Last week I built this Collinear antenna as published by by @lex_ph2lb .
Here some pictures and practical advice for those who also intend to build this antenna.
For this antenna I used ordinary 2.5mm² installation cable of which the insulation, with each time a small piece, has been removed.
To start with a straight wire I have edited it with a cordless drill; tighten well on both sides and then pull and turn left / right.
You can bend with this handy tool by Mario Zwiers and pliers
Hole at the last bend (top) is soldered with silver solder but can also be done with soft solder
To prevent the middle contact from warping by heat, clamp the N male / female connector to solder the antenna perpendicularly
The loops have an outer diameter of 15 mm and fit into this 3/4 "tube.
My Sirio is being replaced by the DIY Collinear.
Unfortunately, I do not have any measurement equipment except my nodes. In this form, the antenna seems less sensitive than the Sirio.
Before I changed the antennas, I constantly received “strange” node (26011620) SF11, RSSI -103, SNR -16.5. With this DIY Collinear I did not receive any data from this node in the last days …but this afternoon I placed the Sirio again a̶n̶d̶ ̶ ̶i̶t̶ ̶s̶e̶e̶m̶s̶ ̶t̶o̶ ̶m̶e̶ ̶t̶h̶a̶t̶ ̶t̶h̶i̶s̶ ̶n̶o̶d̶e̶ ̶i̶s̶ ̶n̶o̶ ̶l̶o̶n̶g̶e̶r̶ ̶a̶c̶t̶i̶v̶e̶ ̶ … conclusion, sensitivity still has to be investigated.