Students Marine Buoy Actively transmitting on 20m WSPR

By Colin Butler of https://www.icqpodcast.com/

Phil Karn KA9Q, Randy Standke KQ6RS and students at the Mount Carmel High School Amateur Radio Club have constructed and deployed an amateur radio marine buoy, callsign KQ6RS, transmitting 14.0956 MHz USB WSPR. About 700 km off the coast of southern California, the buoy is transmitting WSPR on 20m using the callsign KQ6RS and is being received all over the US and into Canada and Brazil.

The electronics is the 20m WSPR version of the WB8ELK “pico tracker” that has been flown quite a few times (including by us) on long-duration balloons. We removed the solar panels and substituted 21 ordinary alkaline D-cells wired to supply 4.5V. We estimate the battery lifetime will be 6 months.

The basic design was inspired by Bob, WB4APR, at the US Naval Academy. Physically, the buoy is just a 5′ section of 4″ PVC pipe, ballasted at one end to float vertically in the water. The top is closed by a sewer pressure test plug I found at Home Depot; it has a bolt in the centre that acts as a convenient feed-through and mounting point for the antenna, a stainless steel CB whip with a matching network designed, tested and carefully tuned by Randy. We use the sea as a counterpoise, but to avoid direct metal/seawater contact we lined the inside of the pipe with copper tape to form a capacitive connection. We probably spent too much time on this; Randy even modelled the electrical fields in the seawater with a professional RF analysis package.

Checkout the Bouy’s Latest – HERE .

Bartek – MM7AJI Wins WoSARS Construction Competition

Friday the 22nd November saw the annual Construction Competition take place, and it was gratifying to see so many good ‘technical’ entries:

  • BARTEK – MM7AJI – Homebrew High Capacity, used Li-Po, Power and Management Pack – 1st with 167 Points
  • CONG . SWL – Homebrew Capacitor Health Checker – 2nd with 155 Points
  • STUART – MM1ESW – Homebrew Remote HF Loop – 3rd with 146 Points
  • PAT – 2M1CKE – Homebrew Portable Desktop Stand
  • JACK – GM4COX – Homebrew 13cms 24 Element Yagi
  • JACK – GM4COX – Homwbrew 8GHz RF Probe

With a new Club member, Bartek the overall winner.

MM7AJI

Well done Bartek !

This year the Scoring regime slightly changed – HERE. Although the Categories remained the same, the Points awarded to each was changed to give a possible maximum of 100 Points/Judge.

And to this end, our two Judges on the night were ERNIE – GM0EZP and JOHN – GM0XFK. Thanks ‘lads’!

The Top Three – Cong, Bartek & Stuart

This year’s standard of construction was high, but as has been said on other Construction related POSTS , it’s not the most technically complex, beautifully built gizzo that will win, as you can see other factors are taken into consideration. So next year please have a go.

Also, there are some more pictures within our PROGRAMME FORUM’s, the CONSTRUCTION COMPETITION Photo Folder.

Finally, it was good to see Paul – MM7AJE (through the generous help of Bartek popping out to Paul’s QTH) able to attend the meeting following his recent ACCIDENT with a Police van. Well done Paul (and Bartek).

Jack(;>J

GB3HI Has Aerial Change

GB3HI – View Across Lismore To The Mainland – Aerial In Middle – Click Picture

For the last couple of years HI has been suffering a form of ‘BLOCKING‘. This was tracked down to the HI’s collinear and the internal components. Thus required to be replaced.

John – MM0JRM (HI’s Keeper) and Robert – GM4GUF, took advantage of the lovely wx during the last weekend to carryout the replacement. (the replacement aerial was kindly supplied by Paul – GM1YUO Fort William)

In discussion with Robert on 2,  he has supplied a couple of pictures which may give you an idea just how well this repeater is placed to serve the West Coast amateur community.

HI’s Aerial On Side Of Building

And remember, these repeaters have to be paid for both from a material and annual running costs – point of view. So if you do use CSFMG Repeaters then please think about supporting the Group.

73

Jack (;>J

Why Balance Batteries – Specifically Li-Po’s?

 

A question was raised at the Club recently as to why we balance Li-Po’s and not cells such as NiCad or NiMh’s?

I certainly knew it was ‘done-practice’ in order to obtain maximum performance from Li-Po’s, but why not do the same for other battery types?

There is a good write-up in Wikipedia (click the graphic) as to why this is done.

And – the bottom line – it appears, that it could be done with most types of battery packs, which in the end would improve their performance and extend their longevity – just as Li-Po’s.

So now you know!


Edit 05/07/19:

Following on from some questions raised on our Members Forum #73  –  HERE is some additional information about Active Balancing and associated circuits, courtesy of Analog Devices.