MT2000 Jedi VHF - RX Processor noise - Ground problem?

[g8tzl2004]

I have recently acquired a VHF Front LCD MT2000.

The radio was manufactured in 1994 but is in near mint condition. In general, the radio is performing well and has a hot receiver.

Using an external antenna, all RX signals are clean. However, on weaker RX signals using the SET TOP antenna, I can hear some internally generated low level processor noise. But when I squeeze together the radio and battery at either the bottom or middle of the radio, the processor noise disappears.

I guess the problem is a poor contact between the shields and ground? I had a similar problem with a HT1250 and cleaning up one of the ground tags helped to significantly lower the noise level. I would say the HT1250 processor noise is still actualy worse than the MT2000 but the MT2000's low level processor noise does disppear completely when I squeeze together the radio.

Does anybody know where I should look for the poor ground contact? Hopefully this a common problem easily cured by cleaning up a couple of specific ground tags? You would think that a heavily used MT2000 might have screening issues but as my MT2000 is in mint condition you would perhaps expect no ground problems...although as the radio is 18 years old maybe the ground tags have got a bit tarnished.

Thanks

[g8tzl2004]

Any ideas?

[Will]

Maybe the later shield that comes in the Noise Kit for the Jedi radios may help.
As part of a prev mtce, I clean the contacting parts and pads and reassemble the radio.

[AEC]

I use double sided conductive tape, and run a seam along the cover to the frame.
That is for excessive troubles that come and go, so it helps to not to have to remove the frame and tinker over and over again.
There are times I have had to clean and add solder to the edge traces on the controller and RF boards.
once they have been installed for a few years, they get coated with oxides and lose some of the conduction, so I bead solder on these areas and reinstall the boards and meter conductivity from the cover to the boards, and frame to boards. Erratic readings indicate trouble ahead(for me).

[g8tzl2004]

Thanks for the useful feedback.

When I squeeze together the radio by pressing on the bottom front (below the keypad) and battery, the noise disappears. Does this give any clues to the likely exact location of the screening problem?..maybe controller board oxidation?

I can hear the QRM on an AM radio and it is at its maximum in the middle of the keypad. Could the processor noise be coming from the keypad electronics? Is there an earthing tag between the keypad/LCD board and the main screening can?

[CircleBat]

just solder the shield onto the board.. easy solution