Diamond X200N Antenna

I installed a Diamond X200N on the roof and I have to say I am rather impressed by this antenna. The installation is the typical Diamond setup, you see one you see them all. It’s very simple to install.

The reason I chose this model over the others in the Diamond range (and all their clones) is that it looked like a good compromise between size and performance. The X50, slightly smaller at circa 170cm, was another candidate however I read in the specification that in VHF it’s a single 6/8 wave element; the X300, slightly bigger at 300cm, was a 2x 5/8 wave in VHF and had a similar performance to the X200, also a 2x 5/8. There is 0.5 dB performance difference on the paper and apart from the fact that I don’t believe this difference exists, half dB can hardly make much difference. The extra 5/8 UHF element must be the selling point of the X300 but all in all I thought that 4x 5/8 wave elements in UHF would be more than enough. So I picked the X200. The “N” suffix means it comes with an N type socket, so you need to terminate your cable with an N type plug. I am not sure this makes a huge difference in the real world, however there was no SO239 option available so I went for the N option.

As I was saying, this antenna feels very impressive. I installed at about 7 metres above ground level with clear view of the countryside between N and E. I then ran a quick sweep of both the 2m and 70cm to bands to check the signal of the local repeaters. I was shocked when I managed to trigger a repeater located about 85Km N from where I live – with probably less than 5W (5% power out of my IC-7100). Well beyond my initial expectations. Other rather distant repeaters, say between 50Km and 100Km, analogue and digital, can be accessed with the same power level, both in VHF and UHF.

Under the X200 there is a horizontal Delta Loop, connected to a 450 Ohm balanced line. This will most likely be the subject of my next post. I haven’t properly tested it yet as I need to create some space for a new shack and properly fix the balanced feedline so that it doesn’t couple with other metal objects. Stay tuned.

XRF400 retired as of 16 March 2016

Due to other commitments I have been unable to develop and maintain XRF400 since mid 2015. I kept the reflector coasting for almost a year however due to lack of use and community interest I came to the conclusion that it is time to move on: XRF400 is officially retired as of 16 March 2016.

From Russia with love

Summer means travel, and this year I will be in Russia until Fri 31 July. I packed my IC-7100 in the suitcase and I hope today I will be able to find a pole forĀ a temporary wire antenna on 10-15-20 metres (I’ll leave 40 and 80 for another day) to operate either from a fixed base or portable. All going well I should be able to operate as RA/M0ZZM and somehow advertise my presence on a DX cluster.

One thing I’d like to do is experiment with direct D-STAR contact in HF, this will have to be on 10 metres (I was thinking of the 29.4 MHz region) as it is the only band allowing the 6 KHz bandwidth required to operate. So if you are also looking forward to test D-STAR under propagation conditions, my QTH locator will be around KO82, which is approximately 400 Km south of Moscow or about 2000 Km distance from central and southern Europe.

If you wish to schedule a QSO, please add a comment to this post.

How to reconvert a Linux-formatted SD Card back to Windows

If you have been playing with a Raspberry Pi and the usual SD cards, chances are that you also found yourself unable to reconvert your SD card back to Windows for normal use. When you try to reformat the card in Windows, you will most likely get to a point where you have only one primary partition with all the rest of the space on the card free, but you are unable to expand the partition to cover the whole available space. You will have something like 50 to 100 MB space in your FAT32 partition and many GB space that can’t be utilised.

Well, your frustration is over. Here is how to proceed to repartition your card as you wish – in Windows. No extra tools or software is required. In the below explanation, when you see [square brackets] you don’t need to type the brackets, just the content.

Before you proceed, the usual disclaimer: I tried this on my system and it worked well, however you do this at your risk and peril and if anything happens to your computer or your card while following these instructions, I am not responsible for it.

STEP 1: insert the SD card in your reader so that the computer can recognise it, then open a command prompt and type [diskpart]. You will be taken to a window where the prompt says DISKPART> or something similar.

STEP 2: display the list of volumes by typing [list disk]. You will see a list of disks, probably something like Disk 0 and Disk 1, with the capacity in GB for each disk.

STEP 3: select the relevant volume. In my case, Disk 0 was the computer’s HDD, Disk 1 was the SD card. I recognised it because the capacity in GB matched that of the card and I had no other storage devices connected to the system other than my HDD, which I also could recognise the same way (by looking at the capacity in GB). If you are still not sure, try to run [diskpart] and [list disk] without the SD card in the slot, and then again with the card; you should notice the difference and be able to identify the correct volume. Back to business, to select the correct volume, assuming (once again, check carefully your system first when you try on your computer!) that the SD card is Disk 1, type [select disk 1].

STEP 4: clean the unit by typing [clean]. Make sure you selected the right disk when you type this, as this will clear all your partition table!

STEP 5: create a new partition by typing [create partition primary] and format it by typing [format fs=fat32 quick]. This will quick-format your partition as FAT32.

STEP 6: type [assign] and your card will immediately become ready to use.

Multiple RF modules under one D-STAR gateway

As part of my effort to help a friend to configure and setup a system comprising of two D-STAR RF modules under one gateway (all running G4KLX software), I created this schematic layout of the system, assuming two different scenarios.

In the first scenario all the elements of the system are located within an internal private network operating within a NAT environment. In the second case, the gateway and one RF module are inside the private network and then there is a second RF module remotely located. All IP addresses are just examples, you will need to adapt the settings to your circumstances but the principle is correct and will allow you to get your system working.

Here is the file, I hop it helps. Please remember to quote the source if you intend to redistribute.