Tag: topband

RSGB First 1.8MHz Contest – February

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At the weekend, M0TAZ and myself took part in the first 1.8MHz Contest. We have taken part in these for a few years now, most notably 3 years ago in 6″ of snow, and last year getting the car bogged in the mud. We usually do quite well in the SSB only category, as most participants opt for CW or mixed.

Thankfully this year was mild, and not so muddy. The contest runs from 9PM to 1AM, and we used a top band dipole fed with 300Ω feeder. The centre of the dipole was at 60 ft (18m), and was of course 260ft (80m) long.

The big inverted V.

The big inverted V.

Using an Icom 7100 and 32w (the maximum for this part of the band) we managed to work 60 stations including England, Wales, Scotland, Ireland, France, Netherlands and Germany. Activity from the UK seemed to be low, perhaps due to the contest falling on Valentines day this year.

Loaded Quarter Wave Antenna on Topband

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We went out for some portable operating today, as the weather was nice. Our club has a topband net each Saturday at 2pm and I wanted to try an antenna for the upcoming 160m AFS Club Calls contest. Using Dave M0TAZ’s 18m spiderbeam fibreglass pole as a loaded quarter wave, with an inductor (340μH) towards the top of the antenna. It makes it all a bit critical having the inductor so high, but the big advantage is that the bottom 15.5 metres has a lot of current in it, leaving only the 2.5 metres above it at a high impedance, making a better radiator. Ground was provided by a chicken wire fence, which I have used many times before with good results.

Below is a short video showing the antenna first on 24MHz where Dave is working Bahrain where the vertical was set up close to a ⅝ wave, then afterwards, it’s fully extended with the loading coil 15.5 metres up, making it a loaded ¼ wave for 160m. The antenna was resonant at 1830kHz, a bit low, so the ATU was used. I calculated for 1900kHz, so I guess 70kHz off isn’t bad! It would be easy enough to fine tune it. Lovely day for it, a bit breezy towards the end though!