Today I switched to 17m and made a CQ call. VarAC then switched to slot 12 (18108.5 kHz). I soon heard the OA4B beacon on 18110 kHz (CW). That means, Vara can interfere with IBP beacons and be affected by strong beacon signals. We may just be a little too close to the beacon frequency if we use slot 12 and worse if we use slot 13 - 15.