CherokeeFlyer,
First of all, is it a Quasar or a RD6000? Those are actually 2 different types of radios. The RD6000 is the current 6 channel computer radio put out by Airtronics. The Quasar is one of the first 6 channel computer radios made by Airtronics and can actually be about 10 years old or so.

For your range problem. How is the receiver antenna routed? Is it fully extended away from the receiver, or is doubled up or balled up near the receiver? If this antenna wire isn't fully extended then your range can be reduced.

As Quinn said above, are the batteries for both the transmitter and receiver fully charged.

One word of warning about the crystals. DO NOT remove/replace the transmitter crystal. It is illegal in the US for the end user to change the transmitter crystal. This must be done in an authorized shop that has the equipment to properly tune the transmitter for the frequency it is on. You can replace the crystal in the receiver though.

If these issues do not resolve your problem you may want to consider sending the radio and receiver into Airtronics for service. The service center for Airtronics is top notch and they will go over your radio with a fine tooth comb to make sure it is working properly

Hope this helps

Ken