KHF950 Retuning Problems

[tonyc69]

Hi guys. Hope this post finds you well. Here's my problems, when the KHF950 is fitted to our Bell206L3/L4, it will start to retune typically 30 mins into flight. Ground functioning tests however are unable to duplicate the same fault. When this same set of KHF950 is fitted to Beech 200 or Bell412, it works perfectly find.

The antenna used in the L3/L4 is wire type, about 22' long & grounded at the tail boom. Antenna feed-thro' has been changed countless times as well.

Please assist.... this thing has been bugging me for years =.='

Thxs

[411A]

Replace all coax and connectors....that should do it, I believe.
Suspect you have an intermittant short somewhere in the coax or their associated connectors.

[happybiker]

Check the bonding between all of the units particularly between the TR and Aerial Tuning Unit. Also carry out a VSWR check to ensure that the system is tuning properly.

[tonyc69]

Hi guys, thxs for the suggestions. Just tried making the output co-axial cable from the PA/Ant Coupler to Ant Feed-thro' as short as possible (approx 8"). The heli have been flying for 3 days now without any complaints yet.... still keeping my fingers crossed.

Best regards.