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

LA 425

Discussion in 'General CB Services Discussion' started by Delta 1, Feb 12, 2018.

  1. Delta 1

    Delta 1 Member

    Joined:
    Mar 11, 2016
    Messages:
    43
    Likes Received:
    4
    Can anyone give me any information on this amp.. picked it up today.. works great, can't find any information on it.. TIA 73 IMG_20180211_210653783.jpg


     

  2. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    2,836
    Likes Received:
    1,069
    I believe that these were made by the same guy that made the messenger amps, but don't have any more info that that.

    how about a couple of pics of the inside?
    LC
     
  3. tba02

    tba02 WOOF

    Joined:
    Jan 26, 2014
    Messages:
    566
    Likes Received:
    315
    The amp was designed by a guy named Steve Canfield (based in southern California at the time). He also made (or had his designed copied after he left) the TX Eight Hundred, TX Five Hundred, TX Six Hundred, TX-600, LA-900, and TX-300 (and several others) using a similar case. I know there was a point where his partner took over the builds but I don't know exactly when that was.

    The TX Eight Hundred / LA-900 was a 1x4 (2SC2290 x 2SC2879). I have can't confirm the TX Five Hundred / TX-600 but if I had to guess, they are 4 x 2SC2879 transistor amps.

    I haven't ever seen an LA-425 before. It would be nice to see the inside and/or determine it's configuration.

    A little more from Steve is at the bottom of this page -
    http://www.bunkerofdoom.com/lit/cb/linears/solid/Page.html

    Steve also pops into some of the CB swap groups on Facebook from time to time.
    If you use Facebook there is a bunch of information from Steve within the comments and sub-comments of this link (replace the ** with tt) - h**ps://www.facebook.com/photo.php?fbid=1538565736173816&set=gm.1424574424288154&type=3&theater
     
  4. Delta 1

    Delta 1 Member

    Joined:
    Mar 11, 2016
    Messages:
    43
    Likes Received:
    4
    pictures aren't too good.. but here they are 73 ☺
    IMG_20180212_152439507.jpg IMG_20180212_152427497.jpg IMG_20180212_152427497.jpg IMG_20180212_152507816.jpg IMG_20180212_152439507.jpg IMG_20180212_152439507.jpg
     
  5. Delta 1

    Delta 1 Member

    Joined:
    Mar 11, 2016
    Messages:
    43
    Likes Received:
    4
  6. Tallman

    Tallman W9WDX Amateur Radio Member, KW4YJ EXTRA class

    Joined:
    May 1, 2013
    Messages:
    2,362
    Likes Received:
    1,251
    It has some decen
    It has some decent transistors in there, 2sc2879 Toshibas X2.
     
  7. Delta 1

    Delta 1 Member

    Joined:
    Mar 11, 2016
    Messages:
    43
    Likes Received:
    4
    Yes it does, also a 1446 that drives the 2879's , very happy with it..
     
  8. 9C1Driver

    9C1Driver Sr. Member

    Joined:
    Aug 13, 2008
    Messages:
    2,984
    Likes Received:
    730
    Wish it was just a two 2879 setup, looks kinda odd the way that 1446 is just stuck in there off to the right. If it's working ok then good score, I would treat it as a low drive unit.
     
  9. Delta 1

    Delta 1 Member

    Joined:
    Mar 11, 2016
    Messages:
    43
    Likes Received:
    4
    it works great, and it is odd (1446) placement.. 73 Rick
     
  10. loosecannon

    loosecannon Sr. Member

    Joined:
    Mar 9, 2006
    Messages:
    2,836
    Likes Received:
    1,069
    Delta 1,
    thanks for the pics of the amp.

    definitely looks like an old messenger amp.
    tba02 seems to be pretty hip with the history on these.

    It does kind of look like the driver pill (1446) was bodged on at some point, but it could have been like that originally.

    I am not a fan of the 1 driving 2 transistor design, because i think it causes the two transistors to be driven into saturation much too easily.

    my feeling has always been that the 1 driving 2 design was made for watt meter watchers who were really impressed by the "big numbers" from a two pill amp.

    it only takes a watt or so to drive a two pill amp, so why on earth would we try to push a 30 watt deadkey into them?

    my advice is to run it with a VERY low drive. like 1 watt swinging to 4 watts.
    but that's just me, obviously you can run it however you like.

    if you would like to see whether or not you are driving the transistors into saturation, you can try putting a low pass filter between the output of the amp and the input of your watt meter and see if the power numbers go down with it inline.

    if they do, then the bigger numbers you see without it are just harmonics being added together by your wattmeter.

    LC
     

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!