ARLA/CLUSTER: Como calibrar um Analizador de Antenas MFJ-259B

[Paulo Mendes]

Fonte: http://www.rimtai.com.tw<http://www.rimtai.com.tw/chtr/Products/MFJ/Products/MFJ-ANALYZER/MFJ259BCali.htm>



*MFJ 259B Analyzer Calibration*

*This is an MFJ procedure that does not contain any information that would
not be handed out by them. It is easy-access to a test procedure, that is
all it is. It is a shortcut to help you.?/b>*

*This information is here only because it is the correct way to calibrate
the MFJ-259B analyzer. MFJ's first priority is making sure people who can
not send units back to MFJ or who want to verify calibration with a correct
reviewed and edited procedure have something easy to access. MFJ gets all
the credit for this procedure, no one else.*

*It is best that no one copy this, and start handing it out in mass. The
only reason for this is there should be a point of control of information,
so it can be corrected as errors are found.*
*Common Problems* * *

*This family of analyzers is dc-coupled from the bridge to the antenna port.
The bridge detectors are NOT frequency selective, and respond to anything
from minor dc offsets through microwave signals. This causes a potential
problem if there is any voltage appearing across the antenna port, from dc
through microwave. (This is also true for competing analyzers from other
manufacturers.)ôÙhere are multiple reasons why, at the time of design, these
units were dc coupled with broadband detectors. Hopefully someday a higher
cost-design with selective detectors will become available, but for right
now this is all that is available for amateur use.?/p> *

*Because the detector is broadband, and because it is dc coupled to the
antenna, any external voltage across the input port causes measurement
errors. It is the accumulated voltage of multiple sources that is most
important, not the strength of any individual signal. Because of that, large
antennas should be tested at times when propagated signals in the range of
the antenna's response are at minimum strength.?/p> *

* A definite RFI improvement occurs with a bandpass filter, but
multiple-section bandpass filters cause impedance measurement problems.
Multiple-section filters behave like transmission lines of random line
impedances, loss, and lengths as frequency is varied. The best solution is
to use a single-stage bandpass filter and dc isolation on large arrays or
with long feedlines. I often use a good 1:1 isolation transformer for
measurements, and often find a parallel L/C filter (like the MFJ-731 Filter)
useful.? ?/p> *

*The detector diodes clearly stand out as the most easily damaged devices in
the analyzer. If you have a sudden problem, it is most likely a defective
detector diode.?/p> *

*In order for the detectors to be accurate within a fraction of a percent
(one bit), detector diodes must have very low capacitance and a very low
threshold voltage. This means the diodes, through necessity, must be
low-power zero-bias Schottky microwave detector diodes. The same
characteristics that make them accurate and linear cause the diodes to be
especially sensitive to damage from small voltage spikes. ALWAYS discharge
large antennas before connecting them to the analyzer! Never apply external
voltages greater than 3 volts to the antenna port!*
* **How This Unit Works* * *

* This is a rough summary of how this unit works:*
* *

*The MFJ-259B, and other digitized MFJ antenna analyzers, compare three
major voltages in a 50-ohm bridge circuit. They are:*
* **Vz= Voltage across the load. This voltage is called? Z in the alignment
display menu* * **Vr= Voltage indicating bridge balance. This voltage is
called R in the alignment display menu* * **Vs= Voltage across a 50-ohm
resistor between the RF source and the load. This voltage is called S in the
alignment display menu?/h4> *

*ŒPll voltages are converted through an eight-bit A-D converter to a 256-bit
digitized output with a test-display range of 0-255 bits. By knowing the
ratio of these voltages, as compared to the regulated RF source voltage,
many different load parameters can be calculated. An antenna analyzer could
calculate everything (except sign of reactance) from measuring only Vs and
Vz, but at certain impedances any small error in either Vs and Vz becomes
critical. This is especially true when voltage is digitized into a 256-bit
format (~0.4% steps). At certain impedances, an almost immeasurable? voltage
change will cause a sudden large jump in the measured impedance parameters.*
* *

*To reduce display impedance jumps, SWR is weighed into the calculation of
reactance and resistance at low SWR values. (An SWR bridge is most accurate
when the load is closest to 50 ohms, which is a primary measurement area
where?impedance measurements through Vz and Vs become critical.) By
factoring in a direct SWR measurement from an internal bridge, the analyzer
can check and "correct" any small level errors in Vs or Vz. This reduces the
impedance jump that would occur with a one-bit jump in voltage. This also
why bits must be calibrated for near-perfect accuracy. a one-bit error can
cause a resistive load to appear reactive (the total of Vs and Vz must
always be 255 bits or less for a load to be considered resistive).*
* **Calibrating the MFJ-259B Antenna Analyzer* * *

*This calibration procedure is the correct procedure for later MFJ-259B's.
Disregard any other information. Since MFJ-259B software has been changed
under the same model number, you may find some final performance test steps
not valid. These steps will involve parameters that do not appear on the
display.*
* *

*Be sure you have printed a copy of the board layout showing adjustment
points, have read all this, and have suitable loads before proceeding.?*
* **Adjustments* * *

*This unit has tracking and gain adjustments for Vz, Vs, and Vr. Tracking is
set at low voltages (low bits). Gain is set at high voltages or bits.
Together they make the detector voltage output closely track the actual RF
voltage.?/p> *

*This unit also has meter calibration adjustments. The analog meters almost
certainly suffer from some scale linearity problems, they will be somewhat
less accurate than the digital display. These adjustments only affect analog
meter readings. The meter adjustments do not affect the display.*

*Quiescent current (bias) in the RF amplifier section is adjustable. This
adjustment directly affects output signal harmonic content. Harmonics are
worse with low supply voltages, and with low impedance loads. Be sure you
check the harmonics as outlined below, with a 1/4 wl open-circuit stub!!*

*Excessive harmonics can cause severe errors in measurement of
frequency-selective loads, even when dummy-load SWR tests appear perfect.
Loads most sensitive to harmonic-induced errors include, but are not limited
to, antenna tuners, tank circuits, very short resonant antennas, and
distance to fault and stub length measurements. If you notice something
"funny" going on with a stub measurement, it may be a fault of incorrect
bias.?/p> *
*Warning: Never calibrate around a sudden "problem" that appears. If a
detector suddenly shifts voltage, the problem is almost certainly a
defective detector diode. If the meter is recalibrated with a defective
(leaky) diode, the meter will probably NOT track correctly with frequency.*
* **Alignment * * *

*Tools and Equipment: *
* *

*[?] #2 and #1 Phillips-head screwdrivers*
* *

*[?] Digital meter or accurate analog meter for checking supply voltage*
* *

*[?] Small set of non-metallic alignment wands for coils, or small jeweler's
screwdrivers for controls?/p> *

*[?] Power supply, regulated to 12-volts + - 5%*
* *

*[?] General-coverage receiver with level meter or Spectrum Analyzer (these
are optional with additional work and use of a stub)?/p> *

