There is a wide choice of receivers/scanners available for use with rocket tracking. I use a Yupiteru 7100 Receiver, connected via a 50 Ohm lead to a Sandpiper YAGI-Uda Antenna.
Most standard receivers/scanners should suffice, since the key to obtaining the long range is actually in the antenna rather than the receiver/scanner. An antenna with a large gain enables signals to be picked up at a longer range, however as the gain gets larger, the antenna becomes more directional, so it is a trade off in directionality, antenna size and ease of use against range.
RF Signal Strength Meter
Generally, a signal strength meter on the receiver/scanner is a very good item to look for, and this was one of the reasons I chose the Yupiteru 7100 as the receiver. Many cheaper receivers do not have signal strength meters, and this is definitely something to bear in mind when choosing a receiver. A signal strength meter really does make a big difference for the rocket tracking application.
RF Receiver Sensitivity
The other reason for choosing the Yupiteru 7100 is it has exceptionally good sensitivity compared with competing models, and for receiving faint RF tracking signals from rockets, this is a very useful feature.
As well as having an antenna with an appreciable amount of gain, and a sensitive receiver, it is also possible to fit a pre-amplifier between the receiver and the antenna, to improve the sensntivity still further.