Broadcast - 18 July 2021
Not much activity in the past week so it is straight over to Idris VK7ZIR to give you an update on Wednesday night’s Club tech session;
“Our Tech Session this time can only be described as a Home Brew special!
In previous reports we have been following Trevor VK7TB’s progress in his building of a linear amplifier using a Russian made pentode. To augment his home brew train of events, Trevor decided to back-track some two or three decades and give a presentation of a previous linear amplifier project which had given service to his 160 metre adventures. These were the days before switched mode power supplies were the order, and thus getting said amplifier into the Clubrooms and onto the display table necessitated the use of two of our strapping members! Suffice to say that the majority of the weight was due to fairly massive power transformers used to provide High Voltage and valve filament supplies. These were both hand wound from scratch. Looking at the exterior of the amplifier, one would think it was a commercial product, such was the finish and quality of construction. After much admiration and discussion of the finer points, the covers were removed (I lost count of the screws!!), and more wondrous construction was revealed. Importantly, all covers could be removed for servicing access, so the basic frame was very strong. On the “Top Deck” were mounted two matched QB 3/300 tetrodes made by Mullard/Philips run in AB1 mode. Power output is 500 Watts with 14 Watt drive. Driving power was provided by a TenTec Orion transceiver. On one side was the comprehensive switching facility using relays to add inductance to match the various bands. These included all of the WARC bands. The two variable air-spaced capacitors were situated on the other side of the valves. Trevor was concerned about the vane spacing of one of the commercial units, so in true amateur radio tradition, he manufactured his own. Turning the unit over, the actual relay switches were visible, as were the many capacitors of the HT multiplier. This was where all other electronics was neatly laid out.
Trevor had also brought in his prototyping rig with the Russian tetrode to show us his progress. The valve has a bespoke cooling chimney with fan cooling you could hardly hear. He has included extra metering on the test bed for measuring all the parameters of the amplifier under test. Definitely standing room only around the table for both displays.
Thank you Trevor for a fascinating example of home brew at its best and your interesting commentary.
73, Idris VK7ZIR”
Just a reminder to all attending the club rooms that we have the Check in TAS app at our club rooms. By registering and using the Check in TAS app we are complying with the Public Health Directions by enabling our members to self – check in at the club room.
This information is stored with the Tasmanian Government for contract tracing if required. The QR code is up and running for members to utilize, with the QR code poster at the sign in table. Members are still able to register their attendance at the club by signing in manually in the attendance book if you choose not to register using the Check in TAS app. Please note though that signing in either by QR code or manually is now a mandated Government requirement. If you fail to do so you expose yourself and your club to heavy penalties. Quite apart from that consideration, we have seen this past week just how quickly and easily the Delta strain spreads. I think it would be a reasonable assumption that some Tasmanians would have been attending the AFL game at the MCG in Melbourne last Saturday night. We shouldn’t imagine for a moment that we won’t see the Delta strain reach Tasmania. Contact tracing is a vital part of the effort to control this disease.
Update on Speaker presentation – in past weeks news I have mentioned that we would be having a presentation at the 14th August general meeting, but things have changed and we now advise, that instead of a presentation at that meeting, as it coincides with the RD Contest, there will be a presentation at the Tech Session on Wednesday 11th August a few days prior to our August meeting.
Subject matter will be, topics and demonstrations on how to use the VKCL program to log the RD Contest, the Contest Rules, and future field days.
UPCOMING EVENTS
SLOW MORSE COURSE – Wednesday 21st July. Your host and teacher is Nic VK7WW. Frequencies and times are the same as were used by Nic for the previous TestNet and TechNet. And if you have forgotten what they were, here they are, 1900 hrs to 1930 hrs on 3.580 MHz and then at 1930hours through to about 2030 on 3.567MHz.
So why not tune in and give it a try. By the end of each week, between Morse Course Sessions, participants may have learned 12 characters. Then it’s time to practice them on air.
Nic will be explaining “how to have a contact” and the procedures and protocols. For those who may want some extra help, this website is reported as being very good. www.morsecodeclassnet.com
TECH NIGHT – Wednesday 28th July at the NTARC Club rooms, 19:30 hours until whenever.. Continuous tea and coffee will be available, although again, a gold coin donation for the evening would be appreciated.
FUTURE EVENTS
TECH NIGHT – Wednesday 11th August at the NTARC Club rooms, 19:30 hours until whenever. Special event on the night will be, topics and demonstrations on how to use the VKCL program to log the RD Contest, the Contest Rules, and future field days.
As always, continuous tea and coffee will be available, although again, a gold coin donation for the evening would be appreciated.
August General meeting – Saturday 14th. Meeting will commence at 14:00 hours (2.00pm). The meeting will be followed by afternoon tea so donations of cakes, slices etc would be appreciated. As always a gold coin or note donation is welcomed to assist in our ongoing costs of running the club.
Equine event – Saturday 28th August, North East Equine Endurance Club, Jolly Lette Memorial ride, Santarena Park, Scottsdale. Plenty of warning to help out on this ride. A look at the Tasmanian Equine Endurance Riders Association website at this time shows there will be an 80, 40, 20 and 5 Km ride. As further information comes to hand I will update this news entry with details of the support NTARC will be providing.
COFFEE MORNINGS – currently held every Friday in the NTARC Club rooms. Catch up time is from 10.00 am to noon and we look forward to seeing you all.
These coffee events in the past have been normally a good opportunity to collect your QSL cards. We currently have no cards awaiting collection.
Please demonstrate your appreciation of all the effort that goes into operating the club and its facilities and other services we provide by joining us at these sessions, enjoying the company, coffee and the cake and leaving a gold coin or two, or even a small bank note, in the jar to assist in our on-going operations. I don’t know of any other venue in Launceston where you can get endless coffee, tea and eats for a donation of this miniscule amount.
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 me at the following address news@ntarc.net all items to be received no later than 17:00 on the Friday prior to the Broadcast.
Your continued cooperation in this regard will be greatly appreciated.
We will bring you all such contributions next Sunday morning.
73, Yvonne VK7FYMX, Secretary NTARC Inc
