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Tucson TADD-1, Руководство по сборке и эксплуатации

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PHASE NOISE

This plot shows the residual phase noise of TADD-1 units.  The blue trace is of a unit built with the MAX477
chips, and the magenta trace is a unit built with the AD8055.

REVERSE ISOLATION

Isolation from an output channel to the input, and from output-to-output is typically greater than 80dB at 5 
MHz and 10 MHz(which may be instrumentation-limited).  Isolation decreases below 5 MHz.

Содержание TADD-1

Страница 1: ...dard is normally in the range of 0 to 13 dBm an adjustable gain control allows the TADD 1 to be used with a wide range of input signal levels The maximum output signal is approximately 12 7 dBm into 50 ohms 2 75 volts peak to peak or 0 97 volt RMS Maximum output voltage into a high impedance load is slightly higher A jumper allows the input signal to be terminated in 50 ohms or to operate at high ...

Страница 2: ...m 15 kohms to 47 kohms These changes substantially increase the maximum gain All TADD 1 units shipped after September 15 2006 include these changed components and all earlier units may be retrofitted by changing the values of R4 R1 and R8 as noted and removing R6 No board changes are required The TADD 1 operates from a single 9 volt regulated power supply so input signals to the MAX477 amplifiers ...

Страница 3: ...isolated fed through a back termination into an isolation transformer As on the input the connector is grounded through a capacitor to further reduce the possibility of ground loops The back termination is a 50 ohm series resistor designed both to match the coax cable impedance and to ensure amplifier stability even when driving a capacitve load such as a long coax cable Because the back terminati...

Страница 4: ... laid out on the circuit board as a 2nd order series input filter The component values suggested in the schematic and shown in the assembly instructions below implement a Chebycheff filter with a center frequency of 10 MHz though other designs can be used Its rejection is greater than 30 dB at 5MHz one half the fundamental and is 35 dB or more at 20 MHz the second harmonic and above See the freque...

Страница 5: ...TYPICAL PERFORMANCE ...

Страница 6: ...nit built with the MAX477 chips and the magenta trace is a unit built with the AD8055 REVERSE ISOLATION Isolation from an output channel to the input and from output to output is typically greater than 80dB at 5 MHz and 10 MHz which may be instrumentation limited Isolation decreases below 5 MHz ...

Страница 7: ...ndpass filter Channels 1 through 3 form a tight group with almost identical phase through the amplifier Channels 4 through 6 show slightly higher delay about 0 75 degrees at 5 MHz much less at 10 MHz I am not sure what causes this slight discrepancy the good news is that the phase across all channels is consistent to well within 1 degree ...

Страница 8: ... retested after circuit changes Maximum input for no clipping at maximum gain 3 5dBm terminated in 50 ohms Gain range with 3 5dBm input 0 8 to 7 7 dB output terminated in 50 ohms Maximum output level into 50 ohms 12 7dBm Maximum output level into high impedance 5 12V peak peak Harmonics Source 6 7dBm Minimum Gain Maximum Gain Second Harmonic 46 45 47 Third Harmonic 54 47 46 Fourth Harmonic 61 55 5...

Страница 9: ...y below If anything is missing contact the TAPR office Refer to the layout diagram for clarification of parts placement All references to up down left and right assume that you are looking at the PCB with the TADD 1 text and copyright notice along the right hand side of the board All components are mounted on the top of the PC board If you plan to mount the TADD 1 using the four corner holes now i...

Страница 10: ...S D1 1 0 5A PICOFUSE F1 7 MAX477 AD8055 IC1 IC2 IC3 IC4 IC5 IC6 IC7 1 LM7809 IC8 7 BNC J1 J3 J6 J7 J8 J9 J10 7 Washer and Nut 1 2 pin header and shorting block JP3 1 2 pin Molex header JP5 1 2 pin Molex connector 2 Molex crimp pins 1 1 R27 8 51 R5 R7 R12 R18 R19 R21 R25 R26 6 100 R2 R3 R16 R17 R23 R24 1 220 R10 1 270 R9 2 560 R14 R15 1 2 5k POT R13 1 2 7k R11 1 10k 1k R4 2 15k 47k R1 R8 1 100k R6 ...

Страница 11: ...mper This will minimize input SWR In this case install a jumper wire across the two pins of JP3 Perhaps install a 51 ohm resistor at R12 Perhaps solder and clip 2 leads Install 100 ohm resistors at R2 R3 R16 R17 R23 R24 These resistors mount vertically The body of the resistor should be next to pin 3 of the associated IC Solder and clip 12 leads Install a 220 ohm resistor at R10 Solder and clip 2 ...

Страница 12: ...to the banded silk screen legend on the PC board If you have never worked with these devices take a look at the photograph showing the banded ends Ok Procedure Install a SA15A TVS diode at D1 Solder and clip 2 leads Next Fuse Installation Ok Procedure Install a 0 5 amp PicoFuse at F1 Solder and clip 2 leads Next ...

Страница 13: ...ltage regulator IC and the negative lead toward the front of the board Solder and clip 2 leads Install a 1 uF 101 at C42 C43 C44 Solder and clip 6 leads Electolytic capacitors are polarized The positive lead goes in the hole on the board marked with a NOTE The orientation of the positive leads are not all the same Be careful The negative or the positive lead may be marked Ok Procedure Install a 10...

Страница 14: ... to insulate your finger from the pins hold the header in place and tack solder one pin Check for proper alignment If alignment is off you can reheat the pin to adjust Once alignment is correct solder the remaining pins and then reflow reheat the first pin soldered Ok Procedure Install the 1x2 2 pin DIP header at JP3 Install shunt and solder all pins Install the 2 pin polarized Molex header at JP5...

Страница 15: ...smoke or smell If anything unusual appears immediately turn off the power Find and correct all problems before continuing Ok Procedure Place the ground lead of your meter on the anode opposite the banded end of D1 This is ground reference for all measurements With the meter set to read ohms check pins 1 and 3 of IC8 These may show a low resistance initially because of charging effects but after a ...

Страница 16: ...ces The small notch in the body is on the end with pins 1 and 8 Make sure the notch on the component matches the one on the silkscreen Do not mount the MAX477 ICs in sockets Using sockets could lead to circuit instabilities Ok Procedure Install a MAX477AD8055 IC at IC2 IC2 IC3 IC4 IC5 IC6 IC7 Solder and clip 42 leads Next Initial Test 3 Ok Procedure If you have an ammeter connect it in series with...

Страница 17: ...e series caps and 120pF for the shunt cap The inductors will be 53 turns on a T 50 2 core Those are shown in the instructions below I have not built this filter see note above so can t guarantee the values NOTE THAT THE SCHEMATIC HAS NOT BEEN UPDATED WITH THESE VALUES Ok Procedure Install a 51 ohm resistor at R21 Solder and clip 2 leads Install a 15k ohm resistor at R20 R22 Solder and clip 4 leads...

Страница 18: ...d proper orientation should be double checked Soldering must be carefully inspected preferably with a lit magnifier If there are any suspicious solder connections reflow the solder and check the result Do this until you are satisfied that the board is OK Ok Procedure Board checked and OK Next ...

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