*[?] ~10 MHz 1/4wl open-stub,?/span>for example 15?good-quality
solid-dielectric RG-8, UHF connector at on end, open on other (not needed
with analyzer or receiver)*

*[?] 2.2-ohm 1/4 or 1/2 watt film resistor (not needed with stub)?*
* *

*[?] Accurate load set to include:*
* *

* A.?? Short*
* *

* B.?? 12.5-W load*
* *

* C.?? 50-W load*
* *

* D.?? 75-W load*
* *

* E.?? 100-W load*
* *

* F.?? 200-W load*
* **Note 1: Loads must be constructed using physically small 1% carbon-film
resistors.? *

   * *
   - * ** DO NOT use large resistors. Acceptable results will be obtained
   when load resistors are mounted in the very bottom of a UHF-male connector.?
   * * ** *
   - * ** The ideal load resistors are surface-mount precision-resistors,
   but other styles will work. It is acceptable to parallel multiple resistors
   to obtain low resistances, but don't series connect more than two
   resistors!? * * ** *
   - * **Never use physically large resistors, such as 1-watt or larger
   resistors, unless you are absolutely positive they are composition-types
   (very rare).? * * ** *
   - * ** Since the loads are used to set the number of bits in critical
   calculations, the maximum reactance error will always be worse than the
   percentage of resistive load error. A one bit error in calibration (~ .4%)
   can shift a resistive load to read reactance. * * *

* **Quick-connect loads can be made with surface mount? resistors on a BNC
male chassis mount connector with the bayonet removed. This makes a �Žuick
connect?connector that will slide directly into a type-N female.?In this
case, use a good UHF to BNC female adaptor for the 259 units. With a 269,
the load will plug directly in to the N female.? * * *

*Note 2: The power source should be the LOWEST expected operating voltage.
DO NOT use a standard "wall-wart" or batteries! You can reduce voltage from
a conventional 13.8v regulated supply by adding a few series diodes. Silicon
diodes will normally drop about 0.6volts or so per diode. Three or four
diodes will reduce place the voltage below 12 volts.*
* *

*WARNING: The MFJ-1315 AC adapter or other "wall-warts" should NOT be used
to power the unit for most alignment steps.?/b>*
* **Step 1* * *

*Visual Inspection: Before, during, and after calibration, be mindful of
physical condition. Watch for missing or loose hardware. Do not tug, stress,
or repeatedly flex leads, or carelessly flop or toss things about. Keep your
bench clean. Follow these rules the entire time you have the unit apart!*
* **Step 2* * *

*Battery Tray Removal: This step provides access to trim-pots and most
inductor adjustments. *
* *

*[?] Remove last two batteries at each end of the tray.*
* *

*[?] Remove two screws (right side) and extract the tray.*
* *

*[?] Always position the battery tray to minimize strain on wires.?/p> *

*Refer to the board layout pictorial for specific control locations.*
* **Step 3* * *

* Band Overlapping: Each band should overlap the next by a small amount to
ensure gap-free coverage from 1.8 MHz to 170 MHz. While viewing the LCD
Frequency Display, wiggle the bandswitch from side-to-side gently. Watch for
any display or meter dropout. Check each band as follows:*
* *

*[?] 114-170 MHz: Oscillator tunes from below 114.0 MHz to above 170.0 MHz.
Check tune for dead spots.*
* *

*[?] 70-114 MHz: Oscillator tunes from below 70.0 MHz to above 114.0 MHz*
* *

*[?] 27-70 MHz: Oscillator tunes from below 27.0 MHz to above 70.0 MHz.*
* *

*[?] 10-27 MHz: Oscillator tunes from below 10.0 MHz to above 27.0 MHz.*
* *

*[?] 4-10 MHz: Oscillator tunes from below 4.0 MHz to above 10.0 MHz.*
* *

*[?] 1.8-4 MHz: Oscillator tunes from below 1.8 MHz to above 4.0 MHz. Check
tune for dead spots.*
* *

*While verifying overlap, check at least the lowest and highest bands
carefully for dead spots. The LCD Display will indicate 000.000MHz if a dead
spot occurs. Dead spots generally indicate a defective tuning capacitor (
TUNE).?/i> *
* *

*If you find the switch causes a dropout the switch may have dry or dirty
contacts, or poor solder joints. Check the solder joints first. If you must
clean and lubricate the switch, be aware it is a difficult task. The entire
board needs to be lifted from the case front. Dirty band-switch contacts may
be restored with spray tuner cleaners. The best place to spray the switch is
from the front side (shaft side), right below the nut. You must remove the
switch indexing tab retainer nut and the metal switch retainer (stop) under
the nut. Be sure the stop goes back exactly as removed. *

*To correct overlap problems, locate and retune the appropriate VFO coil
(see Pictorial for coil locations). Note that L1-L4 are slug-tuned and
require an insulated hex-head tuning wand. If you use the wrong size wand or
a worn wand, it will break a slug!? *

*Inductors L5 and L6 are located on the component side of the board and are
compression-tuned (press turns closer together to lower frequency or spread
apart to raise frequency). Make only very small corrections--especially to
L5 or L6--and recheck the band you are adjusting. You should also check the
next lower band after each adjustment to ensure that the lower band hasn't
moved excessively. *
* **Important Warning: VFO coils MUST be aligned from highest frequency to
lowest frequency. The next higher range affects next lower band the greatest
amount.? Do not attempt VFO coil adjustment unless you are experienced
working with VHF-LC circuitry or complex alignment procedures.?/h4> **Step 4
* * *

*Harmonic Suppression/ Bias: Connect the analyzer exactly as shown
below.?/p> *

   * *
   - *ôÙhe impedance of the cable to the measurement device should match the
   impedance of the measurement device.** *
   - *ôÙhe "T" must be connected either directly to or placed within a few
   inches of the analyzer.** *
   - *ôÙhe power source must be the lowest expected operating voltage.** *
   - *ôÙhe measurement device must be well-shielded, and not pick up any
   substantial signal from the analyzer when the "T" is disconnected from the
   analyzer.*

* *

* *
* **Step 5?/h3> Harmonic Suppression (bias R89): This adjustment reduces
oscillator harmonics. Harmonics will cause incorrect readings under some
load conditions.?  *

*WARNING:? Incorrect adjustment of R89?will NOT show when checking with
resistive dummy loads!!! The unit will appear to calibrate correctly, but
will produce errors in stub length, distance-to-fault, and other frequency
selective functions. * * *
* *

