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...

It took me a long time to figure out how to enter and leave VFO mode on the RT3S, because the menu options seem to keep changing! Entering VFO mode is shown in an official video here: https://youtu.be/-q6lOVjAwJs In summary, and starting from "CH Mode", the steps are: Menu > Utilities > Radio Settings > Mode > MR Mode The display should now show frequencies in MHz rather than the channel name. The functionality is unchanged, and you can still access your programmed channels as normal. Notice the small channel number indicator to the right. To get to VFO mode, long press the red key. The indicator to the right changes into a "V". Frequencies can now be entered directly from the keyboard, terminated by the green key. Rotating the channel selector knob now changes the frequencies in channel steps. I haven't worked out how it decides whether to use 12.5 kHz or 25 kHz steps. On mine, the A VFO steps in 25 kHz, and the B VFO steps in 12.5 kHz. Perhaps that...

This is a pretty simple one, but I thought it might be useful to create a Zone containing the 2m and 70cm simplex channels. There aren't enough slots to include the "in between" 12.5 kHz channels, so I have only added the more commonly used 25 kHz channels on both bands. First, create the Channels: I have named them using both the old and the new channel name conventions, i.e.: V40 (S20) - 145.500 MHz V42 (S21) - 145.525 MHz, etc. U280 (SU20) - 433.500 MHz U282 (SU21) - 433.525 MHz, etc. If you need it, a list of channels can be found here:  Simplex_Channel_Frequency.pdf (joomla.com) Note that for the 2m band, the Bandwidth should be set to 12.5 kHz, and for 70cm it should be 25 kHz. Apart from that, the settings are similar: Next, I created a Zone called "FM Simplex", and added each of the channels to it. For convenience, I put 2m channels in bank A, and 70cm channels in bank B. In each case, I put the calling channel in slot 1: Finally, I created a scan group ...

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...