RigPix FT-101B Database Receiver Instructions

How many times have you heard on the air the remark “my FT101B is a little deaf”? My own unit was not deaf but its performance was well down compared with a Drake RC4. Not now!

Always looking to improve the performance, the usual modifications published were tried and found wanting. Determined to find a way, it was decided to improve the signal between the 3SK40 RF stage and the antenna input. No claim is made for the originality of the circuit as shown, but the initiative to wire it up and try it.

Assembly and Mounting

• The prototype was built on a piece of vero board, 11 x 23 holes, and laid out as shown in Figure 1.
• The vero board is mounted on the top of PB-1181-B by attaching it by four wires to the earth rail and the earth of the PB-1181-B board, as shown in Figure 2.
• Take the PB-1181-B board out from the FT101B and withdraw the 3SK40 RF stage transistor from its socket for safety.

FIGURE 1: Component layout.

Installation and Wiring

• Lift the end of the 100 pF capacitor C1 that connects from pin 8 to gate 1 of the 3SK40 at the gate 1 end and run a wire from the capacitor to gate 1 of the MPF121. On the opposite side of the board connect a wire from gate 1 of the 3SK40 to the 100 pF output of the BC308. Also connect a wire from pin 14 to the plus input of the added board. Replace the 3SK40 in its socket and replace the board in the FT101B.
• You may have to re-align the receiver circuits on 28 MHz A, B, C and D. On the other lower frequency bands the pre-selector tuning will take up any difference. If not, re-align all circuits as per the instruction manual. The extra gain will mean the “S” meter will need to be adjusted at 14200 MHz as per the instruction manual.
• If, when you replace the board and switch-on, there appears to be an intermittent fault such as “crackling” or “popping” noises when the board is touched or moved, check the lead between C1 and the gate of the MPF121. Where the lead leaves C1 it passes between two resistors and a capacitor. Part these components so that the lead is clear, does not touch them, and is kept well down near the surface of the board. This should cure the slight regeneration which causes these symptoms.

Note: The circuit as originally submitted by 5KL showed a resistor across the MPF121 drain coil. Correspondence with the author indicated that this was one of the measures tried to reduce regeneration, but later proved unnecessary. Possibly a higher than normal gain FET may require a resistor here in the order of 220 ohms to 1k.—Tech. Ed.

• In my case, due to the extra gain I find that on 3.5 and 7 MHz the RF attenuator can be used to reduce the gain to that of the other bands, which aids the selectivity on these two bands.
• Now sit back and notice the new sensitivity of your receiver and how the signals stand out above the noise level.

Good luck with the modification — Clarry.

FIGURE 2: Connection diagram.

FIGURE 3: Circuit diagram.

Component Specifications

• L1: 8 turns nylon coated jumper wire close-wound on 5/32 in. diameter.
• * : Can be varied from 220 to 1k ohms. The higher value will drop the gain slightly but aid selectivity.

INTERCONNECTIONS

If a tuned open wire transmission line, or a long wire
antenna is used, a suitable antenna tuner must be used
between the antenna and the transceiver to provide an
impedance match between the unbalanced coaxial output of the transceiver and the balanced open-wire feeder
or long wire.
For mobile operation, most of the commercially available antennas on the market will give good results with
coaxial cable is securely grounded to the chassis. of
the vehicle at the antenna mount. Adjust the antenna
length carefully for minimum SWR after installation.

CONTROLS AND SWITCHES

The transceiver has been specifically designed for ease
of operation and versatility. All controls have been
preset at the factory. Several of the controls are
unusual in operation, and improper adjustment may
result in signals of poor quality. The various front
panel controls and their functions are described in the
following section. Be certain that you understand
thoroughly the function of each control before operating
the transceiver.

