The Heathkit HW-101
by Greg Latta, AA8V

Alignment

Click on the image for a super detailed view.

Important Safety Note: Working on or testing equipment such as the Heathkit HW-101 transceiver and the HP-23 power supply is extremely dangerous since very high voltages are present when the equipment is turned on, and may even be present when the equipment is turned off and unplugged. If at all possible, do all work with the equipment off and unpluggedand be sure that the capacitors are properly discharged before working on the equipment. The operator assumes all risk and liability in such matters! Do not work on this type of equipment unless you are experienced with working around very high voltages!

Alignment:

Some General Comments On Alignment: Complete alignment instructions for the HW-101 can be found in the HW-101 manual. However, the instructions in the manual can be confusing at times and often do not explain the reason for the procedure that is being performed. Also, the alignment instructions are based on technology typically available in the 1970s. With modern technology, such as frequency counters and inexpensive digital voltmeters, some of the procedures are much easier.

The alignment instructions given here are an attempt to make the alignment a bit easier by clarifying the procedure, using modern technology when possible, and explaining the reason for each procedure.

Receiver Alignment:

Introduction To Receiver Alignment:
Receivers contain many set-and-forget controls (coils, capacitors, potentiometers, adjustable resistors etc.) that must be set to their proper positions. As a result the receiver will exhibit maximum performance, which includes things such as maximum stability, selectivity, sensitivity, and accurate display of frequency. The process of making all of these set-and-forget adjustments is called alignment.

S Meter Adjustment:
In most situations, the S meter is used to indicate proper alignment, so it must be set first.

The point of this adjustment is to have the S meter read zero on the 80m band with a 50 ohm dummy load connected to the input and the RF gain set to its maximum value.

To adjust the S meter, connect a 50 ohm dummy load (do not use a light bulb!) to the antenna connector, then set the front panel controls as follows:

DRIVER PRESELECTOR - 12 o'clock position
MIC/CW LEVEL - fully counterclockwise
MODE - LSB
BAND - 3.5
MAIN TUNING DIAL (VFO) - 200
FUNCTION - PTT
RF GAIN - fully clockwise
METER - ALC
AF GAIN - 9 o'clock

Adjust the ZERO ADJ control (on the right side of the chassis) for a zero indication on the meter.

Initial Heterodyne Oscillator Coil Alignment:
The output of the heterodyne oscillator for each band must be set to the proper level. An output that is too high is as bad as an output that is too low. Adjustment of the heterodyne oscillator coils is perhaps the most confusing/difficult of all the alignment adjustments. At this point we only do an initial adjustment. Final adjustment is done during transmitter alignment.

What Am I Measuring?:
During this adjustment, the bias on the heterodyne crystal oscillator V19A is measured with a voltmeter. The bias is a direct measure of the oscillator output, with a higher bias indicating higher output.

What Kind of Voltmeter Should I Use?:
Normally, a bias measurement such as this requires the use of a voltmeter with a high (11 Mohm) input impedance. Most modern digital meters (even the cheap ones from, for example, Harbor Freight Tools) meet this requirement, and it is worth purchasing one if you do not already have such a meter. If absolutely necessary an older analog meter with a sensitivity of at least 20,000 ohm/Volt can be used. This is because a relatively low value 4.7 kohm resistor loads the grid in this particular circuit.

Where Do I Connect The Voltmeter:
One lead of the voltmeter is connected to ground. If you are using a digital voltmeter, the negative lead goes to ground. If you are using an analog meter, the positive lead is connected to ground. The other lead is connected to a test point near V19 on the bandpass circuit board. Look at the bandpass circuit board from the front and you will find V19 at top left just in front of the tall crystal calibrator crystal. Immediately to the left of the V19 tube socket you will see a 100 kohm (brown-black-yellow) resistor and a 4.7 kohm (yellow-violet-red) resistor. The test point is in the front of these two resistors and is labeled TP. If there is nothing but a hole where the test point should be, simply connect to the 100 kohm resistor lead closest to you. If your voltmeter reads 0V at TP, use the alternate test point, which is the other end of the 100 kohm resistor. Click on the photo below to see where these test points are located.

Test Point Locations for
Heterodyne Oscillator Coil Alignment

Click Here To Enlarge

What If The Coil Cover Prevents Some Of The Coils From Being Adjusted?
The coils should be adjusted with the coil cover in place. If some of the coils are blocked by the cover, as they were in my HW-101, the holes in the cover must be enlarged. Click here to find out how to modify the coil cover and enlarge the holes.

