Van's manifold pressure gauge

I have the Van's manifold pressure gauge in my panel. Installed per instructions, grounded the sheild wire at the guage and left the other end open per installation instructions. I have an Apollo sl-40 radio mounted about an inch under the gauge.

When I press the transmit button for the radio, the manifold pressure guage maxes out. The weird thing is, sometimes it does, sometimes it doesn't. Sometimes if I transmit on a different frequency it doesn't move at all. Then if I switch frequencies, it maxes out again.

I have moved wires, grounded the shield at both ends, 1 end or the other and not at all. I can't seem to figure this out.

I have a friend that has an -8 that does the exact same thing. Any ideas?

My manifold pressure guage is just above the Apollo sl-40 as seen below.

Thanks!

Rusty

Rusty,

The problem is with the Van's gauges - they are not that well made. Mine used to do that, then it quite completely after 400 hours. Someone in England came up with a mod to the gauge internals to stop it happening - but I did not find it a huge problem and just lived with it.

Pete

(See you at GPM at the weekend)

MP Gauge

Thanks Pete!

I called Van's yesterday and they said pretty much the same thing. Their airplanes do it as well, it is RF interference the gauge is picking up from the antenna when transmitting. They say it is no big deal and doesn't hurt the gauge.

See you this weekend.