With the current bad conditions the need to run 80m during the day for SOTA activations has caused me to visit antenna options that would allow me to run 80 with a “minimum” amount of wire.
My normal SOTA / WWFF antenna is an end fed of around 25m with a 6m counterpoise, this is then matched to 50 ohm using an external L Match. This configuration is fine on 40m and up, but is too close to a quarter wave length on 80m to match well. Continue reading
After a stop start build, the Miss Mosquito 40 cw transceiver from QRPproject is working.
With the addition of a Freq-Mite from Four States QRP (left) and a Simple Keyer from QRP Kits (right) it is ready to install in its case.
Whilst mono-band transceivers have their limitations for Parks and SOTA, I felt the unique design with the FM receiver chip and its Varactor tuned VFO nicely complemented my other rigs.
The vertical has had a number of runs since the first post.
I have not actively compared its performance to my end fed antenna. But it seems to be no less efficient as I have worked a few JA station on 18MHz when using it.
The design remains similar with the exception of adding a 1:1 current balun. This was introduced to isolate the coax from the antenna system, as I noted some variation in VSWR as the coax was moved. This was discussed here on the SOTA reflector (look for post #7)
I have remained with the3.7m radials but I have increased the number to 8 (yet to be tested).
After reading An experimental look at ground systems for HF verticals (second link below) I may increase that number to 16.
Naturally the internet is most people go to when it comes to research, to date I have turned up three items of interest
Some Rules of Thumb for Ground Radials
I have also found some interesting reading by Rudy N6LF, Rudy has done a huge amount of work with antennas. two articles caught my with regard to radials for vertical antennas;
First one, on this page look for Series of QEX articles on ground system experiments
The summary of these articles are covered in this document Download QST March 2010 Ground Systems
The second one looks at radial length for shorter verticals, one this page look for Are the lengths of radials related to the height of a vertical? to find the article Vertical height versus radial system
I spotted this on the ABC’s news feed and thought it was worth sharing.
Next Fridays forecast below;
I have often thought of adding a vertical antenna to my SOTA kit for DX use.
This interest was re-kindled when I spotted this kit from Qrp Guys.
The kit also generated discussion on the SOTA Reflector here.
After some thought I settle on a vertical that would cover 15, 17 and 20m with 30m as a maybe.
Base of Antenna
Two SOTA’s and a Park
St Mary Peak vk5/ne-001
St Mary Peak is the highest peak in the Flinders Ranges. It is also one of the few SOTA peaks in the Flinders that is accessible via marked walking track.
Whilst it may only 14.6 Km return via the outside trail, it is still a fair walk with two steep sections which involve a bit of rock scrambling.
Whilst planning a family trip to Eyre Peninsula I was looking for suitable sota summits to activate.
One summit stood out, the unnamed vk5/sw-039 this summit is located within the Lincoln National Park VKFF 0286, but behind the lock gate that allows access to Memory Cove.
Gate to Memory Cove