How Do I Make The Adjustment?:
Set the bandswitch to a particular band and locate the coil for that band. Then make the adjustment by noting the following:

1. You do not necessarily want to adjust each coil for a maximum reading. A reading that is too high is as bad as a reading that is too low. What you want is a reading as high as possible between -0.5 V and -2.0 V, but not exceeding -2.0 V.
2. For each coil you will find a setting that maximizes the reading. If this reading is between -0.5 V and -2.0 V, then leave the coil set at the maximum reading.
3. If the maximum reading is larger than -2.0 V, it must be reduced to -2.0 V. From the peak value, turn the coil in both directions to find out in which direction the value drops more slowly, then turn the coil in that direction until the value drops to -2.0 V.

Where Are The Coils Located?:
This adjustment must be made for all eight heterodyne oscillator coils. Five of the coils, 21 MHz, 7 MHz, 29.5 MHz, 29.0 MHz, and 28 MHz, are marked on the coil cover and are accessed from the bottom of the chassis. The coils for 3.5 MHz, 14 MHz, and 28.5 MHz are marked and adjusted from the top side of the RF-driver board as shown in the diagram below.

Location of the 3.5, 14, and 28.5
Heterodyne Oscillator Coils

Click Here To Enlarge

Receiver IF Alignment:
The receiver 3395 kHz IF section must be adjusted for maximum response at 3395 kHz.. This involves adjusting T201 on the bandpass circuit board and T102, and T103 on the IF circuit board, as shown in the picture below.

Set the front panel controls as follows:

DRIVER PRESELECTOR - 12 o'clock position
MIC/CW LEVEL - fully counterclockwise
MODE - LSB
BAND - 3.5
MAIN TUNING DIAL (VFO) - 400
FUNCTION - PTT
RF GAIN - fully clockwise
METER - ALC
AF GAIN - 9 o'clock

Turn on the calibrator by setting the function switch to CAL and tune in the calibrator signal for maximum response on the S meter.
When tuning in the calibrator signal, turn the DRIVER PRESELECTOR to make sure there is a variation in volume. If there is no variation in volume the signal is a spurious signal and NOT the calibrator signal.

Reset the DRIVER PRESELECTOR to the 12 o'clock position.

Adjust T201 for maximum S meter reading/maximum volume.
Adjust the top and bottom slugs of T102 for maximum S meter reading/maximum volume. To adjust the bottom slug you must have an alignment tool that will pass through the top slug and then fit into the bottom slug.
Adjust T103 for maximum S meter reading/maximum volume.
Touch up all three for maximum S meter reading/maximum volume.

Receiver IF Alignment
Location of T201, T102, and T103

Click Here To Enlarge

General Comments On Aligning An Analog Frequency Display:
In many receivers or transmitters a parallel resonant circuit (tuned circuit) is coupled to an analog readout, typically a slide rule display or, as in the HW-101, a rotary display. The tuned circuit usually consists of a variable capacitor as the main controlling element in parallel with a coil that can be adjusted and then left in place. A trimmer capacitor is also in parallel with the variable capacitor, either mounted directly on the capacitor or as a separate unit.

The goal in aligning such a system is to find the particular combination of trimmer capacitor setting and coil setting that will cause the display to read correctly at two different frequencies typically near the opposite ends of the display (when adjusting a local oscillator), or for S meter readings to be maximized at the calibration frequencies (when adjusting an RF amplifier). Signals at the two desired frequencies must be available from a frequency generator/synthesizer or a crystal calibrator.

It is important to note that in some cases, such as the HW-101, the actual resonant frequency of the tuned circuit is lowest when the analog scale indicates the highestfrequency! For example, in the HW-101, the VFO frequency is lowest (5.000 MHz) when the main tuning is at 500, and highest (5.500 MHz) when the main tuning is at 0. This apparent discrepancy occurs because of the mixing scheme in use. Regardless, the frequency of the tuned circuit is lowest when the variable capacitor is meshed, and highest when it is unmeshed.

To align the system, an iterative procedure is used. The coil and trimmer capacitor are adjusted a little bit each time, and the procedure is used over and over again until the final settings are found.

Here is the general procedure:
1. Set the analog scale and the frequency generator to the calibration frequency where the capacitor plates are more meshed.
Adjust the coil to tune in the calibration signal and/or maximize the S meter reading.

