Using AMSAT-UK crossed dipole with AO-73

[wd9ewk]

Hi!

A little while back, I ordered the crossed dipole sold on the AMSAT-UK web site. It arrived just before I left for Dayton, so I have not had a chance to work with it until this weekend - a holiday weekend here in the States. After mounting the antenna on a tripod and mast I had for another antenna, I was able to try it out in my back yard. Nice antenna!

AMSAT-UK crossed dipole and laptop with FUNcube Dongle Pro+, waiting for 1720 UTC pass on 26 May 2014

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This was an eastern pass, with maximum elevation of 33 degrees, so I placed the tripod along the back wall on the eastern edge of my property. The antenna was up approximately 10 feet/3m, and connected to my FUNcube Dongle Pro+ with 10 feet/3m of coax.

During this pass, I successfully copied and uploaded 56 data packets to the FUNcube data warehouse, and copied portions of 64 additional packets.

Packets captured by WD9EWK's FUNcube Dashboard during 1720 UTC pass on 26 May 2014

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The total is in line with what I had been copying with my Elk log periodic, but it is a lot easier to use the omnidirectional antenna. :-)

This is a nice antenna, and with the FUNcube Dongle Pro+ makes a nice station to receive AO-73 telemetry (and other satellites with VHF downlinks). The cost of the antenna, including shipping from the UK to the USA, is not unreasonable. The antenna is well made, and was easy to assemble even without an instruction sheet with the antenna. AMSAT-UK supplies a length of coax with a PL-259 connector on one end and an SMA connector on the other, to go directly to the FUNcube Dongle, and a USB extension cable to go between the dongle and computer.

I just posted a YouTube video of this pass, showing the FUNcube Dashboard copying the telemetry from the crossed dipole and FUNcube Dongle Pro+. You can see it at: https://www.youtube.com/watch?v=-S6_f59Pchw

73!

[wd9ewk]

I've received some comments via e-mail on my posting here and on the QRZ satellite forum about using the crossed dipole to copy the telemetry from AO-73 yesterday. Since the antenna did not come with any instructions or a sheet with specifications on it, I was able to find more information about it from its German manufacturer, Winkler:

http://www.winklerantennenbau.de/kreuz137.htm

I'll let you run that URL through a site like Google Translate, if you don't read German. It answered some questions I had about it, too.

Along with the antenna, I visited the local radio shop to purchase a mounting kit for the antenna. It does not come with mounting hardware, and I didn't have anything at home for that. This is how I put the antenna on the tripod/mast I already had. I also put an adapter on the antenna to accept coax with a BNC connector. I have standardized on BNC connectors for my satellite gear, and this also let me use a 3m/10-foot length of coax instead of the shorter 2m/7-foot length that came with the antenna. I already had a BNC/SMA adapter on my FUNcube Dongle Pro+, since the BNC connectors are easier for me to work with than SMA connectors.

73!

[wd9ewk]

Today (1 June), I tried copying telemetry and anything else from AO-73 using my FUNcube Dongle Pro+, FUNcube Dashboard, HDSDR (both programs running simultaneously, using the same 145.925 MHz center frequency and 96 kHz bandwidth from the dongle), and AMSAT-UK VHF crossed dipole in one part of my yard. Since the transponder was on this weekend, telemetry would be at the lower 30mW power level. I also set up my two FT-817NDs and Elk antenna in another part of the yard.

WD9EWK's two stations in the back yard for 1756 UTC AO-73 pass on 1 June 2014.

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Toward the left of the photo, I put my AMSAT-UK crossed dipole on my portable tripod/mast, and my laptop was on a chair near the tripod. I ran both HDSDR and the FUNcube Dashboard program at the same time, both using the same center frequency of 145.925 MHz and 96 kHz bandwidth. Toward the right, near a palm tree in the far corner of the yard, is my transmitting station - two FT-817NDs with Elk 2m/70cm log periodic.

During the pass from the two 817s, I heard VE5SWL in Saskatchewan early in the pass. A couple of minutes later, after calling CQ and not hearing any responses, I moved up to hear KO6TZ in California CQing. I worked him at 1800 UTC, for my only QSO on the pass.

After the pass, I checked my laptop with the two programs. HDSDR recorded the 96 kHz passband from the dipole, but the Dashboard didn't decode any data packets. I wasn't completely surprised at that sight, since I have been lucky to successfully copy one or two data packets on similar passes in the past (transponder on, telemetry at 30mW) using my Elk antenna with the dipole and Dashboard. I was able to hear my QSO with KO6TZ when I played back the HDSDR recording.

