A new DMR Repeater for West Devon....

Ham DMR repeater

  

 

If there's one thing missing in Devon and Cornwall, it's a Ham DMR repeater.

OK so it may not look quite like this but we have decided to go for a more subtle "camoflaged" approach.

 

 

 

r0 0 917 1181 w1200 h678 fmax

 .... is it G6BJJ's Bongo or NASA mission control? 

 

 

But rather like this ================>

 

 

 

 

Dragons head meet our new repeater keeper and guardian!

West Devon Raynet is joining with Cornwall Raynet to set up and provide Devon & Cornwalls first active dedicated amateur radio DMR repeater, to join the ever growing network of DMR repeaters around the UK and the world.

Full details of the project and the actual location are not being published in full yet, other than to say it will be on Dartmoor (somewhere) and is hoped to cover the West Devon and East Cornwall area.

Our biggest problem, apart from getting "Mint Sauce" the sheep to stand still whilst we all use the thing... is nailing & glueing all the bits together and weather proofing them to keep the Dartmoor summer blizzards and monsoons at bay.

Update 18/8/18:

GB7RD is now licenced and will be starting the first tests this next week. Initially it will be working in a "Stand-alone" mode for the tests.

Details for GB7RD are

TS1 (local) TG9 Colour Code 3, Rx 439.6875 Tx 430.6875

TS2 (link) TG's not yet activated whilst on initial tests but will again become Colour Code 3, Rx 439.6875 Tx 430.6875 

GB7RD has now joined and is part of the Devon & Cornwall Repeater Group.

Watch this space for more information.

The new DMR System...

gd 77  hytera md785 angle       MD9600     rt3

Radioddity GD-77                   Hytera MD785 Mobile                 Tyt md-9600                                 Retevis RT3/TYT MD380

Dual Band Handheld                                                                        Dual-band Mobile

DMR (Digital mobile Radio) is actually nothing new and has been around for some time. It is however new to the amateur radio world. Originally sold as a commercial system by Motorola under the brand MotoTRBO it is a highly effective system with a long pedigree and good track record not just for voice but also data.

Interest in all things digital in the radio world has been spurred on by the interest and growth of Icom's D-Star and Yaesu's C4FM Fusion systems. However for many the extremely high cost, (£400+ for a handheld, £500+ for a mobile) even when imported direct, cannot be justified. This is where the DMR sets come into their own for around 1/3 of the price. 

However they do work in rather different ways to the other main amateur radio systems, and this is where some confusion can set in... like anything new it can be a steep learning curve until you get the hang of it. Icom & Yaesu's systems are mainly a case of programming in your amateur callsign and the mode FM or a digital one (Auto C4FM, Narrow Digital [for voice and data], Wide digital [for voice only], D-Star etc. You also have the ability to input a frequency either in memory or to use a direct entry VFO.   DMR is different - it has no VFO, all information for each frequency/mode must be entered into a channel memory - then cross-linked with a common setup Zone. Each callsign must have a Radio ID which must be obtained from a central international registry. Like D-Star & Fusion, you can direct your call through a repeater network that is linked around the world to a specific location, or call set to set. The way this is done however is different with DMR in that it must be contained within the memory for each frequency, repeater or link. Again like other digital systems, voice transmissions are broken up into data packets of a fixed time duration and interleaved with header information to route the call to the appropriate destination. With DMR however, this is done by using TDMA.

Time-division multiple access (TDMA) is a channel access method for shared-medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots.[DMR uses 2 slots] The users transmit in rapid succession, one after the other, each using its own time slot. This allows multiple stations to share the same frequency channel while using only a part of the channel capacity. C4FM uses FDMA [Frequency-Division Multiple access]. see below. Each have their own advantages and drawbacks.

fdma v tdma

So which is best?

Thats a bit like asking which is better red wine or white wine. The answer is simply, its up to you.

Some people prefer red wine, some prefer white, some don't like either. In the case of Digital Radio a lot will depend on the depth of your pocket, the tolerance of your other half, your personal preference or what others are doing in your area. But for many it may well come down to cost. Can you justify spending ~£1000 for a mobile and handheld from the big 3 manufacturers (I, K & Y) or £300 - £400 for a DMR setup? (remember the days of VHS vs Betamax? Betamax was probably the better system but could not compete with the lower prices of VHS) 

see all about a new DMR repeater in Devon

Fitting the St1100 Police Switch Pod

Honda part  number: 35150-MZ9-900

Switch & Circuit Function Circuit Wire Colors Use
Connector Block 1 – (new block)
Switch cct 1 Locking 1 Light Green Amber Strobes
Switch cct 1 Locking 1 White Amber Strobes
Switch cct 2 Locking 2 Blue Amber & Red Strobes
Switch cct 2 Locking 2 Green/Yellow Amber & Red Strobes
Switch cct 3 Momentary 3 Green Not used
Switch cct 3 Momentary 3 Orange/Black Not used
Rocker switch 4 Locking 4 Orange Locking PTT
Rocker switch 4 Locking 4 Black/Blue Locking PTT
Push Switch 5 Locking 5 Pink/Black Radio Power on/off via relay
Push Switch 5 Locking 5 Red/Yellow Radio Power on/off via relay
Connector Block 2 - (same as original)
Engine Stop cct 6 Variable 6 Sep. Plug
Headlight Hi/lo 7 & 8 Adjustable

7-8

Sep. Plug
Engine Start Push 9 Separate plug

 

st1100 pol podFitting the new switch pod on the ST1100 is straightforward.

