Broadcast - 4 February 2024
This week’s Club Technical night was started off by Peter VK7KPC. He had recently received a commercially made HF amplifier that he purchased from E-bay. It did not sport a manufacture’s name, but the model was OGS-50W, suitable for 3 to 21 MHz and most likely 50 W output. The external extruded die-cast case and overall finish was that of a very neat unit. It comes with its own plastic transport case that is clip fastened on all sides and would be at least “shower” rated for water resistance. This was a nice addition to be included with the purchase.
The design is based around a pair of IRF530 N-Channel power MOSFETs for the output devices. It certainly isn’t a complex design but probably a good building block with suitable output filtering added.
Even with the lid off, your first glance was of a nice printed circuit board. However once your eyes start to wander around the board taking in the construction, that’s where the illusion is shattered! I fully understand that we all have to learn to solder sometime in our life……but this is commercial equipment and they really shouldn’t have used a 120 Watt Birko iron to flick solder onto the circuit board from across the room to make the joints. Peter came prepared with a series of close up photographs for those of us with less than perfect vision. The soldering to say the least was interesting! Thank you for bringing it in before you started the clean-up. All you need now Peter is time, de-solder wick, flux and solder to redo every single joint to make it usable.
Hindsight is a wonderful thing. Maybe we should have been warned when it was noted that even the name had a missing letter. There was no “R” in Amplifier.
Peter also had a handful of small Directional Couplers from Satellite Systems for our perusal, some of which have been taken by Tony VK7ZTT and Lionel VK7ZLB. They are taking them home for a bit of “Test and Measurement” to ascertain some of the devices characteristics, we will be interested in the results.
Peter also brought to our attention that during his regular checks of WSPR and particularly the 10 Metre band he had become intrigued by one particular call sign. Initially emanating from south of Western Australia and slowly changing its grid square location over the last few weeks. Evidently it was a Research vessel that had been working around Antarctica and was heading to Hobart before continuing on.
For those using FT8 and WSPR you may know of or even have worked the Antarctic Research station with the call sign DP0POL (Delta Papa Zero Papa Oscar Lima). The equipment operated by Andreas DL3LRM (Delta Lima 3 Lima Romeo Mike) is on board the German research ice breaker “R V Polarstern” , docked in Hobart on Wednesday. This ship regularly visits the Antarctic and this trip left Cape Town on 25th of November 2023. A link to the ship and expeditions can be found in the text version.
Antarctica 2023/2024 – AWI Polarstern Expeditionen
The web site is well worth the visit and the daily log is not limited to research postings. They even covered the “Open Heart Surgery” that had to be performed…….. granted, it was on one of their four diesel engines to replace a faulty head gasket but it was accomplished with the ship riding 3 metres of swell!
If you are near the Hobart area you will be lucky enough to see the ship in the flesh. Hopefully they will be able to collect their “Fresh Green Salad”, as stated in their blog, while in Hobart.
For those present at the club rooms, Lionel VK7ZLB gave us a mini presentation on his recent Summer VHF/UHF Field Day escapades, including photos. He took us through his temporary portable set up that he established on the Northern side of Mt. Arthur. He used a small non-guyed mast that would have been suitable for balcony mounting to attach his antennas. On this, was attached his array of Yagi antennas for the 6m, 2m, 70cm and 23cm amateur bands. The 6m Yagi was connected to his IC7300 with the remaining three Yagis connected to the IC 9700. Lionel remotely located his 23cm preamplifier and Power Amplifier directly below the 23cm Yagi to minimise signal loss. A rechargeable battery bank and solar panels completed the set up as well as some creature comforts from home.
Lionel’s location was very close to the site of the original PMG/Telecom tower that was the Tasmanian end of the Victorian-Mainland radio link. So he was at least pointing in the right direction for some contacts. He had a very busy week end. Apart from local contacts Lionel had success working club groups VK3ER/P at “Wombat State Forest and VK3KQ/P at “Field Day Hill” both approximately 495km by grid square path as well as club group VK3III/P at “West Ararat” approximately 590km. There is going to be some interesting results when all the log sheets are processed.
Lionel finished off the evening with a discussion on losses within coaxial cables, covering foam and solid insulators and the advantages of remotely mounting the preamplifier and Power Amplifiers close to your 23cm Yagi antenna.
We will leave the remainder of the Technical night including Trevor’s baking dish, Peters weather satellite testing and Ross’ “Hello Sailor” till next week’s broadcast.
Errata on News item
Before we go I must make a QRP correction. Unfortunately it’s not the correction that’s small, half a statement this scribe made last broadcast was wrong!
Nic VK7WW did indeed make a QRP contact earlier but it was with Jordan VK3ACU and not Keiran VK3BTV!! Sorry fellows, but at least the QRP contact was successfully made on 80 metres CW both only running 100mW transmit power. The contact was still made between their home states, well done fellows!
As always, but this time if you have a strong stomach and wish to see how not to solder, pictures will be available on the NTARC Web site under “Blogs” for this broadcast.
UPCOMING EVENTS
TestNet and TechNet session - Every Wednesday, TestNet/CW course on 3.580MHz from 7pm till 7.30pm…. and a TechNet on 3.567MHz from 7.30pm till about 8.30pm. Your host for the evening will be Nic VK7WW.
Coffee Morning - held every Friday in the NTARC Club rooms. Time is from 10am to noon and we look forward to seeing you all there. So why not pop in and join us for a cuppa, there is endless tea and coffee along with biscuits available for a donation.
Annual General Meeting & General Meeting - Wednesday the 14th February 2024 at the NTARC Club Rooms, Rocherlea Scout Hall, Archer Street Rocherlea commencing at 19:30 hours (7.30 pm).
Club Room Technical night session - The next session will be on Wednesday the 28th of February and will commence at the usual time of 6.30 pm, running through to about 10 pm, at the Club room Archer Street, Rocherlea.
Finally - A reminder to all members that if you have any items of news you would like added to our weekly roundup, no matter how trivial, then please email them to the Secretary at the following address news@ntarc.net all items to be received no later than 5pm on the Friday prior to the Broadcast.
That’s all folks,
73 from Stefan, VK7ZSB, Secretary NTARC Inc.
