In this blog post, I present details of my Cascode IF amplifier with AGC function. The IF amplifier constitutes as a practical module for my HF multi-mode radio transceiver, which I call the "Irwell HF Transceiver".
My version of the Cascode IF amplifier is based on Wes Hayward's (W7ZOI) & Jeff Damm's (WA7MLH) as presented in QST magazine December 2007.
As I mentioned in my previous blog post, I have been developing a high-performance HF multi-mode radio transceiver based on a series of modules that can be upgraded or improved over time.
For this blog post, I present my multi-mode audio amplifier subsystem, which handles the receive audio for the various modes of operation.
For some time now, I have been developing a high-performance HF multi-mode radio transceiver based on a series of modules that can be upgraded or improved over time.
The modular approach has some great advantages and makes it easy to upgrade the transceiver or carry out repairs. There is, however, a negative effect of adopting this approach in that I find myself constantly changing things and wanting to try different ideas and ways of doing things.
Suffice to say my "Irwell HF Transceiver project" is very much a labour of love and a long-term project that is often sidelined while I moonlight on other projects.
I am for ever the optimist that my "Irwell HF Transceiver" will one day be finished so I will continue to add new additions and make improvements!
Welcome to part 6 of my Allstar Link node build.
In
this instalment the project finally comes together with the boxing up of all the various modules and parts that I covered in my previous blog posts.
To enclose the project, I decided that I wanted to keep everything screened to minimize the possibility of unwanted interference in the shack. You may remember in part 4 of my build I commented that there's a reason computers are built into metal boxes!
Welcome to part 5 of my Allstar Link node build.
If you read part four of my node build, you probably arrived here expecting to read a blog post covering the grand boxing up of the project! Fear not, this is just a short interlude and the boxing up will now commence in part 6.
If you are not aware of what a buck converter is, it is a type of switch mode Power Supply; they are highly efficient when compared to traditional linear voltage regulators.
The buck converter module that I will be referrincing is shown below and can be purchased from eBay, AliExpress and many other online sources for less than £2.
Welcome
to part 4 of my Allstar Link node build.
In
this installment I will prepare some additional components in preparation for casing the project up.
In the last installment, I covered modifying the popular CM108 USB sound module for use with the Allstar Link Node and I remembered that I had used the CM108 in a digital mode interface that I designed and built back in 2018. Below is a photo of the interface completed.
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| Click for a larger image |
Welcome
to part 3 of my Allstar Link node build.
In this instalment I will start working on the CM108 USB sound modules and show you how to modify one for use with an Allstar Link node. The module forms a link between the modified Baofeng radio transceiver and the Raspberry PI single board computer.
The CMedia CM108 is a highly popular single chip USB audio solution. All essential modules are embedded into an LQFP 48 pin package. The chip includes a dual DAC, earphone driver, ADC, microphone booster, PLL, voltage regulator and USB 2.0 compliant transceiver.
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| Shown enlarged, the actual IC is 7mm by 7mm | |
Before my blog ventures into anything of a technical nature, I thought it would be fun to briefly document how my journey into the world of electronics and radio all began.
In 1972 I was 8 years of age and had a great fascination for batteries and bulbs, I purchased a PIFCO torch from the local TV rental shop, which gave me hours of fun, especially when equipped with a fresh set of batteries on a smog-laden foggy evening. It was a great thrill to shine the torch beam into the depths of "pea soup". I have indifferent childhood memories of the "Big Smoke" a period when everyone had coal fires, polluted the atmosphere and a had a coal storage bunker in the back yard or garden!
British coal miners went on strike in January and February 1972 for 47 days and the UK was declared in a state of emergency. Britain experienced regular and lengthy power cuts during the seventies, which put the nation into darkness. I remember my parents rationing the use of candles in fear that they would not be able to buy more and the PIFCO torch I used as a play thing became a necessity, providing much-needed light in the pitch black of night.
We felt blessed to have a Parkray coal fire, which served not only as a means to keep us warm but as a means to cook beans on toast during the dreaded power cuts when our electric cooking became a mere piece of furniture.
On December 7th 1972, I witnessed the launch of Apollo 17, this was NASA's final Apollo mission and the crew made a historic journey into space for a record 12 days returning to earth on December 19th.
During 1972 I also embarked on a journey myself and one that would catapult me in to a whole new world... Okay, my journey was not as exciting as the Apollo spaceflight but a mere stroll down to the local newsagents but what followed was tinkering bliss.