*When R89 is set properly, harmonic suppression of ?0 to ?5dBc should be
possible across most of the analyzer¾É tuning range. This particular
adjustment must be made at the lowest expected operating voltage. Proper
alignment requires a 12.0-volt regulated supply as a power source. NEVER use
an AC adapter or any supply voltage higher than 12-volts when making this
adjustment.?/span>A calibrated spectrum analyzer works best for monitoring
harmonic output, but a well-shielded general-coverage receiver with
signal-level meter will also work.?/span>The receiver MUST be "T'd" into the
analyzer just as the spectrum analyzer is, and the Tee and resistor must be
located at the analyzer connector.†«f you do not have a good-quality receiver
or spectrum?analyzer, use the test mode of the analyzer with a stub. Watch
MFJ analyzer test-mode Vz. Test-mode Vz will roughly indicate total harmonic
voltage when the analyzer is set at the stub's exact resonant frequency.
Entering the test mode is described in Detector Calibration (Step 6).??? *
* *

*[?] a. Install either a 15?RG-8 open stub, or resistor and measurement
device, and tune analyzer to approximately 10 MHz.?/p> *

*[?] b. (stub and internal Vz use only) Observing Vz on the data display
(analyzer test mode), adjust frequency until the lowest fundamental output
reading (or lowest impedance) is obtained. You should clearly see the MFJ
analyzer's fundamental frequency output voltage (Vz) go through a deep
null.?/p> *

*[?] c. Observe the analyzer frequency reading. This is the approximate
resonant frequency of the stub, and the test frequency.?/p> *

*[?] d. Without changing the analyzer test frequency setting, observe the
second harmonic level. This harmonic will be at twice the MFJ analyzer
frequency counter reading..*
* *

*[?] e. Adjust R89 for lowest 2nd harmonic meter reading on the receiver,
lowest Vz test-menu reading, or lowest harmonic level?on the spectrum
analyzer. Be SURE the fundamental frequency level remains nulled in the
analyzer.?/p> *
*WARNING:?Always repeat steps (b) through (e) at least one extra time when
relying on display Vz. The original null point of any stub will shift if
there is a substantial reduction in harmonics after R89 is adjusted. The
original stub frequency, as observed at (c), will probably change slightly.
It is NOT necessary to recheck when doing a resistor load test with a
good-quality spectrum analyzer or receiver. With a resistor, exact test
frequency is NOT critical.* * **NOTE: If you have a poorly performing
spectrum analyzer or receiver with limited dynamic range, use a stub with
the spectrum analyzer or receiver instead of a 2.2 ohm resistor. If you have
a reasonable quality spectrum analyzer or receiver (at least 50dB dynamic
range) use a 2.2-ohm non-inductive resistor in lieu of the stub, resistor
adjustment is easier and more accurate.* * **Detector Calibration * * **Step
6:?/h3> *

*This critical sequence calibrates A-D conversion for various load
conditions. If you know your unit has been tampered with, preset trim pots
R88, R89, and R90 to their center positions before continuing. If you find
any control bottoms-out in adjustment, you almost certainly have installed
an incorrect load or the analyzer has a defective detector diode.?*
* *

*To prepare for detector tracking alignment, place the analyzer in Test
Mode. Entering test mode may be tricky with some units, and it may take
practice. To enter Test Mode: *
* *

*[?] Turn power off. *
* *

*[?] Hold down MODE and GATE?/i> buttons while restoring power.*
* *

*[?] As display comes up, slowly (about 1 second period) rock between
pushing the MODE and GATE switches alternately (the best method is to use
two fingers, and rock your hand from side to side between the two buttons)*
* *

*[?] Confirm analyzer has entered test mode (it may take more than one try).
*
* *

*[?] Using the MODE button, advance display to the R-S-Z screen (shown
below).*
* **Note: If you go past the R-S-Z screen, you can still see R-S-Z by
pushing and holding the MODE button.* * *

*?o:p> *
* *

*    10.000 MHz *
* **???????????????????????? Rxxx???Sxxx??/span> ?Zxxx* * *

*  ?o:p> ?
[?] Tune analyzer operating frequency to approximately 10.000 MHz *
* *

*[?] Leave antenna connector Open*
* *

*[?] Set R72 for Z=255*
* *

*[?] Install the Short*
* *

*[?] Set R73 for S=255*
* *

*[?] Install 12.5-W load*
* *

*[?] Set R90 for Z=051*
* *

*[?] Set R53 for R=153*
* *

*[?] Install 200-W load*
* *

*[?] Set R88 for S=051*
* *

*[?] Set R72 for Z=204*
* *

*[?] Install 75-W load*
* *

*[?] Set R89 for R=051 *
* *

*[?] Install 12.5-W load*
* *

*[?] Reset R90 for Z=051*
* *

*[?] Set R73 for S=204*
* *

*[?] Reset R53 for R=153*
* *

*[?] Install 200-W load*
* *

*[?] Reset R88 for S=051*
* *

*[?] Verify or set Z=204*
* *

*[?] Install 75-W load*
* *

*[?] Reset R89 for R=051 *
* **Important Note:  Small single-turn trimpots are touchy to adjust and
tracking settings are somewhat interactive. If specified readings aren¼±
obtained on the run-through, repeat the sequence a second time (accuracy
counts). When the sequence is complete, turn power off to remove the
analyzer from Test Mode.* * **Be particularly mindful of the total bits of
Vz and Vs. If the sum of these bits ever exceeds 255 with a resistive load,
the analyzer will indicate reactance.?* * *

*Display Test and Analog Meter Calibration *
* **Step 7:* * *

*This step sequence checks meter calibration and verifies accuracy of the
LCD Display information. *
* *

*Remove and re-apply power and enter the Real-Imaginary impedance mode R-X.
Readings + or - 10% of reading or?+ or - 5 ohms of display, whichever is
larger, are considered within design specifications. Typically digital
readings are almost perfect with proper detector calibration. Analog meter
readings may be outside that range, and as much as 20% off with some load
values.?*
* *

*[?] Install 75-W load*
* *

*[?] Verify reading of R= 75 X=0 on LCD Display (?/span>10%)*
* *

*[?] Install 50-W load*
* *

*[?] Verify reading of R=50 X=0 on LCD Display (?/span>10%)*
* *

*[?] Set R67 for reading of 50 on the Impedance Meter.*
* *

*[?] Verify reading of 1.0 SWR Meter (no deflection).*
* *

*[?] Install Open load*
* *

*[?] Verify reading above 400 on Impedance Meter *
* *

*[?] Install 100-W load*
* *

*[?] Verify reading of R=100 X=0 on LCD Display (?/span>10%)*
* *

*[?] Verify reading of 100 on Impedance meter (approximate).?/span>*
* *

*[?] Set R56 for a reading of 2 (2:1) on the SWR Meter*
* *

*[?] Install 12.5-W load*
* *

*[?] Verify a reading of 4:1 SWR on LCD display (3.8-4.2 good)?/span>*
* *

*[?] Verify reading of >3 (greater than 3:1) on SWR Meter*
* *

*[?] Install 200-W load*
* *

*[?] Verify reading of 4:1 SWR on LCD display (3.8-4.2 good)*
* *

*[?] Verify reading of >3 (greater than 3:1) on SWR Meter *
* *

*?o:p> *
* **Capacitance Mode Check * * **Step 8:?/b> ?/o:p>* * *

*If you have a few precision capacitors, you can verify the calibration
between the ranges of 100 and 5000 pF. Read the analyzer manual for details
of capacitor measurement.??*
* *