2. Set the analog scale and the frequency generator to the calibration frequency where the capacitor plates are less meshed.
Adjust the trimmer capacitor to tune in the calibration signal and/or maximize the S meter reading.

3. Repeat this procedure over and over again until the calibration signals appear at the correct positions on the analog scale.

It is usually necessary to repeat this procedure many times until the calibration signals appear where they should on the analog scale or the S meter readings are maximized. Sometimes the procedure can be sped up by going "a little too far" with the trimmer capacitor on each run.

VFO Alignment:
Make sure the transceiver has warmed up for at least 30 minutes before making the following adjustments.

Before aligning the VFO, read the previous section General Comments On Aligning An Analog Frequency Display, keeping in mind that the HW-101 VFO is an oscillator and that the VFO frequency goes down as the main tuning display goes up.

Before actually aligning the VFO, the rotary scale must be set properly on the main tuning shaft. When the main tuning control is rotated counterclockwise as far as it will go (do not force it) the scale should be positioned as shown in the diagram below, with the end of the scale (the white bar) directly under the indicator line.

The scale is connected to the main tuning shaft via a slip clutch. The scale can be held in place by pressing and holding the Zero Set button. The main tuning knob can then be turned to rotate the main tuning shaft while the scale is held in place. This alters the position of the scale relative to the shaft.

To Align The Frequency Scale:
Rotate the main tuning dial counterclockwise until it stops. Do not force it. If the end of the scale is too far to the right, back up the main tuning knob until the reading is about 475. Press and hold Zero Set while you turn the main tuning knob about 1/4 turn to the right (clockwise). Recheck the setting. If still too far to the right, repeat the process until the scale is positioned correctly.

If the scale is too far to the left, back up the main tuning dial until the reading is about 475. Press and hold Zero Set while you turn the main tuning knob about 1/4 turn to the left (counterclockwise). If still too far to the left, repeat the process until the scale is positioned correctly.

Proper Position of Analog Scale When Main Tuning Dial
Is Turned Counterclockwise As Far As It Will Go

Click Here To Enlarge

To Align The VFO Using A Frequency Counter:
Since the VFO is an oscillator that has a buffer stage to isolate it, the easiest way to align the VFO is to use an accurate frequency counter. There is an RCA connector on the rear of the VFO housing. Disconnect the cable currently in the jack and connect the frequency counter to the jack. See the diagram below to see where to connect the counter and for the location of the VFO adjustments.

1. Turn the main tuning dial counterclockwise until it reads exactly 500. Adjust the VFO coil so that the counter reads exactly 5000 kHz.
2. Rotate the main tuning dial clockwise until it reads exactly 0. Adjust the trimmer capacitor(s) on the side of the VFO enclosure so that the counter reads exactly 5500 kHz.
3. Reset the dial to 500 and readjust the VFO coil so the counter again reads 5000 kHz.
4. Reset the dial to 0 and adjust the trimmer(s) so that the counter again reads 5500 kHz.
5. Repeat this procedure as many times as necessary until the counter reads 5000 kHz at the 500 mark and 5500 kHz at the 0 mark. This could take quite a few repetitions. Sometimes the procedure can be sped up by going "a little too far" with the trimmer capacitor on each run.

To Align The VFO Using The Crystal Calibrator:
Lacking a frequency counter, the transceiver crystal calibrator can be used. For highest accuracy the crystal calibrator should be calibrated before aligning the VFO. Crystal calibrator alignment is explained in the transmitter alignment section. Note that the Heathkit manual is not concerned with with prior calibration of the crystal calibrator, so this step may not be necessary. See the diagram below for the location of the VFO coil and the calibration trimmer capacitors.

1. Set up the transceiver to receive on the 3.5 MHz band.
2. Turn on the calibrator by setting the mode switch to CAL and find the calibrator signal at the top end of the main tuning dial. This should be somewhere above 475 on the dial.
3. Adjust the tuning for zero beat and, while carefully adjusting the VFO coil, "walk" the calibrator signal until zero beat occurs at 500 on the dial.
4. Rotate the tuning dial to the the bottom of the scale and find the calibrator signal around 0 at the bottom of the scale. This should be somewhere below 25 on the dial.
5. Adjust the tuning for zero beat and, while carefully adjusting the trimmer capacitor(s), "walk" the calibrator signal until zero beat occurs at 0 on the dial.
6. Go back up to the top of the scale and find the calibrator signal around 500. Repeat step 3.
7. Go back to the bottom of the scale and find the calibrator signal around 0. Repeat step 5.
8. Repeat this procedure until the calibrator signal is zero beat at the 0 mark and the 500 mark. This could take quite a few repetitions.

