RaDAR Sprint Equipment Development

Thomas Robinson

My last few RaDAR type outings have been a little disappointing in terms of the results (QSOs) obtained.  


Some years back I played about with DIY magnetic loops and was quite impressed with their performanc . Interestingly, being vertically polarised when set up in a vertical plane, they also benefit from the salt water amplifier effect.  So, this morning I dug out my big DIY loop and gave it a checkout.  All was fine but it is quite heavy.  Manageable, but a bit cumbersome - not something you would want to lug around all day (but for a two hour RaDAR sprint outing, maybe).


Today I paired it with the old and heavy Icom 703.  I walked them to my nearby test site and mounted the antenna on the golf trolley.  At the moment the golf trolley with the antenna mounted is not really a proposition for moving site to site as a single unit, so the trolly was trollied and the antenna was carried on my left shoulder.  The rig was in its carry bag slung around my neck and right shoulder,  A sight to behold!


A bonus of this system is that it is extremely quick to deploy on site - faster than my end fed half wave/golf trolley combos.  Another bonus is that once set up, changing bands is just requires re-setting the variable tuning capacitor.  The big loop I used today is very effective on 20/17/15m and above.  It is acceptable on 40m.


I have attached a chart showing the calculated efficiencies (using the calculator from 66pacific.com). The efficiencies show is how the loop compares with dipoles cut for the bands and deployed at their most  advantageous heights.


Also attached are some photos taken at today’s site and snippets from my QRZ.com log and the RaDAR sport log.


So what next?  Weight reduction - the mag loop, the rig? the battery  and myself if I have to carry it any distance.


Its all go, but enjoyable


73 All. Tom G0SBW