Ham Radio Blog by OZ1BXM

August 2010 - 2m brick amplifier
Meteor scatter operation is possible running the transceiver barefoot (50 W), but it helps to have more power. I found this 170 W brick amplifier from RF Concepts online. It was sold as second-hand equipment at the site brugtgrej.dk. This site is being visited by many Scandinavian ham radio enthusiasts for trading of used equipment.

170W PA from RF Concepts.

I am looking forward to write more on the subject Meteor Scatter next month. And I hope to have some QSOs to report!

July 2010 - Data interface
My Yaesu FT-847 transceiver needed a data interface because I plan to run WSJT and use the FSK441 mode for Meteor Scatter operation.

I found a clever data interface described by DJ4UF. The interface employs 3 audio cables, one RS-232 cable, and 5 components, which are mounted inside an alu-box. The interface is pictured below.

Yaesu FT-847 data interface.

The audio connection between the transceiver and the PC worked immediately. However, I had some problems getting the TX signal work properly. The FT-847 would not switch to TX. Troubleshooting was done and here is what I learned. The cabling between the interface box and the COM-port must be corrrect. It sounds obvious, but I had two wires connected wrong. The COM-port configuration must include "Hardware flow control" (screen dump). Finally, no "funny" drivers should be associated with the COM-port. I removed a port driver previously used by Ham Radio Deluxe. The interface now works flawlessly.

June 2010 - Preparing for Meteor Scatter
Recently, I have caught interest in a new propagation mode: Meteor Scatter (MS). The picture below (credit to jt6m.org) shows how it works: Station A points his beam antenna towards station B. A meteor trail (ionized trail) 100 km above the earth's surface reflects the signal, so the distant station can be worked. The range for meteor scatter is 500 km - 2200 km. The two bands often used for MS are 50 MHz and 144 MHz.

The radio signal is bounced off the meteor trail.

The equipment can be modest - just 50 W and a beam antenna is enough for making contacts. I am planning to use my current equipment (Yaesu FT-847 and 8-element yagi) and try some MS QSOs on the 2 meter band.

May 2010 - A strange place to nest
Two weeks ago, I entered the attic to check my coax-cables. The cables escape the house via slots in the brick wall. Much to my surprise, I discovered a wasp's nest hanging from one of the coax-cables (see photo). Obviously, the wasps had entered through the slot and transformed a piece of coax-cable into a nest site.

The nest was empty as I removed it. I don't want other wasps to find the old nest and start raising a new family!

The wasp's nest.

A wasp's nest is made from chewed wood fibres, mixed with saliva. The nest I found had a diameter of 12 cm (5 inches). Click the following link to view a picture of a wasp (Vespa vulgaris).

April 2010 - My experience with D-Star
I have used D-Star for some time now. It has been a different experience compared to analog FM on the 2m and 70cm bands.

There are few users. The number of registered D-Star users in Denmark right now is about 150. There can be silence on the channels for hours.

The D-Star audio quality is excellent with a clear voice reproduction. There is no trace of that machine-like voice, you can hear on some YouTube clips containing D-Star recordings.

The D-Star logo.

The communication range is large as all danish D-Star repeaters are interconnected via a reflector. You can speak to fellow hams hundreds of kilometers away. This linking creates a "national repeater". As more D-Star repeaters will be put into service, the "national repeater" will cover every corner of Denmark.

All repeaters have channnels covering the local area and by selecting a local channel you avoid having your QSO be overheard nationwide.

The satellite OUFTI-1 will use DV (Digital Voice) for up- and downlink. I am looking forward to use D-Star via a LEO satellite. OUFTI-1 is scheduled for launch in October 2010.

March 2010 - My first D-Star radio
The new D-Star protocol, which was developed by JARL (Japan Amateur Radio League), makes radio transmission and reception purely digital. This is a major change and will impact ham radio in the long term. I believe D-Star will upgrade and broaden the way hams communicate just like when we shifted from CW to phone.
Here are the major benefits of the D-Star protocol:

Enables connecting and linking via the Internet
Enables Digital Voice and low-speed data (DV)
Enables high-speed Digital Data (DD)

Icom IC-E92D portable D-Star radio.

To explore D-Star, I've bought a portable dual-band radio: Icom IC-E92D. It has D-Star built in from the factory and it can be used for FM and DV right away. It works on the 2 meter band and on 70 centimeters. I'll write more about my experience with D-Star next month.

February 2010 - Reaching worldwide with WSPR
The WSPR protocol is highly efficient when it comes to reaching distant places. The signal-to-noise ratio can be as low as -30dB or less at the receiving end.

On January 25th I let my transmitter broadcast WSPR both night and day on the 40 meter band with 5W output. The antenna was the loop skywire as described on this blog in December 09. I visited http://wsprnet.org at 10:00 AM to see how far my signal had reached. Much to my surprise, all continents were "worked". I write "worked" because WSPR spots do not count as QSOs. The map below shows the spots from that day.

