Question about Heidemann Radio chime set HX One

The product description states: Compatible/expandable with all HX devices and further down ..... 256 transmission frequencies. The specifications state: Frequency 0.43GHz. We need a replacement hand-held transmitter. The following item numbers are listed on our defective hand-held transmitter: HX 70394, 70800, 70801, 70802 and the frequency 433.92MHz. We ordered based on the specification. On the set supplied with Art. No. 70800, the transmission frequency is 256. Before we unpack the following question. Are our old HX receivers (433.92MHz) compatible? (Can they learn)?