*[?] Install no load*
* *

*[?] Set Mode to Capacitance *
* *

*[?] Set VFO to 70 MHz*
* *

*[?] Verify 4-6 pF reading on LCD Display*
* *

*?o:p>Frequency Counter Check  *
* **Step 9:* * *

*These steps verify accuracy of the counter. Note that the counter¾É clock
isn¼± user-accessible, so no adjustments will be made. To conduct this test,
use a general-coverage receiver in AM mode.*
* *

*?o:p> *
* *

*[?] Tune in WWV on 5.0,10.0,15.0, or 20.0 MHz (frequency with best
reception).*
* *

*[?] Install a short clip lead or wire in the analyzer¾É Antenna jack.*
* *

*[?] Turn on the analyzer and zero-beat the WWV signal as closely as
possible.*
* *

*[?] Compare LCD Display reading to the WWV frequency being used.*
* *

*[?] Verify agreement is within ?/span>5 kHz. *
* **Advanced Modes Check  * * **Step 10:?o:p> * * *

*This sequence verifies operation of the analyzer¾É advanced features. To
enter Advanced Mode menu:*
* *

*[?] Turn unit off.*
* *

*[?] Hold down the MODE and GATE switches while turning power on.*
* *

*[?] Verify ?i style="">Advanced?/i> appears on the LCD Display.*
* *

*[?] Install Open load *
* *

*[?] Tune VFO to >170 MHz (top end of coverage range)*
* *

*[?] Verify Z = <650 W with (about) 90?/span> phase shift*
* *

*[?] Install RG-8 open stub*
* *

*[?] Tune VFO for minimum Z reading (around 10 MHz)*
* *

*[?] Verify Z-min = 0 to 2 W*
* *

*[?] Install 50-W load*
* *

*[?] Set VFO to 1.8 MHz ?/span>*
* *

*[?] Verify Z = 50 W, q = 0?/span>, and SWR = 1 (?/span>10%)*
* *

*[?] Enter RL Mode (return loss)*
* *

*[?] Verify RL = >42 dB, r = 0, SWR = 1 *
* *

*[?] Enter Match Efficiency Mode (skipping DTF Mode) *
*

[?] Verify ME @ 100%?(approximate)

[?] Press and hold MODE and GATE buttons to restore Main Modes

[?] Remove load and verify Z = >650 on LCD Display

Conclusion:

Step 11:

[?] Reinstall battery tray

[?] Confirm charger jumper is set for type of batteries used (disable for
alkaline).

[?] Reinstall cover

ôÙhis completes calibration.

?o:p>

?o:p>

?o:p>

?o:p>

?o:p>

?o:p>

?o:p>

?o:p>

?o:p>

?o:p>
 MFJ-259B Calibration Checklist

Make a Xerox copy and check each box as you proceed down the calibration
list.

?/span>
 Physical Condition

[?] Hardware, batteries okay

?o:p>

Harmonic Check

[?] Suppression -35 dBc or better

?o:p>
 Overlapping

[?] All bands have sufficient overlap

?o:p>
 Binary Cal: 10 MHz

[? ] Open

[?] R72 for Z=255

[?] Short

[?] R73 for S=255

[?] 12.5-W

[?] R90 for Z=051

[?] R53 for R=153

[?] 200-W

[?] R88 for S=051

[?] R72 for Z=204

[?] 75-W

[?] R89 for R=051

[?] 12.5-W

[?] R90 for Z=051

[?] R73 for S=204

[?] R53 for R=153

[?] 200-W

[?] R88 for S=051

[?] Verify Z=204

[?] 75-W

[?] R89 for R=051

?o:p>
 Analog Cal: 10 MHz, values ?/span>10%

[?] 75-W

[?] Verify R= 75 X=0

[?] 50-W

[?] Verify R=50 X=0

[?] Set R67 for 50 on Imp Meter.

[?] Verify 1.0 on SWR Meter

[?] Open

[?] Verify >400 on Imp Meter

[?] 100-W

[?] Verify R=100 X=0

[?] Verify 100 on Imp Meter?/span>

[?] R56 for 2 (2:1) on SWR Meter

[?] 12.5-W

[?] Verify 4:1 on LCD (3.8-4.2)?/span>

[?] Verify >3 on SWR Meter

[?] 200-W

[?] Verify 4:1 on LCD (3.8-4.2)

[?] Verify >3 on SWR Meter

?o:p>
 Capacitance Mode Check

[?] Open

[?] Set VFO to 70 MHz

[?] Set Mode to Capacitance

[?] Verify C  4-pF

?o:p>

Counter Check

[?] Counter Okay

?o:p>
 Advanced Modes

[?] Tune to 170 MHz

[?] Open

[?] Verify <650, Phase @ 90?/span>

[?] 3? RG-58

[?] Tune for Z-min (@150 MHz)

[?] Verify Z= 0-2 W

[?] 50-W

[?] Tune to 1.8 MHz ?/span>

?o:p>

[?] Verify Z=50 W, q=0?/span>, SWR=1

[?] Advance to Return Loss

[?] Verify RL=>42dB, r=0, SWR=1

[?] Advance to Match Efficiency

[?] Verify ME @ 100%

[?] Restore Main Modes

[?] Open

[?] Verify Z=>650

?o:p>
 End of Procedure

?o:p> ?


   Pictorial Diagram of Analyzer Board

Locations for trimpots and inductors




?o:p>

?o:p>

?o:p>
 ?o:p>
 **Loads Using Standard-Value Resistors* * *

*?o:p> *
*



   ?/p>

?/p>

?/p>

?/p>

   - Install resistors all the way down in the connector, the goal is zero
   lead length

 .

   - Use precision 1% carbon or metal film 1/8th-1/4 watt resistors

 ?o:p> ?

12.5W = (4) 50-ohm or 15W and 82W in parallel

??????????????????50W = 49.9-ohm?or 100W and 100W in parallel
 *

*??????????????????75W = 75-ohm or 150W and 150W in parallel*

*??????????????????100W = 100W*

*??????????????????200W = 200-ohm or 100W + 100W in series*
* *

*?/span>Important Note: These simple HF loads will not be accurate for SWR
checks above 30 MHz. Only precision terminations should be used in the VHF
region, and even then there can be some errors. The MFJ-259B does not
correct for connector impedance bumps or the electrical length between an
external load and the bridge inside the unit. *
* *

*Welcome  to W8JI.com!*
[ Home <http://www.w8ji.com/> ]


 * *

(c)2003-2004 W8JI

Revised 8/24/03

Revised May18 2005 R84 named in error R89 in harmonic adjustment

Warning!