The Police Switch pod comes with 2 connector blocks (Red & Green). The smaller (Red) is the same as the original connector for the standard unit and plugs straight in. This is for the Engine start, kill switch and headlight hi/lo switch.

The extra block (green) is the connector for the P Spec ST1100, this needs to be adapted for a standard Pan.

The new pod has 10 wires (9 in a bundle into the new block, plus 1 free) and the colours are as shown. Unless you have the correct 10 way block already on your ST1100, it is easiest to cut the wires out of the block as close to the block as possible.

 

pol pod conThe maximum current rating for each of these cables is 5 amps. If you intend to connect anything which draws close to or more than 5 amps you will need to go via a standard relay.

I used a 7 core cable to run from the front to the rear pannier which housed all the extra battery and strobe gear, plus a 2 core PTT line to locking and momentary PTT switches in parallel. You could combine this and use a 9 core cable, but getting a cable rated at 5 amps is not easy and costs a small fortune. Also the cable diameter gets rather large.

 

pol pod wire

To Fit the Pod:

Note you will need new fitting bolts to hold the unit as the old ones will be too short.

  1. Remove the brake lever to give easier access.
  2. Loosen the brake master cylinder/fluid reservoir and slide it as far inboard as possible. The new pod is ~ 5 – 8mm wider than the original.
  3. Remove the retaining bolts and remove the old switch unit. Careful to not dislodge the throttle cables.
  4. Remove the old engine/headlight connector (Red?) making sure not to damage the sockets.
  5. Plug in the new engine/headlight connector (Red?) making sure not to damage the sockets. Wrap in waterproof/self amalg tape.
  6. Loosely fit the new switch pod onto the handle bar taking care not to trap the throttle cables or engine control wires.
  7. Adjust the position to allow correct operation of the throttle. Bolt down unit, again making sure free movement of throttle.
  8. Slide the brake unit back against the new switch pod and tighten locking nuts.
  9. Refit brake lever.
  10. Check for full and free movement.

Wiring the new Switch Pod:

You will need a 12v auto relay for the radio plus further relays for any kit drawing more than 5 amps.

  1. Run the 7 core cable to the rear o/s pannier.
  2. Run PTT cable to Radio as normal
  3. Identify each of the 10 wires from the new switch pod and arrange them in pairs.
  4. Connect pair 1 (light green) to amber strobe controller + and (white) to battery +
  5. Connect pair 2 (blue) to red strobe controller + and (green/orange) to battery +
  6. Isolate pair 3 (dark green & orange/black)
  7. Connect pair 4 (orange & Blue/black) to PTT line in parallel to push PTT switch on left handle bar and to Radio.
  8. Connect pair 5 (red/yellow) to 12v relay coil input (pin 86), connect (pink/black) to battery +, connect relay output (pin 85) to earth.
  9. Connect relay power input (pin 30) to battery.
  10. Connect relay power output (pin 87) (n/o) to radio.

 4p relay    5p relay

4 Pin 12v Relay Pin 30 is 12v live, 85 & 85 Relay coil, 87 ground.

5 Pin 12v Relay has an extra contact 87a. This pin is normally closed (& live) when the coil is un-powered.

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sunset on Tarka140516 sm nightwalk logo 200w     

North Devon Night Walk

TarkaHow about this for a bit of fun....

Each year the hard working team at the North Devon Hospice, hold a charity night walk for ladies only, between Barnstaple and Bideford, Starting at either end. Each year thousands of determined and boisterous ladies gather to take part, oure role is to make sure the event goes off smoothly, keeping the organisers updated on locations and numbers, plus anything untoward.

 

1583541  frem bridge2016 sm  Thro Bideford150516 sm 20150516 192237 sm NDNW1

This years Ladies only Nightwalk is overnight .19-20 May 2018 - good luck to all those involved.

 TaviGF  goose2001 AL  

 At the annual Tavistock Goose Fair which is held on the second Wednesday in October each year, we act as the link for the Police, South West Ambulance, St John Ambulance, Tavistock Town Council, West Devon Borough Council,   the Bus services and the Park & Ride Scheme.... as well as a general information and lost property, children and granny point!!!!

 DSC00139  Goose fair0004 20111012  1545080 10152561671423381 1762144194127945382 n

Here the "ISU", "battle-beast" or "Thunderbird 5" as it is variously known, is setup and running in the centre of Tavistock beside the Ambulance and First Aid points.          

Each year, we run from around 05:00 to 01:00!!!

j0095685...quick more coffee!!! 

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