Tag: news

VK6ARN NewsWest for Sunday 19 November 2017

In the news this week, a monster edition of Roy’s Helpline, activation of a special callsign to commemorate the birth and work of “Father of Wireless Communication”, Bob has a wonderful explanation about Foundation Licensees repairing and modifying radios, Glynn has a new radio network for you to explore and Michelle has an update from the Peel Amateur Radio Group.
Thank you for joining us for another edition of the News, produced and presented for Radio Amateurs, sort-wave listeners and you, since 1931, this is NewsWest.
Listen on-air, on-line or on-demand. http://vk6.net/
Producer: Onno VK6FLAB
Duration: 30:58

Foundations of Amateur Radio – #128 – How does a Temperature Compensated Crystal Oscillator work?

You know when you walk down the street and you lift your foot and all of a sudden you realise that you stepped in something and now it’s stuck to your shoe?
I had that feeling during the week.
Last week I mentioned that I had purchased a TCXO, a Temperature Controlled External Oscillator. Lowell NE4EB set me straight by pointing out that XO stood for crystal and that TCXO stood for Temperature Compensated Crystal Oscillator, which then lead me on a merry goose-chase trying to learn about all that.
I mention this because while the stickiness on my shoe kept me busy, it also highlighted that I’m still a babe in the woods on a steep learning curve to knowledge with some roadblocks, diversions and potholes along the way.
That reminds me, if you ever feel the urge to pull me up on something I’ve said, you can email me via my callsign at gmail.com.
So, how does this Temperature Compensated Crystal Oscillator actually work?
Without getting into the circuitry behind the scenes, as I mentioned previously, a crystal oscillates and the frequency is dependent on temperature. Turns out this is a predictable curve, which makes it possible to account for changes in temperature.
In addition to keeping the temperature stable, another way to keep the frequency of a crystal stable is to have an electrical circuit that changes depending on temperature and have that create something like an opposing curve, so you can add the two together and end up with a pretty stable frequency. Before you start asking how exactly, let me just remind you of the shoe with the stickiness on it.
In essence you have something like a resistor that changes resistance depending on temperature, it’s a component called a thermistor, and that in turn affects a resonant circuit, also known as an Electronic Oscillator, or LC circuit, which in turn affects the circuit that is driving the crystal. These days most if not all of that is on a chip and you get a neat little package that you can plug into your radio to give it frequency stability and hopefully accuracy.
I did say I was going to talk about accuracy this week, but the doo-doo I stepped in put a swift halt to that. Besides, now I know that there is a thing called a thermistor, the second portmanteau I ever learned, together with Gerrymander, so there’s that – oh, also, Tanzania, Eurasia and Oxbridge.
Back to Amateur Radio. The oven controlled crystal I mentioned last week, they exist in high-end measuring gear, not in the $26 TCXO I have installed in my radio. While I’m on the subject, you can also compensate for temperature with software, using either a purpose built micro-processor, or even the host processor that is using the crystal, but that gets into magic self-referencing voodoo pretty quickly.
And while I’ve been playing, Japan is finally being received here and I heard a station 18656km away during the week. Mind you, AA3GZ in Doylestown, Pensylvania, on the Atlantic Ocean side of the United States was putting out 100 Watts, so there’s that.
I’ll leave you with a thought that I hope to be able to answer next week.
If your radio has a crystal that determines what frequency it’s tuned to, how do you use that to determine the accuracy of the frequency, more self-references, just because I can and besides, I’m a software developer and recursion is part of my make-up.
I’ll give you a hint, it’s not all to do with MHz.
I’m Onno VK6FLAB.

Turkey Day Net 2017 – 23 Nov 2017

It’s time to get ready for the annual Turkey Day net.
It’s time to get your gear in order and start thinking up your excuses for not visiting the mother in law.
We’ll try to use the usual frequencies if the bands cooperate. So, be there or be square.

28.450, 21.310
14.245, 7.200
+ / – QRM
Look For The CW TDN activity -50KHZ
+ / – QRL
From The Bottom Of The Most Used Voice Band

Original Article

RadFxSat (Fox-1B) Launched Successfully, Designated AO-91

The latest CubeSat in the Fox series — RadFxSat (Fox-1B) — launched today (November 18) from Vandenberg Air Force Base in California. The Delta II vehicle lifted off at 0948 UTC.

“Following a picture-perfect launch, RadFxSat was deployed at 1109 UTC,” AMSAT reported. “Then the wait began. At 1212 UTC, the AMSAT Engineering team, watching ZR6AIC’s WebSDR waterfall, saw the characteristic ‘Fox Tail’ of the Fox-1 series FM transmitter, confirming that the satellite was alive and transmitting over South Africa. Shortly after 1234 UTC, the first telemetry was received and uploaded to AMSAT servers by Maurizio Balducci, IV3RYQ, in Italy. Initial telemetry confirmed that the satellite was healthy.”

Original Article

Why not volunteer for the RSGB?

Now is the time to consider whether you could help your fellow radio amateur. In the coming weeks and months RSGB will be releasing details of various volunteer vacancies. These include joining the RSGB Board, becoming a Regional Manager, or taking a position in one of the many committees that are essential to the services […] Original Article

Prepare for YOTA Month

GB17YOYA will be on the air almost every day in December. The call sign marks YOTA Month, December, and will be used in rotation by clubs up and down the country. Several other countries will also be running their own YOTA Month stations. GB17YOTA will have a special QSL card and will be uploading logs […] Original Article

New videos from RSGB

The RSGB has released three new videos of talks from the 2017 Convention. They all link with the RSGB Strategy and you can find them at rsgb.org/strategy-videos. In the first video, RSGB Director Steve Hartley, G0FUW explains about the Strategy itself. The second video features RSGB President Nick Henwood, G3RWF, giving a progress report on […] Original Article

IARU Participation in ITU-Radiocommunication Consultations Called “Mutually Beneficial”

International Amateur Radio Union (IARU) President Tim Ellam, VE6SH/G4HUA, has praised the value of the IARU’s participation over the years in International Telecommunication Union (ITU) International Radio Consultative Committee (CCIR) and ITU Radiocommunication Sector (ITU-R) study groups. CCIR was the forerunner to ITU-R. In an article, “The International Amateur Radio Union and CCIR/ITU–R” in the latest issue of ITU News Magazine (see page 55), Ellam said the IARU has been a “regular contributor” to the CCIR and ITU-R study groups and working parties on behalf of the world’s Amateur Radio community. This year marks the 90th anniversary of CCIR/ITU-R study groups; the IARU was first admitted to the work of CCIR in 1932.

Original Article
Skip to toolbar