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500km (310 miles) on the 2.4 GHz and 3.4 GHz Ham Radio bands!

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by VK7HH, Oct 24, 2019.

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  1. VK7HH

    VK7HH Ham Member QRZ Page

    Last night, 22nd of October the Hepburn charts had a prediction of strong to very strong tropo ducting enhancement over Bass Strait. I promptly got in contact with Rod VK3BQJ and Geoff VK3KGR to attempt a contact from Mt.Wellington near Hobart.

    Once I arrived after work (at approx 6pm) I could immediately hear the VK3RGI beacon on 2403.434 MHz, faint but there. Richard VK7ZBX joined me on site and we attempted a contact with Rod and Geoff. Neither could hear us and we even attempted digital to no avail. Convinced that the conditions were there and likely to improve as the sunset, we made a decision to try once more before packing up at 8pm.

    Whilst we waited around for conditions to hopefully improve, we setup 3.4 GHz to monitor the VK3RGI beacon on 3398.434 MHz. With some tweaking and good ears we could at times hear the beacon in the speaker of the radio and could clearly see a trace on the waterfall.

    Then around 7:30pm we got a call from Ralph VK3WRE who said he was intending to go portable to work us from Mt Tassie, 10km west of the 3RGI beacon site and higher. Richard and I decided to wait around and try a contact with Ralph who would take about 30 mins to get to his portable location. By this time the temperature was still 10 degrees, with an apparent temp of 1.4 degrees. Someone who shall remain nameless didn't think it through that wearing shorts would be a good idea! Whilst I put a jumper on, Ralph setup with Dean VK3NFI.

    The beacon was exhibiting QSB fades over a few minutes, it would almost disappear then come back really strong. We attempted 2.4 GHz first and Ralph was a rock crushing signal 5/8. We exchanged details and decided to move to 3.4 GHz. We got the dish setup and roughly aligned (bearing in mind it is rather sharp). Well we didn't need Ralph to have the keyer on long, he was 5/8 again and arguably a better copy with no QSB. We didn't even have to peak the dish!!

    We again exchanged details and decided to extend the national digital record on 3.4 GHz using FT8. I went to fire up the laptop - dead flat! We'd forgotten about it running all afternoon! I quickly said to Ralph I'd go and charge it up the road at the VK7RTC repeater site (lucky I had the keys). 15 minutes later of charge I returned. Ralph had been working several over VK3's on voice and digital.

    Both Richard and I managed a FT8 contact with Ralph and the laptop promptly died 60 seconds after completing the contact!

    This sets new records on 2.4 GHz for VK7 voice and 3.4 GHz digital nationally at just over 500km.

    Thanks to all stations who made the time to participate.

    Hayden VK7HH

    VK2KRR, N0NB, N7UJU and 4 others like this.
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    VK7HH likes this.
  3. VK7HH

    VK7HH Ham Member QRZ Page

  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page


    I haven't looked up what the terrestrial records are here, but just "roving" in VHF-UHF contests I've made solid QSOs on 2.3 and 3.4 GHz out to about 300 km while actually mobile. Well, parked on a hill overlooking the San Joaquin Valley, which is about 400 miles long and very flat, so if you get up on a hill overlooking that and the other rover is also, it's a very clear path. May not be as good as "over water," but maybe close.

    This was running ~10W to a 1m dish on each end. Tropo ducts set up over that valley pretty often, and it's not difficult to catch one.

    I think a lot of hams are missing out on great fun by not playing on the UHF-SHF bands. "Most" may not have a good enough home location to be terribly successful, but the gear is so small that it's easy to take it portable.

    I've found when there's a duct, the higher the operating frequency, the better it works. Sometimes 10.3 GHz will produce stronger signals than 2.3 or 3.4 GHz, using exactly the same power and antenna. And going down below 1.2 GHz, signals get the time you're down to 144 MHz, they can be "gone." All at the same time, over the same path.

    Fun, isn't it?:)
    KJ7OG and K3RW like this.

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