All continents "worked" with WSPR on 40 meters.

The blue labels on the map indicate where my signal was received, or the labeled station was received by me, or both. If you click the label, an info box pops up and displays this information.

Even semi-rare DX stations can be found on 40 meters using WSPR. If you click on the image above or this link, you can read how ZK1AGG/P in Rarotonga, South Cook Islands received my 5 W signal later on the same day.

January 2010 - PC hardware upgrade
Four years have gone since I last upgraded my PC. Now it is time for new hardware. I found an upgrade kit in a webshop at 150 Euro. The kit consisted of a micro-ATX motherboard (Asus M2A74-AM SE), a dual-core processor (AMD Athlon II X2 240) with CPU cooler, and 2 Gbyte DDR2 RAM. I added a video card (Asus EAH4350 Silent) and a harddisk (640 Gbyte Samsung HD642JJ).

PC hardware ready for testing.

There was a problem during assembly of the PC: The new Samsung harddisk worked extremely slow. First, I tried to update the Asus BIOS to no avail. Then I googled the harddisk and found a firmware upgrade. Having installed that upgrade, everything worked normally for a while. Suddenly the throughput of the Samsung harddisk went down from 100 % to 2 %. Eventually, I changed the motherboard from Asus to the Gigabyte GA-MA770-UD3. The new motherboard solved the problem. I am now happy with my DIY PC.

December 2009 - Loop skywire antenna
I have considered which antenna would be best for DX and at the same time fit into my small garden. The loop skywire is the best kept secret in the amateur circle according to The Loop Skywire (QST November 1985). As 40-50 meters of wire can be accommodated on my suburban lot, it was an easy decision to give this antenna a try. My loop skywire antenna is 43 meters long and erected horizontally to the earth. It is supported in 4 corners and the feed-line is connected to one of them. The antenna resonates in the 40 meter band but is usable on the higher bands as well.

Loop skywire at OZ1BXM

My loop skywire is shown in the picture above. The wideband balun is a BL2 from Elecraft and the ATU is an SG-239 Smartuner from SGC. They are both enclosed in the same plastic box which is placed at the antenna feedpoint.

November 2009 - WSPR
I'll introduce WSPR this month. WSPR means Weak Signal Propagation Reporter. This software turns your ham radio station into a manned beacon station that can both receive and transmit.

Let us begin receiving. The software runs on a PC and uses the soundcard for decoding audio signals received by the radio. The audio is encoded in MEPT_JT which is a protocol developed by K1JT. The signal is FSK with bandwidth of only 6 Hz. Each transmission lasts 2 minutes and contains call, locator, and power output. The signal can be very weak (inaudible) and still be detected. The power level used by transmitting stations is typically between 1W and 5W.

WSPR receiving

The screen-dump above shows some WSPR stations detected at my QTH on the 40m band during a Friday evening. The (temporary) antenna was just 10 meters of wire tossed on the roof.

October 2009 - Morse Runner
Last month I introduced the free software application "Morse Runner" by VE3NEA, Alex. You can see the GUI below:

Morse Runner by VE3NEA

I have been using Morse Runner almost every day during the last month. I have found three advantages using this software:

1. My cw receiving ability has improved. My receiving speed (single calls) was 15 WPM when I started the training 4 weeks ago. Today, I can receive calls and reports at 21 WPM.

2. My cw sending speed has increased. This is mainly due to using the keyboard. Earlier, I used to send cw with a paddle and an electronic keyer. The keyboard, however, enables me to send much faster and without errors (except for typos). A nice side effect using a keyboard is the additional time you gain compared to manual keying. The secret is the use of macros. When I receive a call and type it in the "Call" field (for example SM5REA), I simply press a single key and the software sends SM5REA 599 012. Meanwhile, I can just relax. I find it easy to sip coffee in the middle of a QSO!

3. The sound picture provided by Morse Runner is highly realistic. You get a genuine 'radio feeling' when sitting in front of the computer wearing headphones.

September 2009 - Improving my CW skills
My CW skills need to be improved. I need to be more confident at typing calls at the keyboard, and thus perform better when contesting. I've found some nice and free software for this task: Morse Runner by VE3NEA. It runs under Windows or Linux. You can download it from Afreet Software, Inc.

Morse Runner is freeware.

Morse Runner can simulate a contest environment with QRM, QRN, QSB, flutter, and LIDs. It sends single calls or several calls at the same time (pile-up). I like this software. Thanks to Alex Shovkoplyas for developing it and making it available for everyone!

August 2009 - AO-51 celebrates the first Man on the Moon
Neil Armstrong was the first person to walk the surface of the Moon. He was followed by Buzz Aldrin shortly after, while Michael Collins had to stay in the orbiting Command Module. All this happened 40 years ago on the 20th of July 1969 (21th of July European Time). I was 11 years old that summer. All three men deserve honour and respect together with the huge number of people who made Apollo 11 a succes.