MFJ manuals were re-written and distance-to-fault measurement procedure
errors were introduced. I think this occurred sometime around 2002. If your
manual tells you to tune to the *next band up or down* when measuring any
length process (stubs, DTF, etc.) it is absolutely incorrect. The correct
procedure is to tune for lowest Z on the meter and lowest X on the digital
display, set the reading as "1", and then locate the very next dip UP or
DOWN in frequency and store it in "2".  You can use up or down, it just has
to be the very next dip where meter Z is lowest and X on the digital display
is as low as possible. I'm not sure what other errors may have been
introduced in the manual rewrite.

History:

*I worked with another contract engineer (my friend JB) in designing the MFJ
259 and 269. No one else outside of MFJ was involved, and certainly no one
named Ted Hart.  *

*This information is here because it is the correct way to calibrate the
MFJ-259B analyzer. This work is all donated. K1BQT took an instruction set
supplied by MFJ and re-wrote it. I modified, expanded and edited that work.
This page is the result.*

*It is best that no one copy this, and start handing it out in mass. The
only reason for this request is there must be a point of control of
information, so it can be corrected or expanded as errors or omissions are
found.*

*I am not aware of any other source that gives correct calibration
procedures. It is important that the 259 be calibrated by these steps, even
if they sound complex. If you don't do it right, don't do it. Without
following these steps, many special functions may not work correctly even if
the unit tests properly on calibration loads!*
 How This Type of Device Works

This type of analyzer contains an RF oscillator, a linear amplifier to
increase power, and an internal resistor bridge in a conventional Whetstone
bridge configuration.



Since it is designed to be inexpensive, there are a few shortfalls with this
system.

The bridge is dc-coupled from an internal resistor bridge to the antenna
port. The bridge detectors are NOT frequency selective, and respond to
anything from minor dc offsets through microwave signals. This causes a
potential problem if there is * any* voltage appearing across the antenna
port, from dc through microwave. (This is also true for competing analyzers
from other manufacturers.) There are multiple reasons why, at the time of
design, these units were dc coupled with broadband detectors. Hopefully
someday a higher cost-design with selective detectors will become available,
but for right now this is all that is available for amateur use from any
manufacturer.

The second shortfall is the internal amplifier must be linear and have very
low total harmonic content. Total harmonic power, at the lowest load
impedance, must be down at least 25dB and preferably 35dB. This is true for
*ANY* antenna analyzer, since you do not want the analyzer to measure the
load at two frequencies!

* Because the detector is broadband and because it is dc coupled to the
antenna, any external voltage across the input port causes measurement
errors. *It is the *accumulated voltage of multiple sources *that is most
important, not the strength of any individual signal. Because of that, large
antennas should be tested at times when propagated signals in the range of
the antenna's response are at minimum strength.

A definite RFI improvement occurs with a bandpass filter, but
multiple-section bandpass filters cause impedance measurement problems.
Multiple-section filters behave like transmission lines of random line
impedances, loss, and lengths as frequency is varied. The best solution is
to use a single-stage bandpass filter and dc isolation on large arrays or
with long feedlines. I often use a good 1:1 isolation transformer for
measurements, and often find a parallel L/C filter (like the MFJ-731 Filter)
useful.
  Most Likely Failures

Other than manufacturing errors, the * detector diodes clearly stand out as
the most common problem. They are the most easily damaged devices in the
analyzer.* If you have a sudden problem, it is most likely a defective
detector diode. Diode damage almost always comes from accidentally applying
voltage on the antenna port.

Why are the diodes so sensitive? In order for the detectors to be accurate
within a fraction of a percent (one bit), detector diodes must have very low
capacitance and a very low threshold voltage. This means the diodes, through
necessity, must be low-power zero-bias Schottky microwave detector diodes.
The same characteristics that make them accurate and linear cause the diodes
to be especially sensitive to damage from small voltage spikes. * ALWAYS
discharge large antennas before connecting them to the analyzer! Never apply
external voltages greater than 3 volts to the antenna port!*
 Technical Support Error

>From time to time MFJ gives incorrect advice on the 259B and other
analyzers. One bad piece of advice that has come to my attention concerns
measuring stubs. Someone in MFJ support has been telling customers that the
older or original manual is wrong and to tune for a dip on the next range,
but unfortunately they are wrong. The older manual is actually correct!
Whatever anyone might tell you to do when calling MFJ technical support,
*this* is how it has to be done:

   - You MUST tune for lowest X and minimum impedance.
   - Store that frequency point.
   - Move to the VERY NEXT minimum X and lowest impedance either up or down
   in frequency.
   - When you store that point, the correct length will appear. This assumes
   you set the velocity at 1.00 to obtain electrical length

 *Note:* Measurements of stubs and cable lengths will occur if the harmonic
null is not adjusted correctly in the 259 or 269!
 How This Unit Works

This is a rough outline of how this unit works:

The MFJ-259B, and other digitized MFJ antenna analyzers, compare three major
voltages in a 50-ohm bridge circuit. They are:
 Vz= Voltage across the load. This voltage is called  Z in the alignment
display menu Vr= Voltage indicating bridge balance. This voltage is called R
in the alignment display menu Vs= Voltage across a 50-ohm resistor between
the RF source and the load. This voltage is called S in the alignment
display menu

 All voltages are converted through an eight-bit A-D converter to a 256-bit
digitized output with a test-display range of 0-255 bits. By knowing the
ratio of these voltages, as compared to the regulated RF source voltage,
many different load parameters can be calculated. An antenna analyzer could
calculate everything (except sign of reactance) from measuring only Vs and
Vz, but at certain impedances any small error in either Vs and Vz becomes
critical. This is especially true when voltage is digitized into a 256-bit
format (~0.4% steps). At certain impedances, an almost immeasurable  voltage
change will cause a sudden large jump in the measured impedance parameters.

To reduce display impedance jumps, SWR is weighed into the calculation of
reactance and resistance at low SWR values. (An SWR bridge is most accurate
when the load is closest to 50 ohms, which is a primary measurement area
where  impedance measurements through Vz and Vs become critical.) By
factoring in a direct SWR measurement from an internal bridge, the analyzer
can check and "correct" any small level errors in Vs or Vz. This reduces the
impedance jump that would occur with a one-bit jump in voltage. This also
why bits must be calibrated for near-perfect accuracy. a one-bit error can
cause a resistive load to appear reactive (the total of Vs and Vz must
always be 255 bits or less for a load to be considered resistive).
 Calibrating the MFJ-259B Antenna Analyzer

This calibration procedure is the correct procedure for later MFJ-259B's.
Disregard any other information. Since MFJ-259B firmware has several
versions under the same model number, you may find some final performance
verification steps not valid. These steps will involve parameters that do
not appear on the display.

Be sure you have printed a copy of the board layout showing adjustment
points, have read all this, and have suitable loads before proceeding.
 Adjustments

This unit has tracking and gain adjustments for Vz, Vs, and Vr. Tracking is
set at low voltages (low bits). Gain is set at high voltages or bits.
Together they make the detector voltage output closely track the actual RF
voltage.