(1) VFO Select Switch;
This switch provides selection of the companion FV-101B
external VFO or two fixed crystal oscillator positions.
Normal operation of the transceiver VFO requires that
the switch be placed in the “INT” position.
INT.- FT-101B/277B VFO controls both trans
mitter and receiver frequencies.
RX EXT–FV-101B/277B EXTERNAL VFO controls the
receiver frequency and the FT-101B/277B
VFO controls transmitter output frequency.
TX EXT–FV-101B/277B EXTERNAL VFO controls the
transmitter output frequency and the FT-101B
/277B VFO controls the receiver frequency.
EXT.. FV-101B/277B EXTERNAL VFO controls
both transmitter and receiver frequencies.
CH1, CH2–Provides crystal control of the transceiver.
Proper crystals must be installed on PB-1344
crystal oscillator board, for crystal controlled
operation.
(2) Mode Switch; (LSB-USB-TUNE-CW-AM)
The mode switch is a five-position switch. This switch
is used to select the mode of operation; LSB, USB,
AM, CW, or TUNE position. In the AM, CW and
TUNE positions, a separate crystal is used to shift the
carrier frequency into the filter passband.
(3) RF GAIN/AF GAIN;
The RF GAIN/and AF GAIN controls are mounted
on concentric shafts. RF GAIN control (lever control)
varies the gain of the receiver RF and IF amplifier.
Maximum sensitivity is obtained with the control set
at 10 (fully clockwise).
The AF GAIN control (round knob) adjusts the audio
output level at the speaker and phone jack. Clockwise
rotation increases the audio output.
(4) Tuning Knob
The tuning knob located directly below the main dial
window in combination with the band switch determines
the actual frequency of operation.
The VFO drive mechanism consists of a precision
spring loaded split gear system in combination with
a planetary drive unit to provide zero backlash at low
tuning rates. Each revolution of the tuning knob results
in a frequency change of 16 KHz as indicated on the
skirt surrounding the tuning knob.
(5) BAND Switch;
The band switch is an eleven-position switch used to
select the desired band for receiving or transmitting.
The band indication is color coded to guide the operator selecting in the proper frequency scale for each band.
6
(6) CLARIFIER:
The clarifier control provides a means for tuning the
receiver frequency 3 KHz to either side of the transmitting frequency. Thus, it is possible to set the pitch
of the voice you are receiving to the most readable
point without affecting your transmitting frequency.
Its use is particularly valuable in “net” operation
Where several participants may be transmitting slightly
off frequency. The clarifier control may be switched
off and the receiver locked to the transmitting frequency
by setting the clarifier control to the OFF position.
Normally, you will want to keep the clarifier in the
OFF position until the initial contact is made. The
clarifier control may then be used to zero-in and correct
the any drift on the received signal.
(7) PRESELECT;
This control pretunes the signal circuits for both transmit and receive. The preselect circuit provides continu
ous permiability tuning throughout the frequency range
of the transceiver.
(8) MIC GAIN/CARRIER ;
The MIC GAIN/CARRIER controls are mounted on concentric shafts. The carrier control (lever control) varies
the amount of the carrier in the CW, AM and TUNE
modes of operation.
The MIC GAIN control (round knob) varies the audio
level from the microphone amplifier stage. The control
has sufficient range to permit the use of any high
impedance crystal or dynamic microphone. Both controls
have maximum gain with the control set at 10 (fully
clockwise).
(9) PLATE;
Tunes plate circuit of the final amplifier.
(10) LOADING;
Tunes the output circuit of the pi network to match
antenna and feed line impedance.
(A) POWER
Main switch turns transceiver “on” for both AC and
DC operation.
(B) HEATER
With this switch in the down position, the transmitter
tube heaters are turned off. This reduces battery drain
to 0.5 amp and thus permits long periods of listening
without excessive battery drain. Pushing the rocker
switch to the upper position provides supply voltage
to the tube heaters. After a 30 second warm-up, the
transmitter is ready for operation. This switch operates
in both DC and AC modes.
(C) MOX-PTT-VOX
This slide switch selects desired transmitter mode for
both microphone and key operation.
MOX-(Manual transmit switch position)
Locks transmitter “ON” and must be returned
to PTT position for receiver recovery.
PTT-(Push-to-talk)
Locks transmitter “ON” when microphone switch
is depressed. Receiver recovers automatically when
microphone switch is released.
VOX-(Voice operated transmit or break-in CW operation)
This switch position allows the operator to actuate the transmitter by simply speaking into the
microphone. Receiver recovers automatically when
the operator stop speaking.
For break-in CW, the VOX system will actuate
the transmitter each time the key is depressed,
receiver recovers each time key is released.
(D) NB (NOISE BLANKER)
In upper position, the noise blanker is placed in the
circuit and eliminates noise pulses caused by auto
ignition.
(E) RF ATT (RF Attenuator)
This switch provides insertion of a 20 db attenuator
in the incoming signal path to minimize cross modulation which may be caused by extremely strong local
signals.
(F) 25 KHz/100 KHz (CALIBRATOR)
The 100 KHz crystal oscillator is used to calibrate
the receiver. In the 25 KHz position, the 25 KHz
multivibrator generates a marker signal at each 25
KHz point on the dial. Clarifier control must be in
the “OFF” position when setting calibration.
(G) PHONE
Headphone may be inserted in this jack for private
listening. The internal speaker is disconnected when
the headphone plug is inserted. Any high quality headphone may be used.
(H) MIC
Microphone Jack. Four pin connector is used for microphone input, and push to talk relay actuation.
(1) METER
Selects the meter mode to read PA cathode current (I.C.),
relative power output (PO), or ALC feedback voltage.
REAR APRON CONNECTIONS AND CONT