Buzz Aldrin on the Moon

AO-51 transmitted a special message during 20-21 July 2009 to celebrate the 40 year anniversary of the first Moon landing. You can hear my recording by clicking this link. There is some fading because I used a linear 70 cm yagi antenna, but the famous words by Armstrong can be heard between 00:54 and 01:04. A better audio quality is found in a recording made by KL7UW.

July 2009 - Keying the 23 cm transmitter
My 23 cm transmitter is the MKU 13 OTX up-converter from Kuhne Electronic. Keying is done by applying +12V to the converter, either to an external terminal or via the coax cable. As the converter is sitting near the antenna, I prefer keying via the coax. To support this function, I have acquired a bias tee (DCC-12) from SSB Electronic. When applying 12V to the phono socket, it sends 12 V up the antenna cable, but protects the transceiver from getting DC into the antenna connector.

Bias tee from SSB Electronic.

As my Yaesu FT-847 transceiver provides active low keying via the STAND-BY socket on the rear panel, I had to convert active low to active high. A few components were assembled on a PCB and put into a plastic box. You can click to view a picture of the whole assembly. The picture shows a mini-DIN connector for the transceiver socket, a 12 V power supply, and active high output for the bias tee. Mail me if you want the circuit diagram!

June 2009 - New 13 cm antenna

My old 13 cm antenna can be seen in the picture below. It is a homemade 5-turns helix antenna. The helix itself is made of copper wire. It has provided good service as a beginners antenna. Pointing the antenna towards the satellite is not critical, as the radiation pattern of the antenna is quite broad.

Homemade 5-turns helix antenna for 13 cm

My new 13 cm antenna is a 21-turns helix from Wimo (Helix13). You can see how small it is in the picture below, it's only 80 cm long. The helix is made of aluminium wire, which does not corrode like copper does.

21-turns helix antenna for 13 cm

May 2009 - Hustler 4BTV performance

You can't judge an antenna by listening or transmitting with it just a few days or evenings. You must use it for some time under different propagation conditions to make a fair evaluation.

The first thing I noticed about my 4BTV was the noise. On 20 meters, the noise level during the day was S3. The band was open, and many European stations were heard. Ground plane antennas have a general problem picking up noise more easily than other antenna types. And the vertical polarization of the ground plane is more noise-sensitive than antennas having horizontal polarization.

16 radials are attached to the Hustler 4BTV

April 2009 - Tuning the Hustler 4BTV

I've attached 16 radials to my Hustler 4BTV: 4 x 8'9" (2.67 m) for 10 metes; 4 x 11'9" (3.58 m) for 15 meters; 4 x 17'6" (5.33 m) for 20 meters, and 4 x 35' (10.67 m) for the 40 meter band.

Firstly I set the spacing between antenna elements to factory settings. This is indicated by "Initial" in the table below, where also the final measurements can be found.

A [mm]

B [mm]

C [mm]

D [cm]

Initial
50 + 55

50 + 50

45 + 45

155

Final
0 + 0

0 + 0

0 + 7

160

Hustler 4BTV element spacing

Dimensions A, B, C, and D can be seen in this figure, which is scanned from the Hustler 4BTV "Installation Instructions".

Secondly, my goal for the tuning process was to obtain SWR values less than 2 on any band. The final results are shown in the following tables. Had I desired to push SWR further down, I would have had to adjust the radials or to adjust the traps. Neither of these options were attractive this sunny Saturday afternoon, so I picked an antenna tuner from the closet and put it between the transceiver and the antenna.

MHz
28

28.2

28.5

29

29.7

SWR
1.0

1.0

1.0

1.4

1.8

SWR on 10 meters

SWR on 10 meters is just fine. A tuner is not needed on this band.

MHz
21

21.1

21.2

21.5

SWR
1.8

2.1

2.5

3.8

SWR on 15 meters

The SWR on 15 meters is poor. Acceptable SWR figures are only found in the CW portion of the band.

MHz
14

14.1

14.2

14.3

SWR
2.1

2.3

2.7

3.0

SWR on 20 meters

SWR on 20 meters is not satisfactory. A tuner should be used.

MHz
7

7.1

7.2

SWR
1.7

1.4

1.4

SWR on 40 meters

The SWR on 40 meters is OK - a tuner is not necessary here.

February - March 2009

The antenna project is currently put on hold.

January 2009 - More antenna preparations

The coax cable at the antenna end needs protection against rain and moisture. I used electrical tape and many brushstrokes of black Plastidip which is a multi-purpose rubber coating. I purchased a .429 liter can from a danish yachtshop.You can view the result in the picture below.

The coax cable is protected with Plastidip.

Another preparation task was repairing my SWR meter. I bought a used Daiwa CN620A cross needle meter some time ago. But it did not measure accurately as a 50 ohm dummyload connected to the antenna side showed SWR = 1.3. So I had to do some troubleshooting. It appeared that the 2 ceramic trimming capacitors within the sensor unit were broken due to age. The meter accuracy was restored after having replaced them.