Abstract: A frequency synthesizer loop includes a first voltage controlled oscillator and a first divider circuit for dividing a frequency of an output signal generated by the first voltage controlled oscillator by a factor of N. The synthesizer loop further includes a phase/frequency detector circuit, a loop filter circuit, a summing circuit, a feedforward amplifier, a second voltage controlled oscillator, and a second divider circuit, wherein the second divider circuit divides a frequency of a second output signal generated by the second voltage controlled oscillator by a factor of M. The synthesizer loop also includes a microprocessor for varying the value M in response to a voltage input, such that the microprocessor varies the value of M to keep the first voltage in the middle of a range of the second voltage controlled oscillator.

Abstract: A down reaming apparatus has an upper stabilizer which supports the down reaming apparatus in the bored hole. A plurality of shoe assemblies are radially attached to the hub of the upper stabilizer. The shoe assemblies are biased against a bored shaft wall by pressurized cylinders which allow limited return movement with resistance of the shoe assemblies. A weight assembly comprising a plurality of stacked plates is secured to the frame of the down reaming apparatus and has manways therethrough which allow passage of workers. A lower stabilizer provides additional support for the down reaming apparatus. The lower stabilizer also includes shoe assemblies that are biased against the bored shaft wall by a pressurized cylinder.

Abstract: A down remaining apparatus has an upper stabilizer which supports the down reaming apparatus in the bored hole. A plurality of wheel assemblies are radially attached to the hub of the upper stabilizer. Each of the wheel assemblies has rotatable tires oriented against the bored hole wall, and a rotatable overload wheel which contacts the tunnel wall upon compression of the tires. A weight assembly comprising a plurality of stacked plates is secured to the frame of the down reaming apparatus and has manways therethrough which allow passage of workers. A lower stabilizer provides additional support for the down reaming apparatus. A plurality of wheel assemblies are radially attached to the hub of the lower stabilizer. Each of the wheel assemblies has a rotatable wheel pivotally attached to the lower stabilizer hub and spaced therefrom by a compressible bumper which reacts against the bored hole wall to stabilize the down reaming apparatus.

Abstract: A down reaming apparatus including a cutterhead body and a plurality of arms radially disposed on the cutterhead body with cutter assemblies on each arm. A first arm has a given length and additional arms each are of different length. Arm extenders having cutter assemblies are attached to each arm such that the combined length of each of the arms and attached arm extender is substantially equal. Spacers are attached to at least one of the arms to increase the diameter of the cutterhead in conjunction with the relocation of each of the arm extenders.