1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Why you need a low pass filter when using a splatter box amplifier

Discussion in 'CB and Export Equipment and Accessories' started by Unit 194, Mar 4, 2018.

Thread Status:
Not open for further replies.
  1. Unit 194

    Unit 194 Well-Known Member

    Joined:
    Feb 25, 2006
    Messages:
    1,150
    Likes Received:
    264



     
    rabbiporkchop likes this.

  2. jessejamesdallas

    jessejamesdallas Sr. Member

    Joined:
    Apr 4, 2005
    Messages:
    1,349
    Likes Received:
    769
    too bad he didn't show what it would do with the low pass filter...
     
    LeapFrog, Mudfoot and Unit 194 like this.
  3. 543_Dallas

    543_Dallas Sr. Member

    Joined:
    Jul 25, 2011
    Messages:
    2,224
    Likes Received:
    2,572
  4. Unit 194

    Unit 194 Well-Known Member

    Joined:
    Feb 25, 2006
    Messages:
    1,150
    Likes Received:
    264
    I agree!
     
  5. Unit 194

    Unit 194 Well-Known Member

    Joined:
    Feb 25, 2006
    Messages:
    1,150
    Likes Received:
    264
  6. jessejamesdallas

    jessejamesdallas Sr. Member

    Joined:
    Apr 4, 2005
    Messages:
    1,349
    Likes Received:
    769
  7. 543_Dallas

    543_Dallas Sr. Member

    Joined:
    Jul 25, 2011
    Messages:
    2,224
    Likes Received:
    2,572
    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.
     
  8. Unit 194

    Unit 194 Well-Known Member

    Joined:
    Feb 25, 2006
    Messages:
    1,150
    Likes Received:
    264
    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.
     
  9. Unit 194

    Unit 194 Well-Known Member

    Joined:
    Feb 25, 2006
    Messages:
    1,150
    Likes Received:
    264
    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.
     
  10. tba02

    tba02 WOOF

    Joined:
    Jan 26, 2014
    Messages:
    597
    Likes Received:
    359
    "Restricted Mode has hidden comments for this video."
     
  11. OldTech03

    OldTech03 Sr. Member

    Joined:
    Dec 15, 2017
    Messages:
    556
    Likes Received:
    823
    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.
    RADIO HARMONICS COMPARED.JPG
    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.
     
    rabbiporkchop and wavrider like this.
  12. Onelasttime

    Onelasttime Well-Known Member

    Joined:
    Aug 3, 2011
    Messages:
    884
    Likes Received:
    417
    Yes, I like Mike as well. I did not post this to make fun of Mike or slight him in any way.
     
    rabbiporkchop likes this.
  13. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,810
    Likes Received:
    8,236
    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.
     
  14. Unit 194

    Unit 194 Well-Known Member

    Joined:
    Feb 25, 2006
    Messages:
    1,150
    Likes Received:
    264
    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.
     
  15. BBB

    BBB Well-Known Member

    Joined:
    Jan 17, 2012
    Messages:
    744
    Likes Received:
    382
    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.
     
    Captain Kilowatt likes this.

Thread Status:
Not open for further replies.

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!