denon tuner

i recently purchased a t 1800 dab tuner this keeps cutting out for 20 to 30 seconds with the supplied indoor aerial ber 0.0046 tried putting my dab portable in same room this still works when tuner has cut out.fm band works fine took unit back for exchange just the same.purchased adab loft aerial BER 0.0000 even when cut out  .no better  sent unit to denon for checking came back just the same.just before sound comes back on the station name flashes off and back on again.sound is fine when its on.HELP i am stumped.