INITIAL CHECK

The tuning procedure of the transceiver is not
complicated. however, care should be exercised
when tuning to insure peak performance of the equipment. The following paragraphs describe the procedure
for receiver and transmitter tuning.
INITIAL CHECK
Before connecting the transceiver to a power source,
carefully examine the unit for any visible damage. Check
that all modules and crystals are firmly in place and
that controls and switches are operating normally. Ensure that voltage specification marked on rear panel
matches the supply voltage.
FREQUENCY SELECTION
The main tuning dial is color coded with the band
selector switch for proper frequency read out. When
band selected is marked in Red, the operator reads the
Red numbers on the main tuning dial. When for
example the band selected is marked in White on transceiver front panel, the operator reads the Black numbers
on main tuning dial.
The main tuning dial is marked in 25 KHz increments
between each 100 KHz segment. This provides a
course frequency setting within the band. The dial skirt
surrounding the tuning knob is marked in 1 KHz increments and provides for fine settings of the transceiver operating frequency.
Following the example shown, familiarize yourself with
the relationship of main and skirt dial frequency readout.
RECEIVER CALIBRATION:
Preset the controls and switches as indicated:
VFO Selector ….. INT (internal)
MOX-PTT-VOX…………… PTT
POWER
RF GAIN
AF GAIN
BAND
MODE
TUNING
ON (upper position)
Maximum
As required
… Desired band
…. Desired mode
.100 KHz point
PRESELECTOR….. Desired band segment
CLARIFIER
RF ATT…
OFF
OFF
CALIBRATOR. 100 KHz
To calibrate, set the TUNING control to the 100 KHz
point on the dial nearest the desired frequency. Tune
the preselector for maximum “S” meter deflection. Tune
the transceiver to the 100 KHz calibrator signal for
zero beat. Two signals may be heard near the 100
KHz point. One of these is a signal ſeeding through
the IF stages. Always calibrate to the stronger of
these two signals. To calibrate, hold tuning knob firmly
at zero beat point and rotate skirt vernier dial to
zero position. The skirt vernier dial surrounds the
tuning knob and is held in position by a friction
locking device. This dial is easily movable by hand
but will retain its position after calibration. The transceiver must be calibrated when changing mode of operation of LSB, USB. AM or CW.
Switch the calibrator to the 25 KHz position and note
that the calibrator signal can be heard at every 25
KHz point. The calibrator switch should be in the
OFF position in normal use of the transceiver.
100
200
790
60
For bands 40-20-15-10A-10C read Black scale on main
dial. Setting shown in the example would then be 148
KHz plus the starting band edge frequency in MHz.
For example, on 40 meters the frequency would be
7.148 MHz. On 20 meters, 14.148 MHz, etc.
For bands 160-80-10B-10D read Red scale on main dial.
Settings shown in the example would then read 648 KHz
For example, on 80 meters the frequency would be 3.648
MHz, on 10B, 28.648 MHz. etc.
9
TRANSMITTER TUNE-UP
The following tune-up procedure must be performed
prior to selection of desired operating mode, LSB, USB,
CW, or AM. See paragraphs relating to the specific
mode after basic transmitter tune-up.
Connect dummy load or matched antenna to the coaхial fitting on rear apron, and preset controls as follows:
POWER
HEATER
OFF
ON
0 (fully counter-clockwise)
MODE .TUNE
CARRIER
BAND
TUNING
Desired band
PRESELECTOR.. Desired band segment
Desired frequency
Desired band segment
To position shown in table
PLATE
LOADING
METER IC
VFO SELECT INT
MOX-PTT-VOX PTT
LOADING POSITIONS
BAND LOADING
160. .5
80 5
40 5 1/2
20 3 1/2
15 3
10A 4
10B 4
10C 4
10D 4
NOTE: Loading positions are nominal, Slight variations
from positions shown are to be expected.
With the transceiver turned on, allow 60 seconds for
warm-up of the transmitter tubes. Be certain that
accessory plug is in the accessory socket. The heater
voltage to the final tubes is supplied through pins 1
and 2 of the accessory plug.
Set the ” MOX-PTT-VOX” switch to MOX position. Meter
will now read Final Amplifier resting cathode current.
This should be set at 50 mA with the BIAS control
located under the top cover near the rear of the set.
Switch the meter, to ALC position and adjust ALC
control under the top cover for full scale deflection
of the meter. Return meter switch to IC position and
“MOX-PTT-VOX” switch to PTT position.
PRE-TUNING
1. Adjust “PRESELECT” for maximum receiver noise
level.
2. Place “MOX-PTT-VOX” switch “MOX” position.
3. Rotate “CARRIER” control arm until meter rises
just above normal idling current. (60 mA)
