First of all, the DX series have a few improvements to the receiver, although the P.A. units in the radio (power amplifier) still has a very high idling current, and also, a bias source needs to be a low impedance source. The PA unit also has issues with reverse phase currents back into the radio. RCI still hasn't figured this out. Their capacitance values, as well as the types of capacitors used have a bit to be questioned. Alot of power is wasted in heat because of this.
Now, with the Icom 706 MIIG, it's an excellent radio for the price. At HRO, they're down to about 750.00, and you get something you just can't compare with "glorified" CB radios. speaking of HRO, someone mentioned in this thread that some RCI DX series cannot be converted, this is true. All of the RCI radios that seem to be supplied to HRO, cannot be converted to 11 meters.
Off subject, but if you own the 706 MIIG, get the TCXO for it, it improves stability, and it's rock solid if you use it alot of VHF / UHF SSB use.
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