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

TS mod v

Discussion in 'General CB Services Discussion' started by dxing440, Apr 20, 2014.

  1. dxing440

    dxing440 Active Member

    Joined:
    Apr 10, 2011
    Messages:
    161
    Likes Received:
    10
    nobody said anything about using the mod v on SSB! just because the radio has SSB don't mean that's what it'll be used on!


     

  2. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    5,907
    Likes Received:
    2,001
    Easy, we got that part.
    OK basically, all I am saying is that the amp you have now would not be my first choice to use.

    Crusher has offered some good advice, you can bias it, that will help clean it up.....

    I dont think there is an easy way to make it do what you are wanting to do.

    73
    Jeff
     
  3. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    3,108
    Likes Received:
    1,709
    The problem with class C is it's too easy to drive into RF cutoff on AM. Once you do that you have destroyed the signal quality. About the only way I would run a "modulator" is with a scope so you can set the drive and bias appropriately. It is the proper setting of drive and bias that will allow an amp that runs less than class AB to sound relatively clean on AM.

    That usually does not happen when the amp is solid state and has no bias at all. When there is no bias at all, you waste too much carrier to bias the transistors on and that means any reduction in carrier during negative modulation peaks can easily hit RF cutoff. Some bias with reduced carrier from the exciter (radio) is the better approach here.

    To be honest, even with adjustable carrier on the radio, a variable attenuator between the radio and amp, adjustable bias on the amp and an intact modulation limiter, it's still a handful to get something like this to run clean. Especially when you consider that it's probably going to get amplified another 10 or 20 db after that stage.
     
    1 person likes this.
  4. RadioGuy772

    RadioGuy772 Active Member

    Joined:
    Dec 30, 2013
    Messages:
    106
    Likes Received:
    42
    I agree with shockwave. The moment that carrier starts approaching a certain amount of downward shift on negative peaks, that transistor is going to switch off and create all kinds of mess.
     
  5. dxing440

    dxing440 Active Member

    Joined:
    Apr 10, 2011
    Messages:
    161
    Likes Received:
    10
    thank God for local radio techs. I appreciate everyone's (opinions)but no answers, but my local technician got me hooked up and its working fine.its all good, he gets paid for stuff like that
     
  6. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    5,907
    Likes Received:
    2,001
    Good Post Shock.
    These little things are really only good for one thing.....wild swings on a wattmeter.
    How do I know?
    Yes back in the day I played with them too.
    TnT ( not the same TNT built now by x force) used to build a small amp called a Super Mod that had 2 MRF 455 transistors in push/pull with passive bias, it worked much better than the Mod V ever did, and could be dialed back easily to drive a bigger amp.



    73
    Jeff

    ♪You Ain't got a thing♫ if you ain't got that swing ♫♪
     
  7. GnG8d

    GnG8d Well-Known Member

    Joined:
    Jun 28, 2010
    Messages:
    2,037
    Likes Received:
    331
    Actually you did get answers, just not the ones you wanted to hear.
     
    3 people like this.
  8. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    3,108
    Likes Received:
    1,709
    If you got a receipt with this repair, could you share what your local tech did to fix the problem? No fancy description required, a simple list of the parts he installed / charged for is preferred and will tell us if it's all good.
     
    5 people like this.
  9. wavrider

    wavrider W9WDX Amateur Radio Club Member

    Joined:
    Jun 2, 2009
    Messages:
    3,311
    Likes Received:
    1,114
    Did your local tech show you on the O scope how clean your swing is?

    Or did your local tech get paid to show you the swing in your thing?

    Most likely he made the customer happy, that is how "Your Tech" makes his money.
     
    1 person likes this.
  10. RadioGuy772

    RadioGuy772 Active Member

    Joined:
    Dec 30, 2013
    Messages:
    106
    Likes Received:
    42
    Me thinks what he means is "the answers I got were either completely over my head. Furthermore, I have no interest in learning what your answers mean. So, what I did, is take it to a guy and while you people said it wouldn't work, he made it "work" by connecting up the two leads, (which I answered on how to do) and powering that sucker up and by golly--more power out. I also got a radiocheck too, and this guy a few miles away on channel 19 said it's wall to wall and tree top tall. So, thank God for local tech who didn't bother me with all of this uncomfortable nonsense, and just hooked it up and stuck to simplicity".

    If I were to take a guess, I do not have a PHD, but that would be closer to the actual and also psychological nature of the actual situation. It is amazing at how some of my customers would rather pass me money, and just have me stick to simple rather than explain things. It's as almost once you break a comfort line then it gets too complicated and they get uncomfotable with you.
     
    1 person likes this.
  11. dave457

    dave457 Sr. Member

    Joined:
    Jan 3, 2009
    Messages:
    798
    Likes Received:
    761
    I'm sure you sound "Grand on the Band"
     
  12. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,856
    Likes Received:
    8,390
    It is quite obvious the the OP has no desire to have a clean signal nor understands the problem with what he has. All he is interested in is making the meter swing. I just wish these people would stop trying to turn nice full carrier double sideband AM into crappy suppressed carrier double sideband AM, which is exactly what they are doing with a low carrier and LOTS of swing. If they want to watch a meter bob up and down go to SSB where it actually works right straight out of the box.
     
    1 person likes this.

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!