Autumn tropo – spotting the signs

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VHF/UHF propagation is roughly seasonal. For example, we know that you’d be unlucky (although not guaranteed!) to have Sporadic E propagation on 2 metres in the first week of June. We also know that typically, tropospheric propagation is an autumn thing. Of course, it can happen at other times of the year, but it seems that the autumn often comes up trumps.

So, how do you spot the signs and make the best of it? And do you need fancy gear, high power and big aerials?

Spotting the signs – well, that can be quite simple. Look out for fog and mist! If you wake up, look out the window and see the world shrouded in mist, it’s probably worth a quick look on the VHF/UHF bands! The ‘dawn lift’ used to be quite well known and certainly we often see some enhancements as the day warms up. An hour or so after the sun rises can see some increased ranges and you’ll often notice the same sort of thing in reverse at the end of the day as the sun sets.

The great thing is that whatever your VHF/UHF setup, you can take advantage of this. If you have a simple handheld, then you’ll find the morning and evening a good time to take your handheld (and dog, if you have one!) for a walk and see what you can hear. You may well hear stations and repeaters coming in from further afield. A simple FM rig and a white stick antenna can yield some interesting results too. Why not program up the various repeater and simplex channels and scan them. You will sometimes be amazed at what you hear pop up for a few moments.

DMR, Fusion or D-STAR can work well in tropo conditions too. Maybe you can setup some digital voice simplex contacts from a high point. It will work very well indeed.

If you have a multimode rig, then you can use SSB or one of the digimodes like FT8 and your range will be greater than on FM. Ideally you will use a horizontally polarised antenna, but use what you have and if it is a vertical antenna you will still make some contacts. On SSB, listen and make some calls around 144.300 and look out for activity around 144.265. On FT8 there is a reasonable amount of activity on 144.174 with stations from all over the country and further afield.

Give it a go and hopefully you will be pleasantly surprised about what is possible.

Look out for those autumn mists!

Tim Kirby G4VXE

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