This unit also has meter calibration adjustments. The analog meters almost
certainly suffer from some scale linearity problems, they will be somewhat
less accurate than the digital display. These adjustments only affect analog
meter readings. The meter adjustments do not affect the display.

Quiescent current (bias) in the RF amplifier section is adjustable. This
adjustment directly affects output signal harmonic content. Harmonics are
worse with low supply voltages, and with low impedance loads. *Be sure you
check the harmonics as outlined below, with a 1/4 wl open-circuit stub!!*

Excessive harmonics can cause severe errors in measurement of
frequency-selective loads, even when dummy-load SWR tests appear perfect.
Loads most sensitive to harmonic-induced errors include, but are not limited
to, antenna tuners, tank circuits, very short resonant antennas, and
distance to fault and stub length measurements. If you notice something
"funny" going on with a stub measurement, it may be a fault of incorrect
bias.
 Warning: Never calibrate around a sudden "problem" that appears. If a
detector suddenly shifts voltage, the problem is almost certainly a
defective detector diode. If the meter is recalibrated with a defective
(leaky) diode, the meter will probably NOT track correctly with
frequency. Alignment


*Tools and Equipment: *

[  ] #2 and #1 Phillips-head screwdrivers

[  ] Digital meter or accurate analog meter for checking supply voltage

[  ] Small set of non-metallic alignment wands for coils, or small jeweler's
screwdrivers for controls

[  ] Power supply, regulated to 12-volts + - 5%

[  ] General-coverage receiver with level meter or Spectrum Analyzer (these
are optional with additional work and use of a stub)

[  ] ~10 MHz 1/4wl open-stub, for example 15' good-quality solid-dielectric
RG-8, UHF connector at on end, open on other (not needed with analyzer or
receiver)

[  ] 2.2-ohm 1/4 or 1/2 watt film resistor (not needed with stub)

[  ] Accurate load set to include:

 A.     Short

 B.     12.5-W* *load

 C.    50-W load

 D.    75-W load

 E.     100-W load

 F.     200-W load
 Note 1: Loads must be constructed using physically small 1% carbon-film
resistors.

   - DO NOT use large resistors. Acceptable results will be obtained when
   load resistors are mounted in the very bottom of a UHF-male connector.
   - The ideal load resistors are surface-mount precision-resistors, but
   other styles will work. It is acceptable to parallel multiple resistors to
   obtain low resistances, but don't series connect more than two resistors!
   - Never use physically large resistors, such as 1-watt or larger
   resistors, unless you are absolutely positive they are composition-types
   (very rare).
   - Since the loads are used to set the number of bits in critical
   calculations, the maximum reactance error will always be worse than the
   percentage of resistive load error. *A one bit error in calibration (~
   .4%) can cause a purely resistive load to read reactive.*

 Quick-connect loads can be made with surface mount  resistors on a BNC male
chassis mount connector with the bayonet removed. This makes a "quick
connect" connector that will slide directly into a type-N female.  In this
case, use a good UHF to BNC female adaptor for the 259 units. With a 269,
the load will plug directly in to the N female.

*Note 2: The power source should be the LOWEST expected operating voltage.
DO NOT use a standard "wall-wart" or batteries! You can reduce voltage from
a conventional 13.8v regulated supply by adding a few series diodes. Silicon
diodes will normally drop about 0.6volts or so per diode. Three or four
diodes will reduce place the voltage below 12 volts.*

*WARNING: *The MFJ-1315 AC adapter or other "wall-warts" should NOT be used
to power the unit for most alignment steps.* *
 *Step 1*

*Visual Inspection:* Before, during, and after calibration, be mindful of
physical condition.* *Watch for missing or loose hardware. Do not tug,
stress, or repeatedly flex leads, or carelessly flop or toss things about.
Keep your bench clean. Follow these rules the entire time you have the unit
apart!
 Step 2

*Battery Tray Removal: *This step provides access to trim-pots and most
inductor adjustments.* *

[  ] Remove last two batteries at each end of the tray.

[  ] Remove two screws (right side) and extract the tray.

[  ] Always position the battery tray to minimize strain on wires.

Refer to the board layout pictorial for specific control locations.
 Step 3

*Band Overlapping: *Each band should overlap the next by a small amount to
ensure gap-free coverage from 1.8 MHz to 170 MHz. While viewing the *LCD
Frequency Display*, wiggle the bandswitch from side-to-side gently. Watch
for any display or meter dropout. Check each band as follows:

[  ] *114-170 MHz:* Oscillator tunes from below 114.0 MHz to above 170.0
MHz. Check tune for dead spots.

[  ] *70-114 MHz:* Oscillator tunes from below 70.0 MHz to above 114.0 MHz

[  ] *27-70 MHz:* Oscillator tunes from below 27.0 MHz to above 70.0 MHz.

[  ] *10-27 MHz:* Oscillator tunes from below 10.0 MHz to above 27.0 MHz.

[  ] *4-10 MHz:* Oscillator tunes from below 4.0 MHz to above 10.0 MHz.

[  ] *1.8-4 MHz:* Oscillator tunes from below 1.8 MHz to above 4.0 MHz.
Check tune for dead spots.

*While verifying overlap, at least check the lowest and highest bands
carefully for dead spots. The LCD Display will indicate 000.000MHz if a dead
spot occurs. Dead spots generally indicate a defective tuning capacitor (
TUNE). *

*If you find wiggling the switch causes a dropout, the switch may have dry
or dirty contacts. Less likely are poor solder joints, but check solder
joints first. If you must clean and lubricate the switch, be aware it is a
difficult task. The entire board needs to be lifted from the case front.
Dirty band-switch contacts may be restored with spray tuner cleaners. The
best place to spray the switch is from the front side (shaft side), right
below the nut. You must remove the switch indexing tab retainer nut and the
metal switch retainer (stop) under the nut. Be sure the stop goes back
exactly as removed.*

To correct overlap problems, locate and retune the appropriate VFO coil (see
Pictorial for coil locations). Note that L1-L4 are slug-tuned and require an
insulated hex-head tuning wand. If you use the wrong size wand or a worn
wand, it will break a slug!

Inductors L5 and L6 are located on the component side of the board and are
compression-tuned (press turns closer together to lower frequency or spread
apart to raise frequency). Make only very small corrections--*especially to
L5 or L6*--and recheck the band you are adjusting. You should also check the
*next lower band* after each adjustment to ensure that the lower band hasn't
moved excessively.
 *Important Warning:* VFO coils MUST be aligned from highest frequency to
lowest frequency. The next higher range affects next lower band the greatest
amount.  Do not attempt VFO coil adjustment unless you are experienced
working with VHF-LC circuitry or complex alignment procedures.  Step 4

*Harmonic Suppression/ Bias: *Connect the analyzer * exactly *as shown
below.

