View Full Version : Funkwerk ATR833 tranciever BAT indication

17th Sep 2012, 07:19
We are having an issue with a pretty new ATR833 (http://www.funkwerk-avionics.com/cms/upload/Downloads/Handbuecher/01.1403.010.71e_ATR833-2DS-OLED_OI_Rev2.01_120622_WEB.pdf) in that it is periodically showing "BAT" - indicating an under voltage (and so reduced transmission power). It happened a while ago and it has re-occurred.

Once this is indicated, it will not go away until the master power is cycled. The message appears when starting to transmit, sometimes first time, sometimes in the middle of a flight (but as I say - once it is on it stays on). The reduced transmission power makes the radio unusable. Cycling the master power only seems to remove the indication temporarily - it normally re-appears on the next transmission. Some days its fine, others it happens immediately.

Before the summer it was happening regularly. We sent the radio and power supply back to the supplier who bench tested the radio and said it was fine. We re-installed it with a different power supply and it has been fine all summer but the error has re-appeared. It is very time consuming to swap supplies again (and we don't have any more spare ones) so do you have any other suggestions as to a cause for this or anything else we can look at?

This is in a SA Bulldog (so a 28V main bus). The transceiver wants 13.8V so we are currently using a KA-39 (Bendix / King now Honeywell) voltage converter which was successfully used with a previous radio and is only a couple of years old.

Power requirements for the ATR833 (from the linked manual) are:
13.8 VDC (11 VDC ... 18 VDC)
transmitter: 2.5A
receiver: 0.2A (Standby),max. 0.5A
audio power amplifier: up to 1A
emergency ops, reduced transmitting power
< 11 VDC

I believe that the KA39 offers 1.5A continuous output with 5A occasional (but I can't find a manual for it at the moment).

We have a separate intercom but it doesn't say whether the amplifier is used normally so a conservative estimate from the above data:
transmitter 2.5A + receiver 0.5A plus amplifier 1A = 4Amps @ 13.8VDC (55.2Watts) which should be well within the KA39 capabilities.

Anything else we can check before we take the whole thing apart again? Has anyone else successfully used the ATR833 with a power converter? If so which one? Could this be weather / temperature related in any way (my limited electronics knowledge has been exhausted!). Could the issue be a very short drop in voltage when transmit is used that the ATR833 is very sensitive to? Is there a way to smooth this out?

I'm on holiday at the moment with variable 'net access so I wont be able to reply quickly, but I appreciate (in advance) your comments and suggestions!