AmateurLogic.TV Episode 180 is now available for download.

Emile builds a Geaux Baux. Software for NanoVNA analyzers. Dual Band Satellite Yagi, The Sequel.

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In this episode, we join Martin Butler M1MRB, Chris Howard (M0TCH), Martin Rothwell (M0SGL), Frank Howell (K4FMH), Bill Barnes (WC3B) and Leslie Butterfields (G0CIB)  to discuss the latest Amateur / Ham Radio news. Colin Butler (M6BOY) rounds up the news in brief and in the episode's feature is Our Recollections of 400 Shows.

We would like to thank ICQPodcast 400 Club Member Winston Lawrence, KD2WLL, Neil Connor (M6CUE), Malcolm Heath (KS0T), Ed Efchak (WX2R), one-off donors Michael Rosenberg (N9YB), Gary Bridges (WA0VMV) and our monthly and annual subscription donors for keeping the podcast advert free. To donate, please visit - http://www.icqpodcast.com/donate

• New Australian Ham Licences Delayed
• ISS Time Traveller
• Broadcaster Shuts Longwave Radio Transmitter in Iceland
• American Clubs Grow with Collaboration
• Ofcom Plan of Work

 My dad passed while I was at a very young age but through my mom, I learned that he was a Lancaster bomber pilot in England during WW2. I remember asking her questions but she did not know much as he spoke of his time in the war very little. 

What I did know was he was a commercial pilot in Ireland and then joined the Air Force during the war. At the time he was asked to train as a tail gunner as at the time there were too many pilots and not enough Lancaster aircraft. He completed his training but never sat in the tail gunner turret as he was called up as a pilot. That's all I know of his military time but I have always had an interest in that part of his life. When I lived in Ontario just outside Toronto is the home of the Canadian Warplane Heritage Museum. They have one of the very few flying Lancaster bomber aircraft. In the book the sound of the Rolls-Royce Merlin engines of the Lancaster were often mentioned. I can somewhat understand this, when the museums Lancaster was out flying as it did often you could hear the rich sound of the 4 engines.

This brings me to the book I just finished reading called Bacon and Eggs the story of a Lancaster bomber crew. It is a fictional story based on real crew and actual events. This book goes over the events of the formation, training and missions of one Lancaster crew. It's a short read and is available on Amazon as a book and ebook. If you subscribe to Kindle Unlimited then it is a free read. In closing, after reading the book I look at sitting down to a meal of bacon and eggs in a different light now.

Do You Need That Filter?

The Yaesu FT-DX10 comes standard with a 500 Hz crystal (xtal) roofing filter, but offers an optional 300 Hz roofing filter.  Should you purchase the optional filter?

The 300 Hz roofing filter is twice the size of the 500 Hz filter so it must be twice as good right?  

If you casually switch back and forth between the two filters on a noisy band, it sounds like the 300 Hz filter markedly improves selectivity and quiets the noise.  But try this: Select the 500 Hz filter and narrow the bandwidth (using the bandwidth control) to 300 Hz, then switch to the 300 Hz filter. 

When you digitally narrow the bandwidth of the 500 Hz filter to 300 Hz you will "hear" the same reduction in noise as you have cut out 200 Hz of higher frequency sound.  Engaging the 300 Hz filter lowers the volume a bit (3-6 dB) due to insertion loss.  

So what you are actually "hearing" when you switch back and forth between the filters without changing the digital bandwidth is the reduction of the higher frequency noise that can be accomplished using the bandwidth control alone with the 500 Hz filter.

So, from a selectivity standpointthe 300Hz filter doesn't gain you anything over using the digital filtering with the 500 Hz filter.  The real benefit should come in the form of adjacent signal rejection.  So let's look at that.

In the video below I demonstrate the signal rejection of a 40 dB over S9 adjacent signal to a weaker S3 - S5 signal.

From the video you can hear that there is a very small demonstrable difference in strong signal rejection when using the 300 Hz optional filter, but the difference is so small that I doubt many of us would find practical benefit over simply narrowing the DSP bandwidth while using the 500 Hz filter. Even when contesting.  The digital filtering built into the FT-DX10 is really, really good when using the included 500 Hz roofing filter alone.

Yes, I spent the $200 for the optional filter thinking it would help, but I wished I had known what I do now.  I would have $200 for some other nifty radio gadget to spend instead. 

That's all for now.

Lower your power and raise your expectations

Richard AA4OO

https://www.hamradioqrp.com