Broadcast - 6 July 2025
We have a couple of items left over from last week’s club technical night, firstly: Colin VK7ZCF brought in a homemade 2 Metre antenna suitable for a handheld transceiver. The actual element was made from 1.5 mm Nitinol wire or as it is more commonly known, memory wire. Nitinol wire is a unique nickel-titanium alloy known for its shape memory effect, meaning it can return to its original shape when heated above a certain temperature. However in this situation its super elasticity property is the important one, making a very flexible antenna that is ideally suitable for portable use. Because the Nitinol wire is also corrosion-resistant it makes it much harder to use what we consider as “normal” solder. However there is a gold and tin solder mix along with a special flux that allegedly makes things easier. The use of gold in the solder mix is starting to sound somewhat expensive though! Colin overcame the SMA connector attachment problem by removing the centre pin, he then ground the nitinol wire diameter down to match the pin size and inserted that into the connector, replacing the pin. To make the whole assembly more resilient he then 3D printed a black plastic ferrule to encapsulate the glued in SMA connector and antenna termination. With a sleeve of thin black heat shrink tubing over the antenna it certainly looks and feels the part.
Colin also has been busy working on an interface module for his battery operated Surecom SS11 Field Strength Meter. He 3D printed a “T” shaped structure, the leg of the “T” incorporates an SMA connector at the bottom, with the top bar of the “T” being tubular in shape. The top half of this tube is removable, uncovering an openable split ferrite core balun. The dozen or so turns wound around the ferrite core is terminate on the SMA connector. With the ferrite core opened a co-axial cable can be placed longitudinal through it and then the top clamped back on. When the module is plugged into the Surecom meter he can get a relative level reading of the common mode current RF energy coming back on the screen of the co-axial cable from his antenna when he is transmitting. Yet another useful little gadget, Colin certainly is getting the most out of 3D printing to assist with his projects.
Ross VK7ALH brought in a “working” item, read that as not in for repairs, but purely for the interest of members. It was an LDG Electronics AT-200 Pro general purpose antenna matcher that covers 1.8 to 54 MHz. Its automatic operation relies on processor-controlled Switched-L tuning and is capable of manual override. Large, easy-to-read LED bar-graphs show forward and reverse power in peak or average mode and SWR. Two power scales are provided: 25 watts and 250 watts. The AT-200Pro requires just 5 watts for operation making it ideal for QRP as well as general purpose antenna matching. A nicely presented and functional piece of equipment Ross. I am not sure if the antenna matcher or the packets of Tim-Tams that accompanied it generated the most attention! Well at least the antenna matcher survived the night in one piece. HiHi.
Last Wednesday evening the NTARC club rooms were opened so members could get together for a live presentation on the REAST YouTube channel, entitled “ChirpSounder Technology”. The doors were opened by 7:00 pm with members soon seated ready for the start of what turned out to be an informative presentation. The production was excellent in the new High Definition. Thank you REAST for the presentation and video stream availability. Local discussions continued on into the evening.
You still have a couple of days - to register for the mid-year club get together held this Wednesday night at the Iron Horse Bar and Grill. If you have made a last minute decision to attend, please notify the secretary or any committee member. See you there.
As always pictures will be available on the NTARC Web site under “Blogs” for this broadcast. NTARC Blogs
UPCOMING EVENTS
On Air Test and Technical Net session - Every Wednesday, Test-Net and CW course on 3.580 MHz from 7 pm, then a Technical Net on 3.567 MHz from 7.30 pm till 8.30 pm. Your host for the evening is Nic VK7WW.
Mid-year Club get together - Wednesday 9th July at Iron Horse Bar and Grill.
Club Room Technical night session - The next session will be Wednesday the 23rd July, from the usual time of 6.30 pm at the Club Room Archer Street, Rocherlea.
Coffee Morning - Held every Friday in the NTARC Club rooms. Time is from 10 am to noon.
Finally – If you have any items of news please email them to the Secretary at the following address news@ntarc.net all items to be received no later than 5 pm on the Friday prior to the Broadcast.
That’s all folks,
73, Stefan VK7ZSB, Secretary NTARC Inc.
