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Frequently Asked Questions v3, Last Updated June 2015

Here you will hopefully find answers to questions we are often asked about GB7BS.

If you can't find an answer to your query then feel free to contact us and we will do our best to help.

Q1. I can't access the Repeater. / How do I access the GB7BS Repeater?

A. The DMR Repeater GB7BS is operational. You must have a compatible radio programmed to the correct frequencies. It is on Channel DVU13 (Tx 430.1625, Rx 439.1625).

You will also need to program in the correct Talk Group (9) and network Colour Code (3).

Q2. How do I know if I am accessing GB7BS correctly?

A. If your radio is correctly programmed when you press your PTT you should hear a confidence beep or brief tone and or a LED may be lit RED. The repeater itself does NOT send any tones or beeps to indicate an end of a persons over, your own radio can be programmed to do this.

If you hear a continuous tone when you press your PTT then either you are not in Range of the repeater or there is a problem with the set up of your radio.

Q3. Where is the GB7BS Repeater located?

A. It is co-sited with the analogue FM Repeater GB3BS at Lansdown, 13Km East of Bristol. IO81TK.

Q4. Can I use my D-Star radio with GB7BS?

A. No. D-Star is not compatible with DMR technology.

Q5. I hear people talking about station ID’s, Colour Codes and Talk Groups, what’s all this about?

A.  DMR radio has some features that are relatively new to the Amateur Radio world. As such a DMR radio has to be individually identified, so each radio is given an ID.

A PERSONAL ID is very important so that personal calls and text messages can be sent to your mobile or hand portable, it’s likes a mobile telephone number, it should be unique to you.

You can register for a DMR ID at the following site:-


Radio’ with duplicate ID’s can be blocked from the system so please obtain a proper ID.

A Colour Code is a number that needs to be programmed into your radio on a channel by channel basis. The number range is 0 to 15 (be aware some radio’s use 1 to 16). Most repeaters will be using a Colour Code of 1. If your code does not match that of the repeater you are trying to use, then you will not be able to hear anything from that repeater. A colour code is similar to CTCSS on analogue repeaters.

Talk Groups are, for simplicity, like “chat rooms” where users of a repeater can be divided into Groups of people. If you join a Group you will be able to hear and talk to people in that group and only that group. Again, this is another item that is programmed into your radio on a channel by channel basis.

As an example, there could be a Talk Group for people who just like to talk about a specific topic of Amateur Radio. Or a Talk Group that allows users to talk and link to other DMR Repeaters.

In most cases, for general local repeater operation this Talk Group will be set to the number 9.

Be aware that ID’s, Colour Codes and Talk Groups are all elements that need to be programmed into your DMR Radio. In most cases, if any one element is wrong then you will not be able to talk/use the repeater.

Check with each repeater Group as to what settings they use.

Q6. If I buy a DMR Radio for the new repeater can I use it on the analogue repeater?

A. Currently, if you purchase a DMR radio then there is some good and bad news with regard compatibility with analogue repeaters or simplex use.

The good news is that a DMR Radio will work on both TDMA (Time Division Multiple Access) and FM modes. So, for example, you could have channel 1 programmed up to work the analogue repeater GB3BS and channel 2 could be programmed to work the digital repeater GB7BS.

The bad news. As things are at the moment, there are no dual-band dual mode radios for both 2M and 70cms; however I am sure this will change in the long term.

Q7. Who is paying for this new Repeater and how will it be supported?

A. Currently the GB7BS Repeater is being completely funded by G4SDR & G7FBD; this is to get the repeater up and running as quick as possible and to purchase the actual repeater hardware at minimal cost.

The repeater hardware is the most expensive part of the project and current Repeater Group funds would be hard pushed to cover the cost while keeping GB3BS running with its own costs.

Once GB7BS is established and in service we will look to see how this “free loan” can be slowly repaid. We hope that new members, donations and support will allow this to happen.

Q8. I use the repeaters and would like to support the Repeater Group. How do I join or just make a donation to help with its upkeep?

A. If you wish to join our Repeater Group and help support its upkeep then please visit our main web site www.gb3bs.co.uk and select the Membership drop down menu. Here you will find a variety of ways to join or make donations.

Q9. Will GB7BS be linked to other repeaters and/or DMR-Marc?

A. The Repeater Group has been in talks with other repeaters (7AA, 7JB, 7SD & 7DR) who have similar aims. Our first aim is to get the repeaters up and running in their own right, as individual repeaters. Once this has been completed then the next stage will be to link these repeaters together so as to form a wide South West foot print of coverage.

When this has been done we will then see if there is a need, or a want, to link further a field or onto the DMR Marc Network.

Q10. When GB7BS is established will the analogue repeater GB3BS be closed down?

A. The simple answer is NO. There are no plans to close down GB3BS, providing of course Ofcom continue to grant NoV’s.

Q11. I have more questions, can you help me?

A. If you have any queries or further questions we will endeavour to help you. Please use our Contact Us page.

Q12. Can I use a normal Linear on my DMR Radio?

A. It is not advisable to use a Linear to boost your Tx power. There are several reasons for this. The main problem is that a DMR transmission is Pulsed Power, not continuous like FM. Your linear will most probably not be able to handle this type of transmission or possibly cause broad RF noise to other time slots or channels.

The other reason not to use a Linear is that during a DMR transmission your transceiver is also receiving in-between the transmit pulses. So even though you are transmitting your radio is still switching to receive although you are not aware of this going on. It is a normal function of DMR. So your Linear will not be able to switch between transmit and receive quickly enough, as such you will loose some functionality of DMR, especially accessing the repeater from cold and if Roaming is being used.

If you are using the linear only while operating Analogue (FM) channels then there should be no problems.

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