Since it is possible, in an extreme case, to be 100 kHz off, it is a good idea to tune in a signal of known frequency and make sure it comes in at the proper place on the dial.

Location of VFO Adjustments and Connections

Click Here To Enlarge

Driver Grid And Plate Coil Alignment:
Make sure the transceiver has warmed up for at least 30 minutes before making the following adjustments.

Though the driver grid and plate coils are used both by the receiver and the transmitter, they are adjusted in receive mode. The adjustments are easy to make. However, because of the circuit design, the adjustments interact with each other . For example, changing the adjustment of the 21.0 MHz coils will also affect the 14.0 MHz and 7.0 MHz bands. As a result, they must always be adjusted in the proper order. This also means you can't just touch up the coils for one band without redoing all of the others.

The 3.5 MHz coils are adjusted first, followed by the 29 MHz, 21 MHz, 14 MHz, and 7 MHz coils. They must be adjusted in this order.

The actual frequencies used for adjustment are 3.7 MHz, 29.2 MHz, 21.2 MHz, 14.2 MHz, and 7.2 MHz. When adjusting any set of coils, the driver preselector control must be set to the proper position as shown below:

Preselector Settings for
Driver Grid And Plate Coil Alignment

Click Here To Enlarge

Connect a 50 ohm dummy load to the transceiver antenna connector.

Set the front panel controls as follows:

DRIVER PRESELECTOR - 12 o'clock position
MIC/CW LEVEL - fully counterclockwise
MODE - LSB
BAND - 3.5
MAIN TUNING DIAL (VFO) - 200
FUNCTION - PTT
RF GAIN - fully clockwise
METER - ALC
AF GAIN - 9 o'clock

When tuning in any calibrator signal, turn the DRIVER PRESELECTOR to make sure there is a variation in volume. If there is no variation in volume the signal is a spurious signal and NOT the calibrator signal. When you are finished verifying the calibrator signal, reset the DRIVER PRESELECTOR control to the proper position as shown in the picture above.

Turn on the crystal calibrator by moving the function switch to CAL.

With the band selector in the 3.5 MHz position tune in the calibrator signal near the 200 position on the main tuning dial. Adjust the main tuning dial for a maximum S meter reading.
Be sure the DRIVER PRESELECTOR is in the 3.5 position as shown above and adjust the coils marked 3.5 for maximum S meter reading.

Change the band selector to the 29.0 MHz position. Tune in the calibrator signal near the 200 position on the main tuning dial and adjust for a maximum S meter reading..
Be sure the DRIVER PRESELECTOR is in the 29.2 position as shown above and adjust the coils marked 29 for a maximum S meter reading.

Change the band selector to the 21.0 MHz position. Tune in the calibrator signal near the 200 position on the main tuning dial and adjust for a maximum S meter reading..
Be sure the DRIVER PRESELECTOR is in the 21 position as shown above and adjust the coils marked 21 for a maximum S meter reading.

Change the band selector to the 14.0 MHz position. Tune in the calibrator signal near the 200 position on the main tuning dial and adjust for a maximum S meter reading..
Be sure the DRIVER PRESELECTOR is in the 14 position as shown above and adjust the coils marked 14 for a maximum S meter reading.

Change the band selector to the 7.0 MHz position. Tune in the calibrator signal near the 200 position on the main tuning dial and adjust for a maximum S meter reading..
Be sure the DRIVER PRESELECTOR is in the 7 position as shown above and adjust the coils marked 7 for a maximum S meter reading.

Remember, these adjustments must always be done in sequence since they interact with one another.

Transmitter Alignment:

Introduction To Transmitter Alignment:
Because many receiver circuits are shared with the transmitter, you must align the receiver first before aligning the transmitter.

When making any transmitter adjustments, be sure a 50 ohm dummy load (do NOT use a light bulb) is connected to the transceiver.

Transmitter Bias Adjustment:
The first transmitter adjustment is to set the bias on the final amplifier tubes to the correct value. This is done by putting the transmitter in transmit mode while in LSB mode with no drive on the final amplifier tubes and turning the BIAS control (on the right side of the transceiver) so that the cathode current reads the correct value.

