Greg made a very good comment on the battery voltage issue......The B40 will
show a drop (as do most other variometers) when the voltage gets low or the
battery is poor....I'd be very suspect of the battery
condition..also...check the back-up battery to be sure it's a good
battery.(check the power selector switch on the B40) EXT-OFF-INT
selector....and try the B40 on the back-up battery....if you're still
getting a needle movement on the back-up battery you've isolated the problem
from being the main battery being too low and now are back at it being an RF
problem....It's still a possibility that the factory cable is at fault or
the connector at the radio is not grounded to the shield.
tim

"Greg Arnold" wrote in message
news:2gJXd.37$KK5.7@fed1read03...
The B40 does funny things when the voltage gets too low. Could the radio
transmission reduce the voltage to the B40 below the crucial point?


Tim Mara wrote:
you've got a serious RF problem.....the B40's are very well shielded so
we really never see this on these instruments.....
check all of your wiring and especially Radio antenna cabble to amke sure
these are not paralleled or wrapped around other cables.try re-routing
the cables and if necessary replace the coax from your antenna lead
tim

wrote in message
oups.com...

I have installed a B40. Only while transmitting on my radio the B40
quickly reads +5 kts and then slowly decays back to zero. Is this
normal and can it be fixed? I tried replacing the power lead to the
vario with shielded wire connected to gnd at one end and this actually
made the problem worse.

Any input would be appreciated.