Amateur radio antennas, circuits, techniques and related topics. By Peter Parker VK3YE/AK3YE.
Newer material appears at https://vk3ye.com and https://youtube.com/vk3ye .
Video describes a magic little IC used as a QRP AM transmitter modulator. You can get good audio even without a modulation transformer.
PS: I've now written six books on various aspects of amateur radio. Whether you experiment with antennas, enjoy QRP or are starting out in radio there's a book for you. Find out more here.
PS: Want to do more with amateur radio? 99 things you can do with Amateur Radio is full of ideas. Available as a low-cost ebook or in paperback, you can find out more here.
Basically they started at 27 MHz then went up to 49 MHz to get away from interference from the then-booming 27 MHz CB radio service (though some of us would have preferred intercommunication with CBs!). Later UHF became cheaper. The USA have the Family Radio Service around 460 MHz while the Europeans have something similar around 446 MHz.
Development was a bit different in Australia. They started on 27.240 MHz in the late 1960s. Often single channel 'handphones' with maybe 100mW output. You needed to have a licence and a genuine purpose to use them. And back then CB radio was illegal (27 MHz was then an amateur band). Pirates either used amateur gear or increasingly common mobile type transceivers (which were often crystal controlled with a few channels).
We got a lot of imported models. They typically had a few crystal controlled channels and were licensed as CB radios. They were the size of a brick with a large antenna, a superhet receiver and squelch.
There were also cheap ones that kids often got as presents. In the late '70s they were on a CB channel with a crystal soldered in (often 27.125 MHz or ch 14). These didn't need a licence as they were low power. They often had a hissy superregen receiver. You could directly talk to CBers but a problem was their receivers were so broad that they'd hear pretty much anyone on the band. So you wouldn't know if they were on your channel or not. But you could still talk to an AM CBer if they were on Channel 14.
Later on, around 1980, the walkie talkies went off the CB channels. But unlike in the USA they still stayed on 27 MHz. 27.145 MHz was the most common frequency, shared with remote controlled toy cars etc. It was the worst of both worlds - their broad receivers were still susceptible to hearing 27 MHz activity but they couldn't hear you to have a conversation. Although that might have been a benefit for anxious parents worried about kids talking to truckies and others prowling the CB airwaves.
A few walkie talkies for 29 MHz FM (just above the amateur band) were sold here. Also 55 MHz, especially by Tandy. And more recently UHF has got cheaper so that's where they've ended up. Australia was a pioneer with UHF CB (477 MHz) and once again cheap walkie talkies can communicate to CBs, reinstating the brief link that was broken after the brief 27.125 MHz years of the '70s.
Getting back to 27 MHz, these videos are a bit more on cheap handhelds.
The handheld below is an early '80s model sold by Dick Smith Electronics. I converted it from 27.145 MHz to 28 MHz amateur (as I had a crystal). But later, after the video was done, I converted it back.
These are really cheap ones. Not even a crystal. You could shout further. Still if you're into bare bones electronic design they could be interesting.
Here's a comparison I did between 1970s, 80s and 90s walkie talkies. Older is better!
What were your early walkie talkie experiences? Please leave them in the comments below - I'd enjoy reading about them!
PS: Interested in antennas? Consider this selection of antenna books. They are affiliate links meaning that I receive a small commission (at no extra cost to you) if you decide to purchase.
The warm weather is back so I've been at the beach. Didn't make any contacts but heard G4AKC working various other VK and ZL stations on 7 MHz. Here's some audio.
PS: Are you interested in portable antennas? If so this book could be just what you need. Available as an ebook or in paperback you can find out more here.
Never done it? It's satisfying! Some tips in this video with a simple project to try.
PS: Ever find a term in amateur radio you don't understand? The Illustrated International Ham Radio Dictionary can help. Available as an ebook for $US 5 with paperback also available. Details in the link.
I've always wanted to transmit with a rig with no transistor (or valve) final amplifier stage. Yesterday I did it using a diode balanced modulator connected must before the antenna. Admittedly it was only a few milliwatts and it was WSPR but the signal was detected thousands of kilometres away.
More in the video!
PS: Interested in antennas? Consider this selection of antenna books. They are affiliate links meaning that I receive a small commission (at no extra cost to you) if you decide to purchase.
Those who have seen my videos will know I've done a bit with magnetic loops. However mine have mostly been lightweight types for QRP and portable operating. If you want to build an efficient loop for home station high power operating you'll need something more solid. One of those who has built such a loop for 80 & 160m is Steve VK5SFA who won a QST magazine award for his design.
Enjoy this QSO Today interview with Steve where, later on, he describes his experience with loops.
PS: Are you interested in portable antennas? If so this book could be just what you need. Available as an ebook or in paperback you can find out more here.
PS: Want to do more with amateur radio? 99 things you can do with Amateur Radio is full of ideas. Available as a low-cost ebook or in paperback, you can find out more here.
An off-beat diversion from radio when the bands are crook is to get a bit of consumer electronics and see if you can make some odd sounds from it.
One can make an amplifier into an oscillator by adding some positive feedback. Even a pair of sweaty hands can do it. Of course for safety's sake one should only do this with battery powered gear.
Another thing you can do is get an electronic toy and connect resistors and capacitors across various parts of the circuit. You'll get some interesting sound effects. Especially if you add variable resistors, light dependent resistors and more.
Anyway here's a few videos on circuit bending I've done.
PS: Are you interested in portable antennas? If so this book could be just what you need. Available as an ebook or in paperback you can find out more here.
I've been trying some simple antennas on 2m lately. There's not a lot of difference between them in the performance stakes. But I though it was worth testing reception of a CW beacon about 400km distance during a band opening.
The antennas featured are a dipole, a 2 element yagi, an oblong loop (1 wavelength perimeter) and an hourglass (2 wavelength perimeter with two loops).
PS: I've now written six books on various aspects of amateur radio. Whether you experiment with antennas, enjoy QRP or are starting out in radio there's a book for you. Find out more here.
When I was younger I noticed that most yagis had approximately equal spacing between the elements.
More recently I've noted very different spacing patterns. For example the outer directors were very widely spaced while the first director was not far from the driven element.
And when I was experimenting with a 4 element beam for 2m directly fed with 50 ohm coax I found I could get a match with wide bandwidth with this narrow driven element/first director spacing. On 144 MHz this spacing is about 10cm or 0.05 wavelength.
Only recently did I find that these types of yagis had their own name - Optimised Wideband Array or OWA for short.
They are easy to feed and have a good bandwidth. The main compromise is you lose a small amount of forward gain.
Anyway here's some OWA links you might find handy for your next antenna project.
PS: Are you interested in more portable antennas? If so this book could be just what you need. Available as an ebook or in paperback you can find out more here.