Important Note: Placing the transmitter in transmit mode for more than a few seconds with the bias at the wrong value can damage the final amplifier tubes.

Set the front panel controls as shown below:

DRIVER PRESELECTOR - 12 o'clock position
MIC/CW LEVEL - fully counterclockwise
FINAL (round knob) - to 10 o'clock
FINAL (lever knob) - to 4 o'clock
MODE - LSB
BAND - 3.5
MAIN TUNING DIAL (VFO) - 200
FUNCTION - PTT
METER - PLATE

Press the microphone button (or short the PTT pin on the microphone jack to ground) and turn the bias control (on the right side) of the Transceiver to set the meter needle at the "3" mark on the meter scale. There is an arrow above the "3" on the meter scale to help identify the correct setting.

Carrier Isolation Amplifier Alignment:
In this step, transformer T1 at the output of the balanced modulator is adjusted for maximum response.

Be sure a 50 ohm dummy load (do NOT use a light bulb) is connected to the Transceiver.
Set the controls as shown above for Transmitter Bias Adjustment and verify that the transmitter bias is set correctly.

then:

Set the METER switch to REL PWR and press the microphone button (or short the PTT pin on the microphone jack to ground). The meter should read zero.
Set the MODE switch to the TUNE position and slowly turn the MIC/CW LEVEL control clockwise until there is an indication of RF output of not more than 6 on the meter
Adjust the DRIVER PRESELECTOR and peak the RF output. Reduce the MIC/CW LEVEL to keep the reading below 6.
Adjust the FINAL tune (round knob) and peak the RF output. Reduce the MIC/CW LEVEL to keep the reading below 6.
Adjust the MIC/CW LEVEL control for an RF output of not more than 3 on the meter.
Adjust transformer T1 for a maximum reading on the meter.
Readjust the MIC/CW LEVEL control for an RF output of not more than 3 on the meter.
Again adjust transformer T1 on the modulator circuit board for a maximum reading on the meter. See the diagram below.
Set the MODE switch back to LSB.

Location of T1

Click Here To Enlarge

Preliminary Final Amplifier Neutralization:
Neutralization is one of the most important transmitter adjustments. If not neutralized properly, the transmitter can break into self oscillation, causing illegal spurious emissions and distortion.
Neutralization is required because unintentional/unavoidable positive feedback through the tube being neutralized can cause it to self oscillate. To prevent this self oscillation, some of the output is intentionally fed back to the input out of phase to cancel the undesired positive feedback. Since the amount of feedback needed varies with the particular tube(s) and the surrounding circuitry, it must be done for every individual case. If the tube(s) are changed or the circuit is rearranged, it must be redone.

For a power amplifier such as that in the HW-101, there is an easy way to tell if the circuit is neutralized:
When the plate tuning (FINAL control on the HW-101) is adjusted, a dip in the plate/cathode current will be observed. When looking at the RF output, there will be a peak in the RF output.. When the dip in the plate/cathode current occurs at the same setting of the FINAL control where the peak in the RF output occurs, the amplifier is neutralized.

When making this adjustment, you can use the REL. POWER and PLATE positions of the METER switch to read the output power and cathode current respectively. This, however, requires constantly switching the meter from one position to another. It is much easier to use an SWR meter or wattmeter connected to the Transceiver output to read the RF output. The METER switch can then be left in the PLATE position.

Theoretically, the neutralization should not depend on frequency, but in reality it does. In this case, the final amplifier will initially be neutralized at 3.5 MHz. Then, after neutralizing the driver stage, it will be touched up at 14 MHz.

As a first step, Heathkit says to rotate the neutralizing capacitor fully clockwise until resistance is felt, and then turn it counterclockwise one full turn. But this is for a newly built HW-101. For an HW-101 that has been in service, it is safe to assume that it is already near proper neutralization, and to avoid this initial step.

Location of Neutralizing Capacitor
and Driver Neutralizing Wire

Click Here To Enlarge

The neutralizing capacitor is mounted on the front of the final amplifier cage. See the figure above.
The following procedure may seem confusing, but once you do it a couple of times you will understand the general idea.

When performing the following steps, keep the Transceiver at full power output for the minimum time necessary. Then place the MODE switch at LSB and let the final stage tubes cool for at least 30s before continuing.

