Confusing electrical accessorie issue

[Pix]

Hi guys, I hope someone could help me out. On my last trip away I noticed that when I hit the transmit button on my UHF the reading on my egt gauge zeros out. I thought it could've been a voltage or earth problem so among other things the other day, I switched the active and negative for the UHF to the 2nd battery. That way they're on separate circuits (except common earth but in spread apart places), and I I was hoping this would solve the problem. But not, it didn't work.
The egt gauge still stays 'on', so backing light stays on and everything, but just drops to zero whenever I transmit. Sounds like a petty problem, but it's a problem none the less. Once I've finished transmitting the gauge will go back to normal with reading my egts like nothing's happened.
Does anyone have any idea where I can start looking for a problem??
Cheers

 

[equipt]

What sort of gauge is it? as in Digital or analogue. and where is it mounted in relation to the UHF?

 

[d22dave]

Your ariel might be earthing, Check the cable fitting at the back of your uhf , when you push it together with the center solid wire and the braided outer i had trouble the first time i redid mine

 

[Jason]

Have you run the antenna cable next to the EGT sensor wire through the firewall/into the engine bay?

When you are transmitting you may be inducing a voltage into the sensor wire because they are too close.

 

[d40ryan]

Have you run the antenna cable next to the EGT sensor wire through the firewall/into the engine bay?

When you are transmitting you may be inducing a voltage into the sensor wire because they are too close.

if this was the issue wouldnt it be while receiving aswell?

 

[terra88]

unplug the aerial from the back of the set and see if it still does it. That will eliminate an aeriel or lead problem.

 

[Pix]

Cheers guys, the aerial cable runs through the opposite side of the firewall compared to egt, I'll unplug the aerial and see what happens. I think it's digital internals on the gauge, simple 3 wire job. I'll check it out tomorrow morning when I get off work. Cheers heaps for the replies.

 

[Jason]

if this was the issue wouldnt it be while receiving aswell?

No, they produce the most power when transmitting.

 

[Cooper]

Pix did you solve this? It may be a series circuit randomly occurring or something to do with the return path forming a series circuit. Ah the wonders of electricity!