4. Adjust “PRESELECT” for maximum meter reading.
(Caution: if meter exceeds.1 (100 mA), reduce
“CARRIER”)
5. Rotate “PLATE” control for minimum meter reading.
(Plate Dip)
6. Return “MOX-PTT-VOX” switch to PTT position.
The transmitter is now pretuned to the desired frequency.
Final peak tuning is accomplished by carefully following
the final tuning procedure.
FINAL TUNING
Final peak tuning utilizes the meter relative power
output position (P.O.). At full transmit power the meter
will read approximately one-half to two-thirds full scale
into a matched antenna load. If during final tune-up
it is noted that the meter indication exceeds full scale,
discontinue tune-up. Off scale meter indications are the
result of reflected RF due to high VSWR and corrective action should be taken before attempting final tune
up.
CAUTION
Exceeding the time limits noted during
final tuning may result in destruction of
final output tubes.
1. Set meter switch to P.O. position, rotate “CARRIER”
control arm fully clockwise to position 10.
2. Momentarily set ” MOX-PTT-VOX” switch to ” MOX”
3.
(10 second maximum), and rotate “PRESELECT”
control for maximum meter reading. Return “MOX”
to PTT position.
Momentarily set “MOX-PTT-VOX” switch to “MOX”
(10 second maximum) and increase or decrease
“LOADING” control for maximum meter reading.
Return “MOX” to PTT position.
4. Momentarily set “MOX-PTT-VOX” switch to “MОХ”
(10 second maximum) and increase or decrease
“PLATE” control for maximum meter reading. Return “MOX” to PTT position.
5. Repeat steps 3 and 4 úntil maximum meter reading
is obtained.
-10
The transmitter is now tuned for maximum output.
Return “CARRIER” control arm fully counter-clockwise to zero position. Return meter switch to IC position and MODE switch to desired operating mode.
NOTE: Moving the “MOX-PTT-VOX” switch to the
“MOX” position in the above steps may be
eliminated by simply operating the microphone
PTT switch when microphone is attached to
the transceiver.
SSB OPERATION
After completion of tuning, set MODE switch to LSB
or USB. Set the METER switch to ALC position. Set
the “MOX-PTT-VOX” switch to the PTT position and
advance the MIC GAIN control until the meter kicks
down to midscale of green colored portion when speaking
normally into the microphone.
Set the “MOX-PTT-VOX” switch to VOX position.
For VOX operation, adjust VOX GAIN potentiometer
under the top cover until voice actuates the transceiver. Set the ANTITRIP potentiometer to the minimum point to prevent the speaker output from tripping
the VOX. Do not use more VOX gain or ANTITRIP
gain than necessary. Adjust the DELAY potentiometer
under the top cover for suitable release time.
NOTE: When meter is set to IC. voice modulation
peaks will indicate 150-200 mA. Actual peak
current, however, is approximately 2 times
the indicated value.
CAUTION
CARE must be taken to avoid an excessive
drive to prevent spurious radiation. Maximum
key down current should be kept within 330
mA for the bands under 15 meter and 280 mA
for 10 meter band.
CW OPERATION
Upon completion final tuning, insert key plug in jack
marked “KEY” on rear apron of the transceiver. Power
output from the transmitter is determined by the
“CARRIER” control arm position. The operator may
select any power output desired by simply rotating
the “CARRIER” control within the limits of its range
from zero to ten.
The transceiver may be operated manually or break-in
by setting the “MOX-PTT-VOX” switch to either MOX
(manual) or VOX (break-in) for the desired mode of
operation.
NOTE: Insertion of the key plug automatically disconnects the bias supply to the PA tubes,
therefore, with the key plug inserted Final
Amplifier bias current will not be indicated
when meter is in the IC position.
AM OPERATION
AM operation of the transceiver is accomplished by
setting the MODE switch to the AM position and
inserting the proper amount of “CARRIER” with the
“CARRIER” control.
After completion basic transmitter tune-up. place the
MODE switch in the AM position and rotate “CARRIER”
control arm until meter reads 15(150 mA) in the IC
position. While speaking into the microphone normally,
increase MIC GAIN until the meter indicates very
slight movement with voice peaks.
Care must be taken in adjusting MIC GAIN control
to assure that the “CARRIER” control arm is not
rotated causing an increase in “CARRIER” level. Do
not exceed 15(150 mA) meter indication during AM
operation or destruction of the Final Amplifier tubes
may result.
– 11
CAUTION
On the 160 meter band, maximum platé current
should be kept within 140mA to avoid spurious
radiation when it is operated on the frequencies between 1820 KHz and 1900 KHz.