The DV4mini

I know the DV4mini is old news now... but I thought I should post about some of the exciting D-Star (and other digital amateur radio tech) developments of the last 10 months or so.

Number one on the list would have to be the DV4mini dongle... a small, low-powered 70cm digital "hot spot" dongle.  What makes the DV4mini different is that it supports multiple digital modes!

In addition to D-Star, the DV4mini can "talk" DMR (with support for both DMR+ and BrandMeister), Yaesu System Fusion, P25 and dPMR.

This amazing device originates from Germany and is a co-creation of DG1HT, DG8FAC and DJ0ABR.


When the DV4mini was first announced the demand outstripped supply.  It was originally available in very limited numbers from Helitron :-

Unlike today, sales were restricted to Germany (and a few other EU countries).

I was able to get an amateur friend in Germany to purchase one on my behalf and forward it on to Australia.

I've been using my DV4mini with two Windows programs.  The original DV4mini Control Panel;

and also with the DV4MF2 Control Panel.

Using the DV4mini with the Raspberry Pi has also been very popular.  Adding a small touch screen to the R-Pi makes for a very compact digital radio HotSpot!

So far the only other digital mode (apart from D-Star) that I have used with the DV4mini has been P25.

Amateur operation on DMR is VERY popular... I do plan on purchasing at least one DMR radio very soon.  There has been some amazing developments with DMR and amateur radio in the last year... I think it's time for me to jump on board!




The VK5REX Icom G2 gateway is down!

I didn't really want the first new post for many many months to be bad news... but it is!

On Tuesday March 8th 2016, after eight years of 24/7 uptime, the Dell Poweredge 1750 computer that has been running the VK5REX D-Star gateway software has died!

While the failure happened "all of a sudden", I believe the problem has been building for quite some time.  Living near the ocean has many benefits for humans, but salt ladened air is terrible for electronic devices!  The building that VK5REX lives in is air conditioned... dry air, nice and cool.   But inevitably, salty air works it's way in and through the forced air cooling system of the Dell server.   When it hits the warm insides of the computer, the moisture evaporates leaving the salt behind. 

This last week has been unseasonably humid for Port Lincoln. A lot of moist air from the tropical regions of Australia has been making things a little uncomfortable down here.  I believe this extra moisture combined with the salt residue has caused the server to fail. 
Upon opening it, I was greeted with a LOT of moisture on the internal boards, cooling fans and metalwork.  A quick "taste test" shows it to be very salty.

So what's next??   Well, a D-Star repeater with no gateway is a little boring! 

I'm committed to bringing an Icom G2 gateway back online as soon as I can.  The last backup was emailed to me from VK5REX two days before the failure.  I've never performed an Icom G2 re-installation after failure before... so it will be a learning process. :-) Other add-on software I used on VK5REX was not included with the weekly backup... g2_link, the ircddb client and ccs7 client will all need to be manually re-installed and configured.

I have secured a replacement rack mount server.  The party involved with donating the server will be acknowledged on the VK5REX website as things progress.  It was most heartening to see many amateur operators offer donations of suitable computer equipment in order for me to get VK5REX back online.

In the meaning I have a stop-gap measure in place.   I have set up a Debian computer running the excellent G4KLX open-source ircDDB Gateway software and have it connected to the existing Icom D-Star repeater controller and RF hardware.  At the moment it does not accept any incoming connections, nor does it have a dashboard page.  It's more to give local users the ability to establish outgoing connections to Dplus, Dextra and DCS reflectors.

Updates will be posted soon.



VK5REX C is operational!

Sorry for the lack of posts over the last few months. 

On the 29th January 2015, Tony VK5RF and Michael VK5ZEA drove to Whyalla (540 km round trip) to collect three duplexers from the QTH of Arne VK5NEX.   In the previous week, Matt VK5ZM had transported them from Paul VK5BX in Adelaide (390km).  Quite a journey!

One duplexer was destined for the VK5RAC 70cm FM repeater at Pillaworta Hill.  This was built from a flat-pack notch duplexer and a pair of bandpass cavities.  The notch duplexer was the one previously used at the VK5REX D-Star repeater.  This was to replace a HUGE six cavity duplexer that was too big to fit in the rack.  The new duplexer fits nicely in the 19" rack, sitting just above the 70cm repeater equipment.

The other two duplexers were for the VK5REX D-Star repeater and these were installed on the 31st January 2015.  A new 70cm duplexer to replace the temporary unit provided by Paul VK5BX.  This new duplexer uses my original 1MHz wide six-pole DCI filter, a notch cavity filter and a pair of pass cavities.  A circulator/isolator is also used on this duplexer.

The performance of this new duplexer also allowed me to permanently remove the ARR 70cm preamp from the receiver path.

The other duplexer has been a long time coming!  The 2m VK5REX C D-Star repeater finally has it's own duplexer and is now fully operational.  The home-brew 2m D-Star repeater has been operating with a hybrid two antenna setup for a while after it's installation, and for the last year or so has been off the air.  The repeaters VHF folded dipole has been used for the MarineTraffic AIS receiver

Eventually I'd like to relocate the VK5REX C antenna higher on the tower... but that will have to wait until the weather is a little more predictable.  For now I am more than happy just to have it on the air!

You can find more photos in the gallery!

Thanks to Paul VK5BX, Tony, VK5RF, Matt VK5ZM and Arne VK5NEX.




North West Digital Radio Thumb DV

A few months ago the guys at North West Digital Radio announced the development of the DV3000U or Thumb DV product.

The Thumb DV packs the same DV3000 AMBE vocoder chip found in the DV3000 Raspberry Pi/UDRx440 plug in board in a convenient USB "thumb drive" form factor.

I put my hand up for a Thumb DV and I received one from the first production run.


At the time of writing this blog post, the Thumb DV has software support via AMBEserver for Linux and AMBEserverWin for Windows based machines.  The G4KLX Dummy Repeater software can use the AMBEserver via UDP IP.

I believe direct connected USB support for the Thumb DV in the both the G4KLX Dummy Repeater and the Dutch*Star WinDV software isn't too far away.

At US$119.95 + shipping, the NWDR Thumb DV represents excellent value for money.  This product places the DVSI AMBE3000 chip in an easily deployable and convenient form factor. 

I hope the availability of the Thumb DV will prompt both hardware and software developers to create new and exciting products for amateur radio.  There is a LOT of D-Star hardware support for GMSK modems, but not a lot for other digital formats.

You can find the Thumb DV specification sheet here.




JARL D-Star Protocol Specification Ver.5.00

Today I noticed a new, updated JARL D-Star Protocol Specification document on Satoshi's web page.

It's been quite some time since the last update... Ver.4.3c was released in March 2004!

I have sent an email to JARL enquiring if an English version will be produced.  Hopefully the entire document will be translated, just scanning through and picking up on English words it seems there is a lot of interesting stuff in there.

I also sent an email to Satoshi, asking him what was new.  He replied that there is a new part defining the new data only D-Star mode where the entire 4800 bps D-Star stream is used for data (no interleaved voice/data).  This mode will make it's appearance in the soon-to-be-released 50th anniversary edition of the Icom ID-51A/E radio.

Satoshi has also confirmed that existing repeater infrastructure/gateways will be able to deal with this new data only mode.  

Seeing as the ID-31A/E, ID-5100 and IC-7100 radios have user upgradable firmware, I hope they will be able to support this new data only mode.