   -  The impedance of the cable to the measurement device should match the
   impedance of the measurement device.
   -  The "T" must be connected either directly to or placed within a few
   inches of the analyzer.
   -  The power source must be the lowest expected operating voltage.
   -  The measurement device must be well-shielded, and not pick up any
   substantial signal from the analyzer when the "T" is disconnected from the
   analyzer.

   Step 5  *Harmonic Suppression (**bias **R8**4**):* This adjustment
reduces oscillator harmonics. Harmonics will cause incorrect readings under
some load conditions.

* WARNING:*  * Incorrect adjustment of R84  will NOT show when checking with
resistive dummy loads!!! The unit will appear to calibrate correctly, but
will produce errors in stub length, distance-to-fault, and other frequency
selective functions. *

When R84 is set properly, harmonic suppression of ¨C30 to ¨C35dBc should be
possible across most of the analyzer's tuning range. This particular
adjustment must be made at the lowest expected operating voltage. Proper
alignment requires a 12.0-volt regulated supply as a power source. NEVER use
an AC adapter or any supply voltage higher than 12-volts when making this
adjustment. A calibrated spectrum analyzer works best for monitoring
harmonic output, but a well-shielded general-coverage receiver with
signal-level meter will also work. The receiver MUST be "T'd" into the
analyzer just as the spectrum analyzer is, and the Tee and resistor must be
located at the analyzer connector. If you do not have a good-quality
receiver or spectrum  analyzer, use the test mode of the analyzer with a
stub. Watch MFJ analyzer test-mode Vz. Test-mode Vz will roughly indicate
total harmonic voltage when the analyzer is set at the stub's exact resonant
frequency. Entering the test mode is described in Detector Calibration (Step
6).

[  ]* a.* Install either a 15' RG-8 open stub, or resistor and measurement
device, and tune analyzer to approximately *10 MHz*.

[  ] *b.* *(stub and internal Vz use only)* Observing Vz on the data display
(analyzer test mode), adjust frequency until the *lowest *fundamental output
reading (or lowest impedance) is obtained. You should clearly see the MFJ
analyzer's fundamental frequency output voltage (Vz) go through a deep
null.

[  ] *c.* Observe the analyzer frequency reading. This is the approximate
resonant frequency of the stub, and the *test frequency*.

[  ] *d.* Without changing the analyzer * test frequency* setting, observe
the second harmonic level. This harmonic will be at twice the MFJ analyzer
frequency counter reading*.*.

[  ] *e.* Adjust *R84* for *lowest 2nd harmonic meter reading *on the
receiver, lowest Vz test-menu reading, or lowest harmonic level  on the
spectrum analyzer. Be SURE the fundamental frequency level remains nulled in
the analyzer.
 WARNING:  Always repeat steps (b) through (e) at least one extra time when
relying on display Vz. The original null point of any stub will shift if
there is a substantial reduction in harmonics after R84 is adjusted. The
original stub frequency, as observed at (c), will probably change slightly.
It is NOT necessary to recheck when doing a resistor load test with a
good-quality spectrum analyzer or receiver. With a resistor, exact test
frequency is NOT critical. NOTE: If you have a poorly performing spectrum
analyzer or receiver with limited dynamic range, use a stub with the
spectrum analyzer or receiver instead of a 2.2 ohm resistor. If you have a
reasonable quality spectrum analyzer or receiver (at least 50dB dynamic
range) use a 2.2-ohm non-inductive resistor in lieu of the stub, resistor
adjustment is easier and more accurate. Detector Calibration  Step 6:

This critical sequence calibrates A-D conversion for various load
conditions. If you know your unit has been tampered with, preset trim pots *
R88*, *R89*, and * R90* to their center positions before continuing. If you
find any control bottoms-out in adjustment, you almost certainly have
installed an incorrect load or the analyzer has a defective detector
diode.

To prepare for detector tracking alignment, place the analyzer in *Test
Mode. *Entering test mode may be tricky with some units, and it may take
practice. To enter *Test Mode*:

[  ] Turn power off.

[  ] Hold down *MODE *and* GATE  *buttons while restoring power.

[  ] As display comes up, slowly (about 1 second period) rock between
pushing the *MODE *and * GATE* switches alternately (the best method is to
use two fingers, and rock your hand from side to side between the two
buttons)

[  ] Confirm analyzer has entered test mode (it may take more than one try).

[  ] Using the *MODE* button, advance display to the *R-S-Z* screen (shown
below).
 Note: If you go past the R-S-Z screen, you can still see R-S-Z by pushing
and holding the *MODE* button.



   *10.000 MHz *
                                                Rxxx      Sxxx      Zxxx


[  ] Tune analyzer operating frequency to approximately *10.000 MHz*

[  ] Leave antenna connector *Open*

[  ] Set *R72* for *Z=255*

[  ] Install the *Short*

[  ] Set *R73* for *S=255*

[  ] Install *12.5-W *load

[  ] Set *R90* for *Z=051*

[  ] Set *R53* for *R=153*

[  ] Install *200-W *load

[  ] Set *R88* for *S=051*

[  ] Set *R72* for *Z=204*

[  ] Install *75-W *load

[  ] Set *R89* for *R=051 *

[  ] Install *12.5-W *load

[  ] Reset *R90* for *Z=051*

[  ] Set *R73* for *S=204*

[  ] Reset *R53* for *R=153*

[  ] Install *200-W *load

[  ] Reset *R88* for *S=051*

[  ] Verify or set *Z=204*

[  ] Install *75-W* load

[  ] Reset *R89* for *R=051 *
 *Important Note: *Small single-turn trimpots are touchy to adjust and
tracking settings are somewhat interactive. If specified readings aren't
obtained on the run-through, repeat the sequence a second time (accuracy
counts). When the sequence is complete, turn power off to remove the
analyzer from *Test Mode*. Be particularly mindful of the total bits of Vz
and Vs. If the sum of these bits ever exceeds 255 with a resistive load, the
analyzer will indicate reactance.

Display Test and Analog Meter Calibration
Step 7:

This step sequence checks meter calibration and verifies accuracy of the *LCD
Display* information.* *

Remove and re-apply power and enter the *Real-Imaginary* impedance mode *R-X
*. Readings + or - 10% of reading or  + or - 5 ohms of display, whichever is
larger, are considered within design specifications. Typically digital
readings are almost perfect with proper detector calibration. Analog meter
readings may be outside that range, and as much as 20% off with some load
values.

[  ] Install *75-W* load

[  ] Verify reading of *R= 75 X=0* on * LCD Display* (¡À10%)

[  ] Install *50-W* load

[  ] Verify reading of *R=50* *X=0* on* LCD Display *(¡À10%)

[  ] Set *R67* for reading of *50 *on the *Impedance Meter*.

[  ] Verify reading of *1.0 **SWR Meter* (no deflection).

