Broadcast - 7 September 2025
The Mt. Arthur Repeater site of VK7RAA and VK7RJG was visited last Monday, all Amateur Band services were restored. Unfortunately the CB “Repeater 2” could not be successfully brought back into service and has been removed from site for repair. Thanks to VK7s Tony YBG, David JD, Colin ZCF, Eric ZPE and Andre’ ZAB for braving the cold blustery conditions on the mountain to return the services.
Last club room technical night Colin VK7ZCF, our resident 3D printer expert extraordinaire, brought in his latest endeavours. He needed some 450 ohm ladder line for an HF antenna. Why buy and wait when you can build! So Colin has been busy 3D printing a couple of hundred small spacers. He threading 188 spacers onto a pair of conductors and used a wooden dowel as the designated distance between spacers. After a dab of slow setting super glue to hold the spacer in place on the insulated conductors, he now has 40 feet of magnificent ladder-line. All that remains is the antenna construction and some test and measurement Colin.
For interests sake Ross VK7ALH brought in a Yaesu FT-620. This little unit shows the high level of mechanical precision obtained in mass production of a semi domestic radio that is circa mid-1970s.
This 6 Metre band rig covers from 50 to 54 MHz divided into eight 500 kHz selectable band portions. Check out the picture for the rotating dual coloured white and green disk behind the frequency window to denote the 100s of kilohertz portion of the frequency. Its output may only be 4 Watt AM with 10 Watt SSB and CW but it is certainly sporting classic 70s rectangular push buttons on the front panel. Nice little rig Ross, good luck returning it to full service.
Remember a couple of weeks ago I mentioned that one of our members had gone back to basics.
Nic VK7WW was grinding his own plug in quartz crystals, well not from scratch but trying his hand at shifting the resonant frequency, of a commercially made one, higher to something closer to what he requires.
Well Nic has provided us with an update on some of his endeavours:-
He used a glass plate from an old set of bathroom scales for the very flat sanding surface. A sheet of 600 grade wet & dry was held on the glass with electrical tape. He constructed a jig to test the crystal without having to put it back in the crystal holder after each sanding session. Used 99% isopropyl alcohol to clean the crystal each time it’s tested - wiping it with a ‘magic’ synthetic duster.
After Nic removed the quartz from the “plug in crystal holder” it was placed on the sanding sheet and guided by his fingers to move it in a large figure 8 pattern. Complete say 20 figure 8s at a time, before turning the quartz 90 degrees, repeat turning each time you have done 20 more figure 8s. That way you even out any irregularities on the quartz, every time you complete 80 figure 8s. Then check the frequency in the test jig. Repeat the previous grind and test process again and again and again…. Until you hopefully get to the higher frequency you require.
Now for some statistics: - Nic first standard FT243 crystal was on 3.295 MHz and using 600 grit wet and dry, he managed to take it up to 3.529 MHz. This took him 560 figure of 8s, which provided a shift of 234 kHz !
Nic said “My 6042.5 kHz crystal took all day to get up to 7022 kHz. That’s 980 kHz! It only took 1700 figure of 8’s…and now I have no fingerprints! Had to change the wet and dry sheet. But wanted to prove to myself that I could move the fx almost 1 MHz.”
Check out NTARC’s DISCORD channel for the 27th August, for the full technicolour sequence of pictures covering setup, grinding, test-jig, testing, even the insides of a FT243 plug in crystal. This posting also includes a full description of his successful experimentation into shifting crystals. Thanks for the update Nic, but sorry that you won’t be using fingerprint recognition on your phone for a while, HiHi
This Wednesday NTARC club rooms will be opening up to watch the REAST “How to use your NanoVNA” presentation on Wednesday the 10th of September. Doors will be open by 7:00 pm, with the live REAST YouTube channel on line by 7:30 pm. 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.
Special Club Room night session - Wednesday the 10th. September, live stream of REAST “How to use your NanoVNA”, doors open at 7:00 pm.
Club Room Technical night - The next session will be on Wednesday the 17th of September and will commence at 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 fo
That’s all folks,
73, Stefan VK7ZSB.
