Active Loop
Active Loop - (WellGood Loop)
First, a big thank you to George Smart - M1GEO for the information on his website used for this project, as well as supplying me with the PCBs and Binocular toroids .
Please check out Georges web site which can be found here: https://www.george-smart.co.uk/projects/wellgood_loop/
This reason for this project came about when a very good friend and fellow amateur gave me a dead Wallbrook. He thought that the heart of this loop was fried with RF, however the aluminium loop I could use to make another MagLoop (see my Bike wheel).
While looking around on the internet regarding active loops, I came across the very good website of George -M1GEO . His site gave all the information needed, including an offer to supply two professionally made PCBs and difficult to obtain toroids.
I ordered the PCBs and toroids from him which arrived promptly, then set about getting the other components together.
Getting all the components together ready to start. The WellGood Loop and Bias Tee PCB together with Toroids.
The Bias Tee board complete top right and the WellGood Loop board started.
The toroids wound ready to be placed on the PCB with two single turns to be put in T1 after soldering in place. (see Georges excellent directions on winding the toroids)
The WellGood loop PCB completed
Making the Housing
I wanted the housing to be substantially built to support the large aluminium loop which although not heavy would represent considerable leverage at the points where entering the housing.
Having a small length of sturdy tubing with a wall thickness of 6mm and diameter of 60mm I drilled out holes to take the loop and a slot for the BNC plug.
An end cap was made roughly to size and fixed to the end near the loop holes with self taping screws.
The tube was placed in the lathe to tidy up the end cap giving it a nice flush fit.
Using a sort piece of nylon bar, a plug was made on the lathe to fit to the other end. This had a hole drilled in the centre to fit onto a stand, and a securing thumb screw fitted at the side.
Housing completed ready to take the main PCB. The securing thumb screw seen here at the base, making sure the WellGood loop is securely clamped to the stand.
Here can be seen how the main PCB is slid inside the tube. The piece of tube cut out to allow the BNC plug to slide in place, is put back with hot glue before the bottom plug is screwed in place.
Before the main board is put into the housing, the bias balance for Q1 & Q2 is set with RV1 as described in M1GEO web site
Loop connections made before securing the top cap in place.
The WellGood loop PCB securely housed, connected up for testing and use.