To perform the initial neutralization:

1. Be sure the controls are set up as in the previous step, Carrier Isolation Amplifier Alignment.
2. Turn the MODE switch to TUNE and adjust the MIC/CW LEVEL control and FINAL tune control for maximum output (either on the REL. PWR meter or on the SWR/wattmeter). Go back to LSB and allow the finals to cool. Carefully note the position of the FINAL tune control.
3. Be sure the METER switch is set to PLATE, and activate TUNE again. While TUNE is activated, move the FINAL tune control carefully back and forth about the position noted earlier and verify that the plate current is at a minimum in the same position as when the output is a maximum. Go back to LSB.
4 If maximum output and minimum plate current do not occur at the same setting of the FINAL tuning control, make a mental note of how far they are apart on the FINAL tuning control. Note the position of the neutralizing capacitor, then rotate it a small amount (1/16 - 1/8 turn) clockwise and repeat the previous steps 2 and 3.
5. If the maximum and minimum are farther apart on the FINAL tuning control, you went the wrong way with the neutralizing capacitor. Return it to its starting point and then go counterclockwise on the neutralizing capacitor. If the maximum and minimum got closer together, rotate the neutralizing capacitor a little further clockwise and recheck.
6. Continue the previous steps until you find the position of the neutralizing capacitor where maximum output and minimum plate current occur at the same setting of the FINAL tuning control.

Carrier Null Adjustment:
The carrier null adjustment reduces the carrier in the output to the lowest possible level. This is a compromise adjustment, because the best setting is different for LSB and USB. A variety of indicators can be used to indicate the carrier level in the output. These include the following:

1. An RF voltmeter connected to the output
2. An oscilloscope connected to the output
3. Listening to the output on a nearby receiver tuned to the carrier frequency
4. An RF wattmeter/SWR meter connected to the output
5. The REL. PWR meter on the HW-101

For best results, either an RF voltmeter, oscilloscope, or listening on a receiver should be used. Lacking these, adequate results can be obtained using the REL. PWR meter.

In all cases a 50 ohm dummy load (not a light bulb) must be connected to the output. If you are using an RF voltmeter or oscilloscope, use a "T" connector on the output so both the dummy load and voltmeter or oscilloscope are connected at the same time. If you are using a receiver, do NOT connect it to the output!
:
1. Tune the transceiver up on the 80m band at 3700 kHz.
2. Set the controls as follows:
METER - REL. PWR
FUNCTION - PTT
MODE - LSB
MIC/CW LEVEL - fully counterclockwise.
3. Activate PTT and adjust the carrier null control for minimum RF output.
4. Adjust the carrier null capacitor for minimum RF output.
5. Switch to USB and repeat steps 3 and 4.
6. Repeat the above steps until the RF output is about the same both in LSB and USB. This is a compromise. You want minimum RF output, but you want it to be the same on LSB and USB.

See the diagram below for the location of the carrier null control and carrier null capacitor.

Location of Carrier Null Control
and Carrier Null Capacitor

Click Here To Enlarge

Final Heterodyne Oscillator Coil Alignment:
Before you perform this step, be sure you have done the initial heterodyne oscillator alignment.
Be sure a 50 ohm dummy load (do not use a light bulb) is connected to the transceiver.

To perform the final heterodyne oscillator coil alignment:

1. Set the METER switch to REL. PWR

2. Set the BAND switch to 3.5 and the MAIN TUNING dial to 200 (3700 kHz).
3. Tune up the transceiver on 3700 kHz for maximum output as indicated on the meter.
3. Switch the MODE switch to TUNE and use the MIC/CW LEVEL control to obtain a reading between 3 and 9 on the meter.
4. Adjust heterodyne oscillator coil 3.5 for maximum output.
5. Repeat the following adjustment for each position of the BAND switch, except adjust the coil with the same number as the BAND switch. Five of the coils, 21 MHz, 7 MHz, 29.5 MHz, 29.0 MHz, and 28 MHz, are marked on the coil cover and are accessed from the bottom of the chassis. The coils for 3.5 MHz, 14 MHz, and 28.5 MHz are marked and adjusted from the top side of the RF driver board.

