Revisiting a panel meter problem.

[davelectronic]

Some time ago I put together a power supply (linear) and used one of these cheap digital panel Volts Amps meter. This PSU was intended to power a HF linear amplifier. Running it works fine on most loads resistive and inductive, but when it powers the HF linear amplifier the meter display goes iratic and shows values all over the place when the radio and amplifier are keyed up. I gave up on this power supply for a long time, but recently wanted to see if I can resolve the issue. Originally the meter is being powered from itself, so no extra PSU to power the meter. So my question is, can it be possible that the load amplifier, while it pulls the correct about of voltage and current, could the slight voltage drop under load send the volt amp meter into this unreadable state ? Or would an independent power source for the meter resolve the problem, such as an additional plug in power adapter. So completely independent power source for the meter. Or is it more likely to be stray RF energy sending the meter into an unreadable state. I will try an independent power supply to power the meter just to see what happens. But thoughts appreciated. Below is the two meter wiring configurations. The meter in the PSU is wired up from its own supply, so self contained at the moment.

[xrunner]

I bet it's RF coupling making the display erratic, since it happens when you use the linear amp. Might need separate PS, ferrites, or sheilding for the display.

[davelectronic]

Thanks for your reply, yes shielding might work if an independent power source fails. I could solder together a small copper box, and try that. But it still leaves the display open, except for the diffuser plastic panel. Shame really, the meter works fine with all other loads.

[p.larner]

bet its rf,try 0.1uf decoupling caps from all wires to a good ground.