[  ] Install *Open *load

[  ] Verify reading above *400 *on* * *Impedance Meter*

[  ] Install *100-W* load

[  ] Verify reading of *R=100* *X=0* on *LCD Display *(¡À10%)

[  ] Verify reading of *100 *on * Impedance meter *(approximate).

[  ] Set *R56* for a reading of *2* (2:1) on the *SWR Meter*

[  ] Install *12.5-W* load

[  ] Verify a reading of *4:1* SWR on * LCD* *display* (3.8-4.2 good)

[  ] Verify reading of *>3* (greater than 3:1) on *SWR Meter*

[  ] Install *200-W* load

[  ] Verify reading of *4:1* SWR on *LCD display* (3.8-4.2 good)

[  ] Verify reading of *>3* (greater than 3:1) on *SWR Meter *


 Capacitance Mode Check  *Step 8:   *

If you have a few precision capacitors, you can verify the calibration
between the ranges of 100 and 5000 pF. Read the analyzer manual for details
of capacitor measurement.

[  ] Install no load

[  ] Set *Mode** *to *Capacitance *

[  ] Set VFO to *70 MHz*

[  ] Verify *4-6 pF* reading on LCD Display

 Frequency Counter Check
*Step 9:*

These steps verify accuracy of the counter. Note that the counter's clock
isn't user-accessible, so no adjustments will be made. To conduct this test,
use a general-coverage receiver in AM mode.



[  ] Tune in *WWV* on 5.0,10.0,15.0, or 20.0 MHz (frequency with best
reception).

[  ] Install a short clip lead or wire in the analyzer's *Antenna* jack.

[  ] Turn on the analyzer and *zero-beat the WWV signal* as closely as
possible.

[  ] Compare *LCD Display* reading to the WWV frequency being used.

[  ] Verify agreement is within * ¡À5 kHz. *
 Advanced Modes Check  *Step 10:  *

This sequence verifies operation of the analyzer's advanced features. To
enter *Advanced Mode* menu:

[  ] Turn unit off.

[  ] Hold down the MODE and GATE switches while turning power on.

[  ] Verify "*Advanced"* appears on the * LCD Display*.

[  ] Install *Open* load* *

[  ] Tune VFO to *>170 MHz* (top end of coverage range)

[  ] Verify *Z* = * <650 W* with (about) *90¡ã* phase shift

[  ] Install RG-8 open stub

[  ] Tune VFO for minimum *Z* reading (around 10 MHz)

[  ] Verify *Z-min = 0* to * 2 W*

[  ] Install * 50-W* load

[  ] Set VFO to *1.8 MHz* * *

[  ] Verify *Z = 50 W*, *q = 0¡ã*, and *SWR = 1* (¡À10%)

[  ] Enter *RL* *Mode* (return loss)

[  ] Verify *RL = *>*42 dB*, *r = 0*, *SWR = 1 *

[  ] Enter *Match Efficiency Mode* (skipping *DTF Mode*)* *

[  ] Verify * ME @ 100%*  (approximate)

[  ] Press and hold MODE and GATE* * buttons* *to restore *Main Modes*

[  ] Remove load and verify *Z = >650* on *LCD Display *

*Conclusion: *

*Step 11:*

[  ] Reinstall battery tray

[  ] Confirm charger jumper is set for type of batteries used (disable for
alkaline).

[  ] Reinstall cover

 This completes calibration.


 MFJ-259B Calibration Checklist

Make a copy and check each box as you proceed down the calibration list.


 Physical Condition

[  ] Hardware, batteries okay

*  *

*Harmonic Check *

[  ] Suppression -35 dBc or better


 Overlapping

[  ] All bands have sufficient overlap


 Check Digital Calibration at 10 MHz in test mode.

*[*  ] *Open*

[  ] R72 for Z=255

[  ] *Short*

[  ] R73 for S=255

[  ] *12.5-W*

[  ] R90 for Z=051

[  ] R53 for R=153

[  ] *200-W*

[  ] R88 for S=051

[  ] R72 for Z=204

[  ] *75-W *

[  ] R89 for R=051

[  ] *12.5-W*

[  ] R90 for Z=051

[  ] R73 for S=204

[  ] R53 for R=153

[  ] *200-W*

[  ] R88 for S=051

[  ] Verify Z=204

[  ] *75-W*

[  ] R89 for R=051


 Analog Calibration: 10 MHz, values approximate [  ] *75-W*

[  ] Verify R= 75 X=0

[  ] *50-W*

[  ] Verify R=50 X=0

[  ] Set R67 for 50* *on Imp Meter.

[  ] Verify 1.0 on SWR Meter

[  ] *Open *

[  ] Verify >400 on* *Imp Meter

[  ] *100-W*

[  ] Verify *R=100* * X=0*

[  ] Verify 100* *on Imp Meter

[  ] R56 for 2 (2:1) on SWR Meter

[  ] *12.5-W*

[  ] Verify 4:1 on LCD (3.8-4.2)

[  ] Verify >3 on SWR Meter

[  ] *200-W*

[  ] Verify 4:1 on LCD (3.8-4.2)

[  ] Verify >3 on SWR Meter* *


 Capacitance Mode Check

[  ] *Open*

[  ] Set VFO to 70 MHz

[  ] Set Mode to *Capacitance *

[  ] Verify C  4-pF

**

*Counter Check *

[  ] Counter Okay


 * Advanced Modes *

[  ] Tune to 170 MHz

[  ] *Open*

[  ] Verify <650, Phase @ 90¡ã

[  ] *3' RG-58*

[  ] Tune for Z-min (@150 MHz)

[  ] Verify Z= 0-2 W

[  ] * 50-W*

[  ] Tune to 1.8 MHz * *



[  ] Verify Z=50 W, q=0¡ã, SWR=1

[  ] Advance to Return Loss

[  ] Verify RL=>42dB, r=0, SWR=1* *

[  ] Advance to Match Efficiency* *

[  ] Verify ME @ 100%

[  ] Restore Main Modes

[  ] *Open*

[  ] Verify Z=>650* *

*  *
 End of Procedure




 Pictorial Diagram of Analyzer Board

 Locations for trimpots and inductors








Loads Using Standard-Value Resistors











   - Install resistors all the way down in the connector, the goal is zero
   lead length

 .

   - Use precision 1% carbon or metal film 1/8th-1/4 watt resistors

  *    *

 *12.5W* = (4) 50-ohm or a single 15W and 82W 1% in parallel

                                    * 50W* = 49.9-ohm  or 100W and 100W in
parallel

                                    * 75W* = 75-ohm or 150W and 150W in
parallel

                                    * 100W* = 100W

                                    *200W* = 200-ohm or 100W + 100W in
series
  *Important Note:** These simple HF loads will not * *always * *be accurate
for SWR checks above * *3**0 MHz. Only precision terminations should be used
in the VHF region**, and even then there can be some errors**.* *The
MFJ-259B does not correct for connector impedance bumps or the electrical
length between an external load and the bridge inside the unit.*
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