Driver Neutralization:
In the HW-101, the driver stage must also be neutralized. The neutralizing capacitor is a white wire attached to the frame of the front driver preselector capacitor that runs through a hole in the RF Driver circuit board. For the location of the wire, see the figure under preliminary final amplifier neutralization. Note that the frame of this capacitor is not directly grounded. Rather, it is connected to ground through a 100 ohm resistor. When the white wire is inserted through the circuit board, the wire is near the plate lead of the 6CL6 driver tube. The capacitance between the two forms the driver neutralizing capacitor, and it is adjusted by varying the amount of wire stuck through the hole. Inserting more wire through the hole increases the capacitance. Pulling the wire out decreases the capacitance. Crude, but it works.

It is not possible to monitor the output of the driver or the driver plate current, so proper neutralization must be determined differently than in the case of the final amplifier. For the driver, proper neutralization is indicated by the lack of erratic behavior when the DRIVER PRESELECTOR is adjusted.

To neutralize the driver:

Set the BAND switch to 21.0 MHz
Set the MAIN TUNING to read 21.2 MHz
Go into TUNE mode and adjust the DRIVER PRESELECTOR, FINAL TUNE, and LOAD controls for maximum RF output.
Turn the DRIVER PRESELECTOR control back and forth to see if this produces a smooth peaking in RF output.
If turning the DRIVER PRESELECTOR control causes ragged or uneven changes in the RF output, readjust the position of, or bend, the free end of the driver neutralizing wire to produce a smooth peaking in the RF output.

Final Amplifier Neutralization Touch Up:
Repeat the preliminary final amplifier neutralization, except perform the procedure at 14.2 MHz, where the adjustment is more sensitive.

Crystal Calibrator Alignment:
In this adjustment, the crystal calibrator is set to a frequency of exactly 100,000.0 Hz. You might be tempted to use a frequency counter to make this adjustment, but unless the counter is a laboratory quality instrument with a resolution of 0.1 Hz or 0.01 Hz it will not be accurate enough. The calibrator frequency must be accurate within a fraction of a Hz. This is most easily done be comparing a high harmonic of the calibrator signal to another signal of known frequency, for example WWV. You will need a receiver capable of receiving WWV at 10 MHz or 15 MHz.

To calibrate the crystal calibrator:

1. Use your receiver to tune in WWV at 10 MHz or 15 MHz. This may be possible only at certain times of the day.
2. Be sure that the MIC/CW LEVEL control is fully counterclockwise so there is no way the transmitter can put out any signal.
3. Connect a random length of wire from the transceiver output to the external receiver antenna.
4. Tune the external receiver to WWV at 10 MHz or 15 MHz.
5. Set the FUNCTION switch to CAL and carefully adjust the CAL CRYSTAL capacitor on the bandpass circuit board to zero beat the calibrate signal with the WWV signal. The location of the Cal Crystal capacitor is shown in the diagram below. Wait until there is no modulation present on WWV to make this adjustment. Listen very carefully. When you get close to the proper adjustment you will hear the noise in the background pulsate. Try to get the pulsation to stop if possible. If you can't get it to stop, just get it to go as slow as possible.

Location of Crystal
Calibrator Adjustment

Click Here To Enlarge

VFO Shifter Adjustment:
When switching from LSB to USB, the carrier oscillator frequency is changed. This will cause the reading of the MAIN TUNING dial to read incorrectly unless the VFO is also shifted when changing from LSB to USB. This is accomplished be electronically switching a trimmer capacitor in and out when changing from LSB to USB. This capacitor is mounted on the top side of the VFO enclosure. Do NOT confuse it with the trimmer capacitors on the left side of the enclosure.

To adjust the shift capacitor:

1. Adjust the MAIN TUNING dial to 200 kHz and the BAND switch to 3.5.
2. Set the FUNCTION switch to CAL to turn on the crystal calibrator.
3. Turn the MODE switch to USB.
4. Carefully zero beat the calibrator signal. Use the MAIN TUNING dial and peak the DRIVER/PRESELECTOR control.
5. Set the MODE switch to LSB. Be careful not to touch the MAIN TUNING dial. Note that the calibrator signal may or may not be zero beat in the LSB position.
6. Turn the SHIFT ADJUST on the top of the VFO for an exact zero beat in the LSB mode. See the diagram below for the location of the shift adjust capacitor.
7. Recheck for zero beat in the USB mode and repeat the adjustment until you have zero beat in both LSB and USB at the same setting of the MAIN TUNING dial.

Location of VFO Shift Adjust Capacitor

Click Here To Enlarge

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