| Author |
Message |
    
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 623
Registered: 9-2004
| | Posted on Saturday, September 17, 2005 - 1:01 am: | 
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i ran across a mod page that must be kind of new because im constantly searching for them.
on this page, the author states that to boost the receive in the 148/2000gtl chassis that you change TR17 (no typo here) to a 2SC2999. all the other info he has is tried and true, but this one made me look twice.
so can you tell me if its just a typo and if TR17 has anything to do with the RF amp section?
you know why im asking you dont you? you will actually open up a radio and try this, or at least check a schematic for me.
so what do you think?
matt |
Yankee
Advanced Member
Username: Yankee
Post Number: 907
Registered: 7-2003
| | Posted on Saturday, September 17, 2005 - 11:27 am: |
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Just looked at Sams Photofacts for the Cobra 148GTL schematic and TR-17 is the second IF Amplifier, 1st and second IF transistors are the same transistor number as TR-14 the RF amplifier, so this could be a good mod. But TR-17 is in the IF stage, although you never know, could be a receive improvement. What is the website? I'll take a look see.
Carl CEF-357  |
Yankee
Advanced Member
Username: Yankee
Post Number: 908
Registered: 7-2003
| | Posted on Saturday, September 17, 2005 - 12:24 pm: |
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Matt: Try to get your hands on Sams Photofacts, CB radio series #249 dated February 1979, this volume has the Cobra 148GTL first model in it. I see the Sams Photofacts for sale on an Internet auction all the time. The #249 index doesn't yet list the volume # for the Cobra 2000GTL. Possible someone on the forum has a more up to date index for the Sams Photofacts and can let you know which volume the Cobra 2000GTL is in. Although volume #249 is good to have for anyone playing with the Cobra 2000, 148GTL, Uniden Grant LT and XL and I believe also the newer model of the Uniden Madison, the basic information is the same for all these radios with very few exceptions. Same idea with volume #179 working with many of the Uniden uPD-858 sideband radios. I own a copy of both volumes and they are both very handy to have around.
Carl CEF-357 |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 179
Registered: 3-2004
| | Posted on Saturday, September 17, 2005 - 12:34 pm: |
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is that the mod that gives you 6db gain on rx?
Kid_vicious ? I seen that mod but it was on the 2000 which is a 148 really.
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Slowhand
Member
Username: Slowhand
Post Number: 80
Registered: 7-2005
| | Posted on Saturday, September 17, 2005 - 2:18 pm: |
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I'm pretty satisified with my 2000's recieve. Mine's too nice to just to do it for curiosity. I think I've got a 148 in the closet hmm... |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1498
Registered: 7-2004
| | Posted on Saturday, September 17, 2005 - 8:57 pm: |
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replacing Q14 with a 2sc2999 is a well known, common mod for these radios, slowhand & fuse. it can POSSIBLY increase gain up to 6db, but it does lower the noise floor, making the receiver hear even better! and i do agree that they have what just may be the absolute BEST receiver of any CB ever made-even in stock form. yes, this mod makes 'em even better! then you take the removed from Q14 2sc1674 & replace into Q19's spot for increased SSB sensitivity. the noise in the receiver gets quieter EVERY time, whether or not a signal receives even a 1/2 S-unit increase, but either way, weak signals are copied like never before! and yes, pay attention when placing the 2999 into the vacated hole. more then once i've put it in backwards! NO GAIN that way! |
Fusebreaker
Intermediate Member
Username: Fusebreaker
Post Number: 185
Registered: 3-2004
| | Posted on Saturday, September 17, 2005 - 9:57 pm: |
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I figured that was a good mod just the vibe i got from it. |
Slowhand
Member
Username: Slowhand
Post Number: 81
Registered: 7-2005
| | Posted on Sunday, September 18, 2005 - 2:55 pm: |
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Now Pat you've got me wanting to take out the 100 case screws on my 2000 lol. |
Yankee
Advanced Member
Username: Yankee
Post Number: 913
Registered: 7-2003
| | Posted on Sunday, September 18, 2005 - 4:01 pm: |
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Harold, the TR/Q 14 mod. was a great improvement on my Grant XL, quieted a lot of noise and brought signals that were in the noise level up to where they were readable enough to carry on a QSO, before they were hardly there. Now I hear stations that I couldn't before I did the Q-14 mod.
Carl CEF-357 |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1502
Registered: 7-2004
| | Posted on Sunday, September 18, 2005 - 5:38 pm: |
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my XL in my mobile can hear what some of the BASE stations around here CANNOT hear. heck, my XL could hear it BEFORE the 2999 mod. of course, most of the bases are using 2995 or GALAXY radios |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 646
Registered: 9-2004
| | Posted on Sunday, September 18, 2005 - 10:46 pm: |
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just looked at my schematic and TR17 is not even a 2SC1674; it's a 2SC1675.
looking at the location of TR14 it is the obvious choice. |
738
Intermediate Member
Username: 738
Post Number: 139
Registered: 7-2003
| | Posted on Thursday, November 15, 2012 - 11:42 am: |
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I really want to do this mod! There is so much conflicting info. here, is it TR17,or Q14? I'm going crazy trying to get Sams 249 to look myself, I can't find any receive mods on my search's either. I have a Cobra 148GTL Philipine model. Any help will be greatly apreciated! |
738
Intermediate Member
Username: 738
Post Number: 140
Registered: 7-2003
| | Posted on Thursday, November 15, 2012 - 4:26 pm: |
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Never mind-finally found the info! |
