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Why you need a low pass filter when using a splatter box amplifier
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too bad he didn't show what it would do with the low pass filter...
His testing is flawed. Please see the thread below.
https://www.worldwidedx.com/threads...harmonic-at-2-watts-input.226864/#post-618039
If you watch most of these type video's on youtube, you will find most are flawed...
I'm sure he will see it eventually. CB techs have a group of followers that want to believe what makes them feel good about the money they've spent. What I have to say has no value to them.
I guess he will see it but then again trying to contact him lately seems to be almost impossible. Although he does seem to answer certain questions and comments on his YouTube page.
Somebody asked that question on his YouTube page and his answer was:
MikesRadioRepair 1 day ago
It would basically look like the radio when transmitting without the amplifier. It would greatly attenuate anything over 30MHz.
I don't know that I can put any of this to rest but I will at least inject some perspective. First I want it known that I like mikes videos, I like Mike. I think Mike may have gotten his description of what is happening out of context a bit, But the end result is still the same but it should have been described as trash in trash amplified out! Anyway the image below I think puts it in perspective.
Image shows radio harmonics fall nearly perfect in line with amplified harmonics.
1 bottom line on spectrum scope is simple ground noise
The 2-second line up is radio harmonics
3 third line at the top is radio harmonics simply amplified by the linear.
I don't agree with the idea that the amp is generating all these harmonics and I may be that Mike just misspoke to put it in political noise and he may rethink that at some point. I can tell you that after bench testing literally thousands of radios and amps the image below is not the exception but was often the RULE.
Image shows radio harmonics fall nearly perfect in line with amplified harmonics.
1 bottom line on spectrum scope is simple ground noise
The 2-second line up is radio harmonics
3 third line at the top is radio harmonics simply amplified by the linear.
I don't agree with the idea that the amp is generating all these harmonics and I may be that Mike just misspoke to put it in political noise and he may rethink that at some point. I can tell you that after bench testing literally thousands of radios and amps the image below is not the exception but was often the RULE.
Yes, I like Mike as well. I did not post this to make fun of Mike or slight him in any way.
FWIW I have a 1.2 Kw Larcan television transmitter power module that has been retuned for 6m. Because of it's original purpose it is super clean. Tests have been done, and are available somewhere on the web but I cannot be bothered to search for it at the moment. Those tests show that if you insert a low pass filter between the radio and the amp and PROPERLY drive the amp the output will be super clean as well. Most (amateur) radios today are fairly decent in harmonic suppression and adding a filter simply ensures spectral purity and inserting one between the radio and amp allows it to be smaller as it need only handle driver power and not the full output. Properly designed and operated amplifiers will not generate harmonics on their own but if wideband enough they will certainly amplify any harmonics they are fed with.
Just because somebody critiques one of Mike's videos doesn't necessarily mean that they don't like him. I think most if not all of his customers would agree that Mike is an excellent tech.
I have an extra Bencher YA-1 filter I should try between the radio and amp. Already have one on the output side of the amp. Thanks for the tip.
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