can you try filter this way:
var sURI = 'http://<host>:<port>/sap/opu/odata/sap/ZTESTODATA_SRV/';
oModel = new sap.ui.model.odata.ODataModel(sURI, false),
sap.ui.getCore().setModel(oModel);
var sRead = "/pdfset(customer='" + oTF.getValue() + "')" ;
oModel.read( sRead, null, null, true, function(oData, oResponse){
var pdfURL = oData.url;