Back in the mists of time, I believe it was July of 2021, Branch 05 facilitated its first 2 metre band, filter building session. Keith Birse ZL4JA (pictured below) had devised a filter, constructed on a tiny PC Board, which could improve the performance of cheap 2 metre handhelds, of Chineseium construction.
Although Keith is officially retired now, he is well qualified to have devised this bit of kit, having had a background of working for Tait Electronics for much of his life after completing his NZCE at Upper Hutt. Coming up with new projects and building them up, is what keeps the light shining brightly in his eyes nowadays.
Small cheap radios like Baofeng, Bofung and Wouxun generally work fine on repeaters but when folks are trying Simplex and especially when attached to larger antennas getting far more signal than they’re designed for, at the edge of their receiving range, much of the stray signals getting through are from the FM Broadcast band (88 to 108 MHz). The July session was fully booked and ran highly successfully, so names were taken. A list was formed. Then another round of Filter building was arranged. For some of the participants, this would be the first time they’d ever used the tiny Surface Mount Devices (SMD).
Indeed in the first course, some of the participants had never soldered ANYTHING before. An introductory evening and “soldering school” is therefore held on the Friday night beforehand. Saturday is the main Filter construction day and then Sunday morning for finishing off, including tuning the filters using a VNA (Vector Network Analyser) and then installing the unit into a small case. The finished unit looks neat in a smaller-than-matchbox case. An SMA to SMA fly lead is required to link it to a radio. The latest course had 6 participants, and Keith was assisted by a couple of volunteers with SMD experience. Thanks go to Keith, his helpers and all the participants. Also for the committee of Branch 05 for helping to facilitate this event. Hopefully we’ll soon be hearing a few more Simplex calls on the VHF band as folks experiment with just how far a Baofeng can go.
Words & photo’s by Catherine ZL3CATH
