[Lowfer] M0Ayf active loop

[Paul Daulton]

Thos who know me know I am involved in low freq beacon work. While I have had some success transmitting my receiving capabilities have not been first class. This summer my friend Dave WA5WKO installed a beacon at his lake side home near Heber Springs Ar. With a long wire I could copy this beacon daytime for a couple of hours using a TS50 and long wire antenna or PA0RDT mini whip. Dave had similar results at home in North little Rock. We both built large ( 8 and 10 ft dia loops). Dave had very good results with his 10 turn 10ft dia loop. I didnt do so well with my 8ft 14 turn loop. For the last few months I have been plagued with broadband noise from LF to about 5mhz which kills my reception particularly on 80m 4sqrp wed night nets. 

I read about the M0AYF active loop on another site and decided to give it a try. see http://www.pm.keirle.com/3_radio/hf_loop_ant/hf_loop_ant.htm for details. As per the posting it is a single turn loop with a bipolar differential amp of common transistors. Advantage of this loop is lower noise due to the cancelling effect and better signal to noise ratio. 

First results, after connecting the amp to my 14 turn loop I could see the beacon( HSA on 185.304khz QRSS) better than on my longwire or Pa0rdt mini whip. At HF the loop performs well with one turn on 40 and above but not so well on 80. At low freq one turn is no good but with the 14 turn loop I now copy Dave's beacon about 15 db above the noise floor using ARGO and Spectran 24 hours a day. It is not received on the long wire or mini whip. 

I relocated the loop to a spot in the yard that was quietest on my Grundig G6 portable. My lot is 175w X 330ft deep. Power lines are across the street and on the west side, house faces north hamshack is on west end off the garage. New location for loop is on the east side of the house about 90 to 100 ft away from the hamshack. I used 75 ohm cable tv coax to run into the shack. 

Calls to the power co-op havent done any good. Aparently the teenager in charge of answering the phone didnt have a clue about what my complaint was. I have one of those remote reading power meters that I suspect is the problem. Pulling the main disconect doesnt kill the noise so I dont think it is coming from one of our appliances. 

I have tried all sorts of active antennas and loop tuners and this is the best so far. Big advantage is I can go from the 185khz part 15 beacon band to 137khz(2200meters) or 600 meters with out having to retune. 
Looking foward to listening this winter. 

Let me know what you think

Paul k5wms
Paul Daulton K5WMS
beacon WMS 185.302 khz qrss30/slow 24/7
Jacksonville,Ar 72076
em34wu