I will have to repeat this test again, adding my AMSAT VHF/UHF preamp with the laptop and dongle to improve reception using the crossed dipole.

73!

[wd9ewk]

Hi again!

I am still using the VHF crossed dipole, as it has been useful to have in the yard when doing radio work. Just before Christmas, I used it with my laptop and HDSDR to copy the SSTV pictures from the ISS, while using a Kenwood TH-D72A HT and an Elk log periodic antenna doing the same thing (recording the HT audio with a Sony audio recorder). The directional antenna helped get better signals and pictures, but the crossed dipole - on the same 10-foot/3m mast and tripod I previously used - did a good job. Here's a photo of my setup from that afternoon:

WD9EWK's stations for ARISS SSTV reception on 20 December 2014 - TH-D72A HT with Elk log periodic and Sony audio recorder; laptop with FUNcube Dongle Pro+ and HDSDR, AMSAT-UK crossed dipole on 10-foot mast/tripod

ARISS_SSTV_station.jpg (159.25 KiB) Viewed 7026 times

On the evening of 29 December (30 December, on the UTC clock), I was testing a new transmit radio on an AO-73 pass. I picked up a Yaesu FT-897D last summer, as those radios were being discontinued. The FT-897D is a larger cousin of the FT-817NDs I use. On its internal batteries, the FT-897D will transmit at up to 20W. I wanted to see how easy I could use it for satellite work, replacing one of my FT-817NDs for an AO-73 pass that evening.

Out in my back yard, I set up two complete stations...

WD9EWK station on 30 December 2014 - FT-897D/FT-817ND/Elk for TX/RX, laptop with FUNcube Dongle Pro+, AMSAT-UK crossed dipole, and HDSDR for RX.

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On the left, the station I used to transmit - FT-897D for TX, FT-817ND for RX, Elk log periodic. On the right, a laptop with a FUNcube Dongle Pro+ and HDSDR software, connected to the crossed dipole on a 10-foot/3m mast and tripod. This way, I could record my audio from both the FT-817ND (Sony audio recorder, connected to 817's speaker jack along with the headset/mic I used) and HDSDR (it recorded the entire transponder).

Here's a closeup of the receive setup:

Closeup of AMSAT-UK (Winkler) VHF crossed dipole on 10-foot/3m mast and tripod, connected to laptop with FUNcube Dongle Pro+ & HDSDR.

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During the AO-73 pass around 0440 UTC that evening (2140 local time), I worked Wyatt AC0RA in Iowa. This was the first time I worked an SSB satellite from my station, using something other than the FT-817ND as my transmitter. I was able to vary my power between 5 and 10 watts, and on this pass the lower power level (the same level as the maximum power from an FT-817ND) was sufficient. I could simply plug the headset/mic into the FT-897D with the same cable I use with the FT-817ND. The CW paddle socket is the same 3.5mm socket used on the FT-817ND. Other than the larger size and the option to use more transmit power, it was a seamless swap from an FT-817ND to the FT-897D.

After the pass, I took the recording from HDSDR and ran it through the FUNcube Dashboard software. It did a decent job of decoding the telemetry I recorded. Since I did this a few days after working this pass, I did not upload this data to the FUNcube data warehouse.

The crossed dipole remains part of my antenna arsenal, and I'll continue using it for VHF reception.

73!

[wd9ewk]

Hi!

In September, I made another YouTube video where I copied AO-73 telemetry using my FUNcube Dongle Pro+, AMSAT-UK/Winkler VHF crossed dipole, and an 8-inch HP Stream 8 tablet with WIndows 10. The video is at:

https://www.youtube.com/watch?v=xCHa4yEpopE

This was on a Monday morning, when the 145.935 MHz telemetry beacon was on high power. I was able to copy and forward 113 packets from the satellite, and forward them in real time to the AMSAT-UK server.

Since the launch of Fox-1A/AO-85, the antenna has been getting more use with that satellite. I have been testing different HTs with AO-85, and using my Elk log periodic with the HTs. I also like to copy the AO-85 telemetry, so I use an SDR receiver with the crossed dipole to make RF recordings of the AO-85 passes while working the FM transponder with my HT/Elk combination. After the passes, I play the RF recording into the AMSAT FoxTelem software, and upload any received data frames to the AMSAT telemetry server. AMSAT's approach of having (slow-speed) data transmitted along with the FM voice downlink is great, as stations can make QSOs and receive telemetry from the same downlink signal.

73!