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Posted by Glenn on January 26, 2026 at 03:33:12.
In Reply to: Re: I cannot beleive the noise level posted by Ed Holland on January 25, 2026 at 15:56:33.
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Thanks Ed, I once had an epiphany about many small audio transformers. I learned that there are many that will pass very high frequencies and do it well. Now I am not talking about SW here. Just past 600 Khz. It opened my eyes. The first thought would be "why such a frequency response when a piece of audio gear doesn't require something that will operate that high in frequency?" I have a collection of them from robbing old junkers. I set up to do measurements and I found many that would perform to higher frequencies. I was astounded. They usually work well into the VLF region and some of them have the approximate impedance ratio. They are overwhelmingly cheap too. Some of them have multiple taps. One thing I keep thinking is build your stuff based on rejection. AM radio hoses me here because I am close to a major metropolitan area. I have a 50,000 W blowtorch within 15 miles of me. SDR's of course don't tolerate MW well and I just keep thinking do what you can to keep this out of your wiring. Design the antenna and matching transformer to be inefficient when it comes close to MW. You can go on Amazon and find all kinds of "low noise" preamps. They may have a response of .1 Mhz to 6 gigahertz. A person sets their self up for all kinds of odd acting harmonics when buying their way out of the need for easy preamps. I just wish I could find something that is designed for what I want and nothing extra. That's were effort comes in.
When I was young I worked for a telephone company. They had frequency selective voltmeters that I could never think of affording. Now their all in the trash and I wish I had them!
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