Common and not right
Whiskey Charlie said:
I have UMA/Vans analog gauges.
Chuck Stuhrenberg http:rvparachutes.com
Common Common problem.
-First twist the wire pair between the shunt and gauge
-Reroute gauge wires away from other high current wires
-If you have to cross other wired do it at right angles
-Route other wires away (including antenna coax) from gauge
-Consider shielded twisted wire pair (if twisting alone does not work) between shunt and gauge.
Grounding of the shield typically terminates grounds at one end only. However the shielding can be grounded to the airframe at both ends (local). Do not tie the shield into any other ground wire. You don't want to create a loop. Grounding both ends in this case will not be an issue and should produce good results and recommend grounding the shield at both ends for this application. Multi grounds are problematic for audio and power grounds, but again this is not the case.
The gauge also as someone stated pegs when you TX on the COM. Van's response was "It's OK and normal".
The Tach and MP gauge are also known to do this also.
I helped a friend and fixed the problem, but forgot what one thing or combo did the trick. You may also may try (if you have to) make a copper/brass shield behind the gauge, if the above easier steps don't work. This gauge is subject to EMF big time.
I am just curious, why are you tuning the ALT off. If you are using an internally regulated ND and turning it on/off while it is running under load, it is a good way to damage it. George
