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(1) Identifying Stepper Motor Wires: Unfortunately, there isn't any standardization of the wires, but they're not hard to figure out using trial and error. A six-wire motor has two center-tapped windings. Use an ohmmeter to identify the three wires for each winding. The resistance from the CT to the end of each winding will be half the resistance between the ends. Once you have identified the windings, then just hook them up to your stepper motor controller. If the motor hums and doesn't move, then reverse the ends of ONE of the windings and try again. The motor will either turn CW or CCW. If it turns the wrong way, then just interchange the two windings.

(2)Coaxial Dynamics 30uA meter: The bad news is that you're unlikely to find a surplus one. and news ones cost about $150. The good news is that the meter is basically a standard Simpson 4" meter, with standard Simpson bezel. Simpson makes a 25uA standard meter, which you can substitute, although you'll have to label the scale yourself. Pad the meter with a resistor so it reads 30uS full-scale. Alternately, you can substitute a standard round Bird meter. New ones pop up on EBay regularly for about $75, and used ones for less. Finally, you can forget the Bird wattmeter and just use a different wattmeter. You'll save big $$$ that way.

(3)B&W Coil Substitutions: Yes, you can substitute a 6 TPI coil, but I don't recommend it for two reasons. First, the power capability of #12 wire isn't as great as #10 wire, and second, the polystyrene coil spacers won't handle the high temperatures of the specified Lexan spacers. The coil in any tuner is the weakest link, since that's where almost all the losses and heat occur, and it isn't the place to economize. I'd pay the $125 for a new coil, and save elsewhere.

Good luck! - Jim W8ZR

.... I do not have the solenoid, please don't ask, I have no idea where to source..... You can email me at n8bx@arrl.net
73 to all, N8BX

Let me suggest you reconsider your plans to use a 7.5 degree stepper motor to turn the inductor switch. I suspect yuu'd find 7.5 degree motors don't have enough torque-at least for NEMA size 23 motors (or smaller). Better instead to gear down a 1.8 degree motor, so you'll have plenty of turning power. You can download a program for using a stepper motor for the inductor switch, and can patch it for any desired stepper angle. Unfortunately, the demands of my job won't let me provide much 1-on-1 assistance to guys, but the code is thoroughly annotated and understandable, so you shouldn't have much difficulty patching it. Good luck! Jim

MAC N4PMG
N4PMG@MSN.COM
December 19, 2002

PULSOUT 13,10
PAUSE 20

The first number after the PULSOUT is the port on the BS2SX (which you should not change) and the second number is the length of the pulse. For the BS2SX, a "10" corresponds to an 8 microsecond pulse. If you change it, for example, to a "20" (e.g., PULSOUT 13, 20) you'd increase the pulse to 16 microseconds.

The delay between pulses is determined by the PAUSE instruction. PAUSE 20 corresponds to a 20 millisecond delay. If you change it, for instance, to PAUSE 30, you'd have a 30 millisecond delay. Keep in mind that the PULSOUT and PAUSE commands appear in several places in the program. You can find them all by using the search command in the Basic Stamp editor.

I'd recommend you start by changing only the PAUSE and leaving the PULSOUT alone. You can tweak the PULSOUT if you can't fix things using only the PAUSE. Obviously, the more you increase the pause, the slower the motors will turn. You'll probably want to experiment a bit to find the shortest pause that doesn't allow any stepper slipping. Also, make the changes for one motor at a time. After you get the C1 motor just the way you want it, then make the changes on the other motors. -Jim

Here's the procedure: Set the output cap C2 at the values shown in the table for each tap, and the transceiver at the frequencies in the table. Then, keeping C2 fixed, vary the tap position and C1 until you get a 1:1 SWR reading on your meter. That point is the correct tap position. (Hint: when the SWR is 1:1, C1 will turn out to be practically the same value as C2.) This method isn't quite as accurate as the method shown in QST, but should work just fine. -Jim

TAP___ FREQ___ C2(pF)
1_____ 28.0_____ 100
2_____ 21.0_____ 100
3_____ 14.0_____ 110
4_____10.1_____ 150
5____ 10.1______ 105
6_____7.0______ 180
7____ 7.0_______ 115
8____ 7.0_______ 85
9____ 3.5_______ 235
10___ 3.5______ 100
11___ 1.8______ 190

(1) Cabinet: 17"W x 7"H x 16"D. These are outside dimensions. The inside dims of the Buckeye cabinet are considerably smaller.
(2) RF compartment: 16"W x 4.875"H x 14"D (inside dimensions)
(3) Chassis gap: ~2" from chassis front edge to inside front panel (not critical)
(4) RF Compartment & Chassis Vertical Clearances (top to bottom):