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LA 425
- Thread starter Delta 1
- Start date
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
how about a couple of pics of the inside?
LC
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
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
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.
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
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