Diamond in the Sky

AW07AI’ve been meaning to write a follow up to my earlier post about the Feature Tech antenna analyser. The short summary of that post was that when I hooked up the antenna analyser to a mobile whip on a magnetic base, I saw all sorts of SWR values which were often not repeatable and changed even as I was taking my hand away from the meter. I was disappointed with the device.

Fast forward a few weeks, in a QSO with Martin VK6ZMS and he was strongly of the opinion that I was doing myself a disservice by running a mag mount without grounding the antenna to my vehicle close to the base of the antenna. Another clue was one idle afternoon at home, I threw the analyser on my WARG Pogo Stick 2m antenna and it had none of the problems I had seen. The SWR readings were reliable (you could read of a value for a frequency, change the frequency then change it back and get the same SWR value) and did not alter as I handled the coax or moved away from the meter. One of the features of this antenna is that it has an coax choke at the base.

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RTS-SDR Sleuthing

Harvey_SW_HighwayYesterday on the way back from a BRC meeting, I stopped in at Harvey to try and track down some interference we are getting on the 70cm repeater VK6RBY that is located on the scarp just east of the town. Listening on the input frequency 433.650 MHz the squelch was breaking as I entered the town limits. Within a few minutes of driving I’d tracked it down to a particular town block.

I hopped out of my ute and tried to use the scanner to try and narrow it down further – without much luck. I’ll have to come back with a yagi to do any better. Since there seems to be a constant carrier with the occasional burst of pulsing, it’s probably a telemetry device of some sort. Continue reading

The Download

I’ve been drawn away from time playing with radio for a couple of months, working away in another town to backfill someone else’s (harder) job. In addition to the time involved in getting my head around the new job, it means starting from scratch again with antennas etc, and I haven’t brought all my gear so whenever I do have an hour to play, I’ve often not got the tools or equipment I’d like. As a result I’ve been keeping in touch by catching up on a number of podcasts and I thought it might be interesting to talk about a couple of them plus some other ham news sources.

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SSTV

The enterprising ex-secretary of my club, Brian VK6TGQ coordinates an “experimenters net” most Sunday mornings in Bunbury wherein different aspects of Amateur radio are played with. Over the last month or so they have been experimenting with sending Slow Scan TV over 2m simplex. From this distance I have not been involved in this apart from occasionally joining them on the IRC channel to see what they are up to.

The equipment to do this can be pretty basic. They started out just with an app on their phones, to transmit, the app loads the image and plays a series of tones (FSK) as each line of the image is transmitted. If you don’t have a cable into your transmitter, you key the transmitter and hold the phone speaker up to the mic. A similar arrangement is possible for receive – the phone is left near the transceiver speaker and converts the tones (and any nearby noises) back into an image. Crude, but results are possible. A much improved result can be obtained by connecting the transceiver to the decoding device (usually a computer tablet or smartphone). Continue reading

Trans-Tasman Contest

G5RV JnrNow my dipole is up semi-permanently, I can sort of operate every weekend I’m home. I say ‘sort of’ as it’s much noisier here in town than at the lookout where I made my first contacts, and I suspect I don’t get out as well with this little half size G5RV at only 6m high.

I turned the radio on last Saturday afternoon to have a tune around and heard VK6QM calling CQ contest. I wasn’t aware there was a contest on, but when no one else was answering I called back and got a quick lesson in what the exchange was (signal report and contact serial number) and scrawled that and my times on a piece of paper. Continue reading

Contact!

I went out for my first shot of HF operating today had had some success as well as learning a couple of lessons.

The set up was at a local lookout – it has a slight elevation compared to town, it’s out of the Snapped squid polenoise (nearest power-line is about 400m away) and partially surrounded by the salt lake that the town is named for. The lookout has an iron railing that is perfect for strapping my 7m squid pole to. The plan was to hook 20m of wire from that down to the back of the ute and run it as an end-fed.

Lesson 1 – there is only so much tension that can be placed on a squid pole before it snaps.

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Rike RK-560 Frequency Counter

Rike RK-560I got another BF-888S in the post today. This one was $18.03 from ebay seller jeenygq. It continues to amaze me that I can buy a frequency agile 70cm transceiver for less than a packet of cigarettes. My ‘reason’ for needing another one is that in addition to my uncompleted 70cm foxhunt project, I’m starting an AllStar Link Node project. I’m always keen to test eBay purchases straight away while they are inside the 45 day PayPal refund timeline, and this seemed to call for one of my other recent purchases – a Rike RK-560 frequency counter.

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Sky Talker

Ready for actionOn the F-Troop net this morning, VK6AS mentioned there was another good pass of SO-50 today. With last weekend’s mistakes learned from, I had another shot at it. I thought I could hear snippets of voice modulation down in the static when the satellite was still at -5º elevation which seemed odd. It wasn’t until about 40º that I got anything readable, and even then it was only for half a second at a time.

SO-50 passThe pass was almost directly overhead for me, so at the apex I was able to just point the Arrow straight up, and copied VK6AS’s call. I put out a call to him and was thrilled to hear his reply of congratulations. So thrilled in fact that I wobbled the antenna and lost him. I was so frantic from then on trying to find the satellite again that I completely forgot to keep adjusting my downlink and didn’t copy anything for the rest of the pass. Continue reading

AW07A Antenna Analyser

Kitchen DrawerI like measuring things, this is perhaps best illustrated with this photo of the current contents of the second drawer in my kitchen. Apart from the usual cooking implements, it contains an infra-red thermometer, a compass, luggage scales, gas bottle scales, 10.5 GHz dopper speed gun and a Geiger counter. I also own numerous electronic meters of various kinds. My most esoteric measuring device is probably a Brix sugar refractometer (uses the bending of light to measure the concentration of sugar in a liquid).

So it caused great excitement here when my antenna analyser arrived this week. At over $300 it’s my most expensive piece of equipment in the hobby. I purchased it on ebay, from a seller I’ve dealt with before and it took about exactly a month to get here due to some story about the stock they had being damaged. To their credit, they air freighted it when they finally had stock.

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