Unfortunately, whilst a mobile 2m FM transceiver can cost less than £100 in the UK, a SSB unit somehow costs a minimum of £685 for the FT-857D - but I don't want HF! The top-end VHF/UHF rigs don't bear thinking about: £1795 for the new, albeit very nice ICOM IC-9700, for example.
So, I had a look around at various used transceivers with 2m multimode capability. The FT-857Ds are fairly common on E-bay, but are so sought-after that their used price is not sufficiently below that of a new one. Ergo, there is no sensible point in buying them.
Eventually, I found a very clean ICOM IC-746 for £495 from a reputable seller specialising in amateur radio. That was at least £200 below the used price for the same rig from one of the big radio outlets, so I bought it! It's even being delivered in person by car, so that it won't get thrown around by delivery companies!
The 746 isn't a rig absent of problems, such as a well-known, overheating display screen backlight transistor. But these are minor things that are either inconsequential, or else easily repaired. There are plenty of online videos to guide people like me. My first job will be to add a heat sink to that transistor, so that it helps avoid the problem in the first place.
So, the next step is a decent 2m antenna. Although they are very easy to build, this time I'm going to buy a Innovantennas 10, maybe 12 element LFA Yagi. For 2020, it will beam permanently across the Atlantic.
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| New for 2020: a 10, or maybe 12-ele LFA for 2m DX. |
I'm quietly confident that, armed with some terrain analysis and a good antenna, I might be able to break the Brendan challenge. Some people think I'm stupid, and that enormous ladder Yagis and enormous power is needed for this to succeed.
But look at the terrain analysis for my location (100m up, sloping all the way down to the Irish Sea), which is for a notionally low (3m above ground), 8 element Yagi (largest available under the software), not the intended 10/12 antenna I will eventually acquire. A total gain at extremely low angles of nearly 25dBi! Gain remains above 14dBi until 8 degrees.
In other words, assuming I can get a good 26dBi out of a slightly larger antenna, a sensible input of 25W from the transceiver magically appears as just under 1kW from the antenna. If I make the rig sweat at 90W into the antenna, the effective output rises to 36kW! This is definitely worth pursuing!
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| Spectacular low-angle gain available, even for a modest, 8-ele Yagi. |
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| Terrain in the direction of the US: an antenna on a 3m pole here is effectively 100m high! |
Whilst some think there is too much atmospheric extinction at 2m for low angles to be usable, I have to beg to disagree - based on experience with SO-50 satellite. My best DX with SO-50 came when I worked a Canadian station using a 5W FM handheld into a 5-ele 2m quad; the satellite was computed to be about a degree above the horizon at that point, not allowing for refraction effects that close to the horizon. The fact I could clearly hear the other station on 70cm downlink also means that atmospheric extinction is not a barrier to low angle VHF working.
I'm impressed John, the Icom is certainly a good VHF/UHF transceiver. It's good to have a goal in this hobby. Good luck, 73, Bas
ReplyDeleteJust a thought.
ReplyDeleteIf there is tropo predicted by F5LEN over the eastern Atlantic, it might be interesting to see if you can hear 2m downlinks from satellites when they are below the horizon. It would suggest that there is a duct present to the west of Ireland.
If there is a beacon or steady signal on the satellite, you should be able to see the doppler on say SSB even if you can't hear it by ear.
It might be a way of working out how far the ducts extend to the west.
John, EI7GL
Interesting idea, John. Always nice to get input from people who, unlike me, actually know a thing or two about VHF! Working out the distance of tropo is something I'm very sure I will have plenty of time to do as I wait for something - anything - to happen on 2m!
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