly sure here, and it doesn’t even hurt just to double check with a scope. which is what i did, this is what FM noise looked like out the back of my VHF DM4600 with the squelch open.

Right .. now we’re cooking, so make sure the signal doesn‘t change on our pin 14 when we turn the main rig’s volume down. Anyway,  you’re now ready to insert the 2 pins into the shell. Choose the pin that is connected to the ‘tip’ and insert that into pin 14 of the shell, making sure that the ‘barb’ on the pin faces upwards, as this will lock the pin into the shell, do the same for pin 16 too, and that the pins are locked into the shell ok, when you are done, leave a little bit of slack cable, and tightly apply the cable tie.

wires in shell

and now your Motorola audio-out lead is done.

finished 1Obviously it’s a very simple job, and is much the same as making the programming cable as Mot Orious detailed here, it’s probably going to be quite handy for some folks, and you can hook it to the car audio system if you like or what have you.


All work, text and images © GB7MB