Broadcast - 1 October 2023
They say things come in threes. Well, a month ago Peter VK7KPC brought in a precision Roller Inductor that incorporated a numerical wiper position indicator for us to play with. Soon after that Nic VK7WW posted a picture on Discord of his much larger Roller Inductor, obviously suited for matching when big linear amplifiers were used. Last technical night Stuart VK7ES brought in one of his roller inductors, this one you could easily put your hand and forearm in it up to the elbow! It was very substantial and obviously designed for large RF currents and high voltage use. It is circa 1940, and spent its life in an AM transmitter site operating on the Medium Wave Band and putting out about 5kWatt of power... Although not technically a roller inductor, more of a manually adjust the wiper, rather than turn a handle to adjust. Also in this case it is definitely with the system powered down as the adjuster was a brass knurled knob, no insulation. But after all it was intended for a fixed frequency long term installation.
The last Technical Night saw Peter VK7KPC tucked away in the club radio room engaged in the TestNet session. Needless to say he was using a radio of military origin, a PRC-64, portable transceiver circa 1965. This is one of the radios featured in Peter’s contribution in the June 2022 REAST - DATV experimenter’s night. It is a portable battery powered only transceiver, 5 watts output on CW, with 1.5 watts output on AM and a frequency coverage of 2.2 to 6 MHz. Peter was able to make contacts on both AM and CW. Phil VK7ZPD had the ability to record Peter’s transmissions and post them on Discord. This allowed Peter to listen back and evaluate any changes he made. The one strange thing to see when looking into the radio room was Peter not wearing the usual headphones, but was using a small crystal earpiece, similar type to the ones used on transistor radios back in the 1960’s! But I am assured it is the original part supplied by the manufacturer.
While we are on the subject of Discord, thanks must also go to Phil for stepping in and hosting the TestNet and TechNet session for the night, as Nic VK7WW was unavailable. Phil also maintains the off-air audio feed found on the Discord channel. The audio feed provides an easy way to stay across the net while out and about or mobile, simply by streaming the audio. It allows you to hear all net participants including mainland operators. I believe Phil derives Discord audio from his Hermes-Lite transceiver. This is a low-cost direct down/up conversion software defined amateur radio HF transceiver based on a broadband modem chip and the Hermes SDR project. This is an entirely open source and open hardware transceiver project.
How many of you can remember their first few projects when starting off into electronics and radio? They seem to occupy a special place in your heart! Tony VK7ZTT was lucky enough to have one of his early construction projects still at hand and brought it in to show the troops. The schematic and construction information was published in Radio and Hobbies about 1947, that’s long before it became Radio Television and Hobbies. Tony however didn’t construct it until a couple of decades after publication. It is a fairly standard 4 valve design incorporating the ubiquitous 807 final. The 807 certainly wasn’t stressed as the designed output was for 3 watts AM on the 40 and 80metre bands. As it was built from scratch and not a kit, parts of various ages and condition were sourced from where ever he could find them. Even way back then Tony was obviously meticulous as even the modulation and power transformers were stripped down, sanded back to remove corrosion and re-painted to as new condition. The overall build standard is excellent and certainly way past the rats nest prototype stage. He also had a very creative use of recycled aluminium rack cheeks incorporated into the chassis construction.
The build must have been early on as none of the controls were labelled, not even by using the infamous “Dymo Labeller” where you selected each letter then squeezed it onto a thick sticky backed tape. But then again I am sure, like the rest of us, you wouldn’t forget what each control was used for …. as time goes by I mean! HiHi It was very nice to see an early project that has survived the passage of time as usually the chassis, case and parts had to be sacrificed and reused in the next bigger and better project!
JOTA/JOTI for 2023 volunteers to assist are needed!
The Venue is the NTARC Club rooms, which is the Rocherlea Scout Hall, Archer St, Rocherlea.
The sessions will be on Saturday the 21st of October from noon to 6pm and Sunday the 22nd of October from 10am till 3pm. If you are able to assist for any length of time over the two days please let Peter, VK7KPC or the club Secretary know of your availability or by e-mailing secretary@ntarc.net
QSL cards - Andrew VK7DW, our QSL manager has advised me that there has been a new delivery of QSL cards from Herman. There are deliveries for VK7’s AT, BO, AU, GC, JFD, KPA, KJL, KW, VIP, WW and ZR. If you just heard your call-sign then there are cards waiting at the NTARC club rooms for collection on the next Coffee morning or Technical Night. Thank you Herman for your continued support regarding QSL deliveries.
As always equipment pictures are available on the NTARC Web site under “Blogs” for this broadcast. Now back to the house keeping.
UPCOMING EVENTS
The Club Technical night - The next session will be on Wednesday the 4th of October and will commence at the winter time of 6.30 pm through to about 10.00 pm, at the Club room Archer Street, Rocherlea
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. Why not pop in and join us for a cuppa, there is endless tea and coffee along with biscuits available for a donation.
Club General Meeting – Wednesday 11th October. Held at the NTARC Club Room, Rocherlea Scout Hall, Archer Street, Rocherlea. Meeting commences at 7:30 pm. For those not going to the meeting there is:
The TestNet and TechNet session - TestNet/CW course on 3.580MHz from 7pm till 7.30 pm…. and a TechNet on 3.567MHz from 7.30 pm till about 8.30pm. Your host for the evening will be Nic VK7WW.
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.
