2000GTL Low AM peaks-SSB OK

[sonoma]

I have never been able to get 20 watts on AM out of a 148 or 2000. will get about 14 max on AM and 18 to 20 on SSB. you can do a diode mod or do the npc/rc mod to the radio to get a little more out of it. the npc mod intails putting a cap in place for audio and volting the final to 12 volts on AM. you can change some resisters in the audio chain to increase output also. the diode mod I was talking about will give it more swing when done by itsself. do not want the npc and diode mod together.

here is a link to the total package for the 2000 and 148 for the npc mod. it shows to pull tr24 but I do not pull it. I lift the leg of R131 if more audio is needed.
this is just my 2 cents worth for you to look at. he shows about a 20 plus output on peak but I have never gotten that much out of one. and do not try to.the final output has to be peaked with proper equipment before the mod link I left you.

http://www.cbtricks.com/members/kd6tas/npc-1.htm

 

[Eastside]

I been trying to tune on my 2000gtl.....its only doing 6 watts on SB peaks and keys up 2 watts and swings to 6 watts on am...... vr 11 does not change anything on ssb and vr 12 does nothing on am?

 

[GnG8d]

I been trying to tune on my 2000gtl.....its only doing 6 watts on SB peaks and keys up 2 watts and swings to 6 watts on am...... vr 11 does not change anything on ssb and vr 12 does nothing on am?

You might want to try this LINK, unless maybe Seven01 has abandoned this one.

 

[sonoma]

sounds like vr's could be bad. vr 11 and vr12 do not work.you have some thing else going on with low wattage out. could be a weak driver or final. even a bad cap can cause low output. need to check them to make sure they are good.

 

[Eastside]

sounds like vr's could be bad. vr 11 and vr12 do not work.you have some thing else going on with low wattage out. could be a weak driver or final. even a bad cap can cause low output. need to check them to make sure they are good.

AM carrier power vr 10 works......will adjust 0-5 watts.

 

[sonoma]

here is a link to the service manual for the 148 which is the same board as the 2000. see if this helps and be sure to check the bias of the final and driver

http://www.cbtricks.com/radios/cobra/148gtl/graphics/cobra_148_gtl_sm_pg48_pg63.pdf

 

[sonoma]

here is all the links to the manual for the 2000. should have left it for you instead of the 148.

Cobra 2000GTL

 

[Eastside]

here is all the links to the manual for the 2000. should have left it for you instead of the 148.

Cobra 2000GTL

I adjusted bias once before on a radio...but i have a terrible memory.....on your multi meter....what setting do you use and which probe goes where....is it the neg goes to the post or the pos?

 

[Robb]

I adjusted bias once before on a radio...but i have a terrible memory.....on your multi meter....what setting do you use and which probe goes where....is it the neg goes to the post or the pos?

The mA setting. POS lead of the DMM goes to the post on the board and the NEG DMM lead goes to the wire that came off of the post. Trace that feed wire over to the output part of the radio; if it comes from the left side of the radio, it is the driver wire. The wire that goes to the right side of the output section is the final feed wire.

The vr for the driver is on the left side of the board, and the final vr is to the right of it.

Both posts on the board are voltage feeds from the same source; so it does not matter which wire is plugged on what post when you are done.

Turn the mode selector to USB, turn the mic gain to 0, have you DMM in mA mode, key the mic, and then turn the vr until you get the proper reading. Do the driver first; then the final.

 

[psycho]

My Cobra 2000 has variable power and swings to 7 watts on a Bird 43 from a 2 watt key. It'll swing 15-17 watts on a peak meter.
These radios are audio kings but not swing monsters.

 

[psycho]

I been trying to tune on my 2000gtl.....its only doing 6 watts on SB peaks and keys up 2 watts and swings to 6 watts on am...... vr 11 does not change anything on ssb and vr 12 does nothing on am?

Has TR24 been removed?

 

[Eastside]

The mA setting. POS lead of the DMM goes to the post on the board and the NEG DMM lead goes to the wire that came off of the post. Trace that feed wire over to the output part of the radio; if it comes from the left side of the radio, it is the driver wire. The wire that goes to the right side of the output section is the final feed wire.

The vr for the driver is on the left side of the board, and the final vr is to the right of it.

Both posts on the board are voltage feeds from the same source; so it does not matter which wire is plugged on what post when you are done.

Turn the mode selector to USB, turn the mic gain to 0, have you DMM in mA mode, key the mic, and then turn the vr until you get the proper reading. Do the driver first; then the final.

Thanks Robb....you have helped me with this before.....but i do not do it regular and i forget......appreciate the help.

 

[Eastside]

My Cobra 2000 has variable power and swings to 7 watts on a Bird 43 from a 2 watt key. It'll swing 15-17 watts on a peak meter.
These radios are audio kings but not swing monsters.

I got a brand new silver eagle hooked up to it and it swings from 2 watts to 6.

I will check and see if tr24 has been removed.....but the back story on this 2000gtl was it was owned by older couple who bought it...and never really got into the hobby and just cover it with a towel and never used it.

 

[sonoma]

you also might look at the board and see if it is covered in nicotene. this can cause a problem also since it was just setting if the people smoked a lot.

 

[Robb]

I got a brand new silver eagle hooked up to it and it swings from 2 watts to 6.

I will check and see if tr24 has been removed.....but the back story on this 2000gtl was it was owned by older couple who bought it...and never really got into the hobby and just cover it with a towel and never used it.

VR10 will set the carrier power level; right rear side of the board. Use a dummy load and a watt meter and set it for 4w on AM/mic gain @ 0.

http://www.cbtricks.com/radios/cobra/2000gtl/graphics/cobra_2000gtl_sm.pdf