Cobra148gtl final&bias

[Robb]

i know that but this is the only radio i encountered this issue will not work on 2000m unless i ground red wire.

You don't have much of a clue of what you are trying to do. Let me help you then,

When testing current flow - any current - the red wire of your mA meter will ALWAYS go to the power source. Power is FLOWING to the part under test thru the meter and the black lead of the mA meter. In this way the meter can gauge the AMOUNT of current is passing thru to the device under test. Those two posts on the board is the SOURCE current for the driver and final. OK?

Did that help?

 

[kaos513]

You don't have much of a clue of what you are trying to do. Let me help you then,

When testing current flow - any current - the red wire of your mA meter will ALWAYS go to the power source. Power is FLOWING to the part under test thru the black lead of the mA meter. In this way it can gauge the AMOUNT of current is passing thru to the device under test. Those two posts on the board is the source current for the driver and final. OK?

Did that help?

so explain how did i manage to align all 3 basestations i have and 2 other cobra 148 gtl china made on my meter using 2000m ?

 

[Robb]

so explain how did i manage to align all 3 basestations i have and 2 other cobra 148 gtl china made on my meter using 2000m ?

OK; so you do know how to align the driver and final. What is so 'weird about the bias circuit' then? Are there MOSFETs in there? If so; then there is no alignment. All you can do is make sure that the gate voltage on each device is ~3.6v

If you are NOT seeing any bias when testing the 148 as you would a 2000 or 148; then you may have failed components on the board. Bad final, diver, shorted biasing diode(s), VR's, bad solder joints, or even bad bias wires/connectors. There really isn't much to a bias circuit, so you best go hunt for a fault then . . .

 

[kaos513]

OK; so you do know how to align the driver and final. What is so 'weird about the bias circuit then? Are there MOSFETs in there? If so; then there is no alignment. All you can do is make sure that the gate voltage on each device is ~3.6v

If you are NOT seeing any bias when testing the 148 as you would a 2000 or 148; then you may have failed components on the board. Bad final, diver, shorted biasing diode(s), VR's, bad solder joints, or even bad bias wires/connectors. There really isn't much to a bias circuit, so you best go hunt for a fault then . . .

no fault at all trust me.

 

[Robb]

no fault at all trust me.

If that were true, you would have adjusted it and we would not be having this conversation. Nothing weird about a bias circuit unless it was hacked to put a MOSFET in, or there is a problem with one of the components. One or the other.

 

[kaos513]

If that were true, you would have adjusted it and we would not be having this conversation. Nothing weird about a bias circuit unless it was hacked to put a MOSFET in, or there is a problem with one of the components. One or the other.

No mosfet pic below

 

[nomadradio]

GROUND? ! ? !

If you wish to measure voltage, you attach one meter lead to ground.

But here you are seeking to measure current. More to the point, you are breaking a HOT side circuit. To measure current you break the circuit, and complete that circuit THROUGH the meter. Hot side of the circuit to one lead of the meter. The other meter lead goes to the 'broken' connection that you took loose from the "hot" test-point pin on the circuit board. Taking the wire loose from the post breaks the circuit. Then you complete the circuit THROUGH the meter.

Ground has absolutely nothing at all to do with your final-collector and driver-collector current measurement.

73

 

[kaos513]

GROUND? ! ? !

If you wish to measure voltage, you attach one meter lead to ground.

But here you are seeking to measure current. More to the point, you are breaking a HOT side circuit. To measure current you break the circuit, and complete that circuit THROUGH the meter. Hot side of the circuit to one lead of the meter. The other meter lead goes to the 'broken' connection that you took loose from the "hot" test-point pin on the circuit board. Taking the wire loose from the post breaks the circuit. Then you complete the circuit THROUGH the meter.

Ground has absolutely nothing at all to do with your final-collector and driver-collector current measurement.

73

Well i aliagned all other radios using the 2000m scale so it seems this radio may have some driver bias mod or something else?

 

[Robb]

If you aren't going to test any components and insist on maintaining your position; then I am done here . . .

 

[kopcicle]

Test current in series and voltage in parallel . Voltage through the circuit and current through the meter.
These are generalizations with curious exceptions.
Now take two aspirin, and both bias leads off the posts, insert the meter leads between the post and the lead on whatever scale you can get to work and get on with life.
If you are getting no reading then you have a crap meter, blown fuse, no bias or no clue.
If you ever really do want help there is my mobile # , all you have to do is ask. If you want to waste my time don't bother I have the Seattle Mariners for that ...

 

[kaos513]

Test current in series and voltage in parallel . Voltage through the circuit and current through the meter.
These are generalizations with curious exceptions.
Now take two aspirin, and both bias leads off the posts, insert the meter leads between the post and the lead on whatever scale you can get to work and get on with life.
If you are getting no reading then you have a crap meter, blown fuse, no bias or no clue.
If you ever really do want help there is my mobile # , all you have to do is ask. If you want to waste my time don't bother I have the Seattle Mariners for that ...

its cool ill guess keeping my findings to my self the next time