My cobra 2000 gtl

[red97k1500]

Small update, I was able to find a used factory frequency display for it.

Now I just need to finish recapping the radio.

Also I have noticed the power output is not spread evenly between channels 1-40, the closer I get to channel 1 the more power it puts out, which is about 9 watts on am and 12 on side band.

 

[kopcicle]

Also I have noticed the power output is not spread evenly between channels 1-40, the closer I get to channel 1 the more power it puts out

Does the VSWR remain more or less constant ?

 

[red97k1500]

Does the VSWR remain more or less constant ?

Yes it does.

 

[kopcicle]

Well then , seems a bit of a massage is in order.
First you need a service manual.
Then you need proper non magnetic, non metallic, ceramic tools.
Then you need an external, large face RF power meter.
...and more than the average amount of patience.

I have the manual...

 

[Handy Andy]

+1

 

[red97k1500]

+1

Well then , seems a bit of a massage is in order.
First you need a service manual.
Then you need proper non magnetic, non metallic, ceramic tools.
Then you need an external, large face RF power meter.
...and more than the average amount of patience.

I have the manual...

thanks to both of yall I have a copy of the service manual that I downloaded a year ago.

but on an unrelated note I do need a copy of the cobra 29 service manual or the alignment procedure. im still going to do an alignment on the cobra 29 that yall helped me get working a little while back. Then im not going to take on any more radio projects for a while. Because I don't truly have the ability to fix them on my own with out help from the members of this forum. I really do appreciate any and all help I receive.

 

[Handy Andy]

@red97k1500 - I know the issues around new projects - we're here to help...

@kopcicle - where would you like us to start?

 

[kopcicle]

..Refer to manual,
Check driver bias, set to 30ma
Check final bias, set to 60ma

On channel 19, AM, VR10 maximum, tune L47, L47, L48, L46, L45, L38 for peak. Keep keydown short, 10 seconds max, 10 to 50 seconds between keydown.

If greater output on channel 40 repeat tune on channel 15
If greater output on channel 1 repeat tune on channel 25
if still lopsided it gets a little more complicated.

 

[Handy Andy]

And too...

Check Case ground to Board ground - should not be a short - but will read 10K ohms or so, then that is fine...

Back out Case to Board screws,

• look under them - where they were seated
  • shine a light to see if white corroded or cloudy / cold solder joint - reflow the pad if you need
• - also they come with "RF bypass" caps to take off RF may need to reheat solder on those leads...
• - check panel to case screws too...don't leave anything to chance.

​

When you said you the had issue of "looking longer" (more power) to the lower side of frequencies, I remember having a radio with goofy board screws - This is part of the clean up process.

 

[red97k1500]

Small update, last weekend I completely recapped the main board of the radio.

Tomorrow I guess I plan on doing the dreaded counter recap.

I also need to follow the instructions kopcicle left for me.

And Andy I will back the board screws out and retighten, and reflow any pads as necessary. That should keep me busy for a little while tomorrow.

 

[Handy Andy]

Thanks but seeing you also have a 142 - just remember that your LEFT hand DOES NEED TO KNOW what your RIGHT hand is doing...

You have enough on your plate - so if we DON'T hear from you - we know you're out having fun tinkering...

 

[357magnum]

Andy ,

 

[Handy Andy]

Touche!

I'll take that one on the chin...​

- to 357...