G4CTP's Amateur Radio Hints and Tips

A challenge with the Retevis RT-3S, and other similar DMR rigs, is that the maximum number of contacts.csv entries is limited. In the case of the RT-3S, the maximum number of entries 120,000 - but the number of registered DMR IDs is now over double that quantity! Hence it is necessary to filter down the list in some way before loading it into the rig. The master file lives at  RadioID.net , although it isn't obvious where to find it. At the time of writing, the file can be found in Database / Data Dumps / user.csv.  RadioID.net offers downloads of filtered versions of the list, for subscribing users - currently $12.99/year. Alternatively it isn't terribly difficult to filter the list using Microsoft Excel. Really as an exercise in programming, I have written a Python program that can filter the list by country. The program and its instructions can be found here: https://github.com/V96GLF/DMR_Prune_Contacts  

So far in this series of articles we have: Built a codeplug for the Retevis RT3S, enabling it to operate on the Phoenix (DMR+) network via a local repeater. Built a Hotspot and added a new zone to the codeplug, so that the RT3S can access the Phoenix (DMR+) network using the Hotspot. I chose Phoenix initially, because that is the network that my nearest repeater uses. Whilst this gives worldwide coverage, it is not the only DMR network. Confusingly, there are quite a few networks out there - including Brandmeister, TGIF, FreeDMR and probably others. Each has its own layout of talkgroups and timeslots. Sometimes these are similar, and there are links between networks so that some talkgroups are accessible on more than one network, but each has its own quirks and so they are different and mainly incompatible. With a Hotspot, it is possible to join more than one DMR network simultaneously - up to four networks - using functionality known as DMR Master. In this blog we will look at buildin...

This is a quick addendum to Part 3 , which has been amended to include TG400. When operating on the Phoenix network using a hotspot, sooner or later you will have the frustrating experience of opening a user-activated talkgroup that is in use by a QSO... which you than can't manage to release so that you can listen to a different talkgroup. Unlike other networks, the Pi-Star dashboard does not have a "drop" option for Phoenix talkgroups. In fact, there are three ways to disconnect: 1. Wait 15 minutes without transmitting on that talkgroup. It will time out. You can monitor the timeout on the Phoenix F dashboard - it is the number in parentheses after the talkgroup number. 2. Reboot the Pi-Star! Drastic, but it works. 3. Make a group call to TG400 (yes, 400). I found this out from this useful post on the Pi-Star forum:  What is the correct method to drop a TG on Phoenix? - forum.pistar.uk So, to add TG400 to your codeplug: Create a Digital Contact with a Group Call to TG4...

1. What is a Hotspot? Part 1 and Part 2 described how to get a DMR rig onto the Phoenix network using a local repeater. This assumes, of course, that you are in range of a suitable repeater! What if you are not? Or if you are visiting another location without coverage? The solution is to build your own mini-repeater, known as a Hotspot. This blog assumes you have a DMR ID, and a working DMR rig. If not, please return to  Part 1 . A Hotspot is a low-power multi-mode digital repeater. It has an internet connection (wireless or wired) that connects it to the various amateur radio networks. And it has a small UHF transceiver that makes it accessible as a repeater from a local DMR handheld.  Hotspots typically support more than one mode and network - so they can be used to connect to Phoenix, Brandmeister, FreeDMR, TGIF, DSTAR and more. There are several commercial Hotspots available, and a few variations of software. Hotspots can be simplex or duplex, supporting one or two times...

What is a "codeplug"?  Confusingly, a codeplug is neither code, nor a plug! The term originates from a time when a physical plug was used to configure a radio's parameters. Nowadays it refers to a configuration file, which is typically prepared on an external PC and then uploaded to the radio. Overview This blog post continues from  Part 1 , and it assumes that you already have: A callsign A DMR ID A DMR rig - I will be using a Retevis RT3S for this example The programming software and cable for your rig. For the RT3S, the Windows software can be found here:  RT3S Software The example described below assumes that you are within reach of a DMR repeater on the Phoenix network, and that you know the details of that repeater (transmit and receive frequencies, color code). For now will configure the rig to access the DMR+ (Phoenix) network via a repeater. Subsequent posts will explain how to add analogue repeaters and simplex channels, hotspots, other networks, etc. The steps ...

To get started on DMR, you will need: 1. An amateur radio licence I'm assuming you already have this, but if not then you need to go here first:  Getting started - Radio Society of Great Britain - Main Site : Radio Society of Great Britain – Main Site (rsgb.org) 2. A DMR transceiver There are many of these available, and there are plenty of reviews on YouTube:  (7) dmr radio comparison - YouTube Chinese rigs are a good place to start, as they are less expensive than Japanese or American. I went with the Retevis RT3S (non-GPS version):  RETEVIS RT3S Dual Band DMR Radio GPS UHF&VHF Dual display Dual standby FPP Options for buying include: Amazon - https://amazon.co.uk/dp/B07DMDJN2N/ref=cm_sw_em_r_mt_dp_5DWR8BPC1QK7FSNSFK1R eBay -  rt3s | eBay Aliexpress direct from China -  rt3s - Buy rt3s with free shipping on AliExpress Note that Aliexpress now charges VAT at source, so there should be no additional duty to pay. Make sure that your purchase includes a progra...