Heathkit Service Bulletins - SB-101 (Complete to 1989)
Joseph W Lutz
joelutz at JUNO.COM
Thu Apr 2 19:14:22 EST 1998
June 12, 1967
SB-101
Bulletin No:
SSB Transceiver
SB-101-1D
Driver Oscillates on 40 Meters
Remove C-924 [.02 disc capacitor] from across 150K ohm resistor & delete
from circuit.
------------------------------------------------------------------------------------------------------------------
November 1, 1967
SB-101
Bulletin No:
SSB Transceiver
SB-101-2D
Switch Action
Improvement
DELETE: (2) 253-67 (2) WASHER, .186OD, .054 THICK (1 EA FOR 100-445)
ADD: (2) C253-67 (1) " " " "
" (FOR 100-445)
ADD: (2) B255-79 (1)SPACER, 1/8 SHOULDER, THREADED
ADD: (2) A263-7 (1)FOOT, FELT, 1/8" THICK
DELETE:(4) 266-91 (1)ACTUATOR, SLIDE SWITCH
ADD: (4) 266-97 (1) " " " "
-----------------------------------------------------------------------------------------------------------------
NOVEMBER 1, 1967
SB-101
Bulletin No:
SSB Transceiver
SB-101-3D
Improper Tuning
Delete: [2] 26-109 [2] Variable Capacitor, 2 Sect. P.C. Mtg
Add: [2] 27-122 [2] Variable Capacitor, 2 Sect. P.C. Mtg
Delete: [4] 85-131-1 [1] PC Board, RF Driver Mixer [85-131
Screened 605-1225]
Add: [4] 85-131-2 [1] PC Board, RF Driver Mixer [85-131 Screened
605-1616]
Reason for change: To correct tuning trouble.
-------------------------------------------------------------------------------------------------------------------
APRIL 18, 1968
SB-101
Bulletin No:
SSB Transceiver
SB-101-4D
Improper Tuning on 40
Meters
Description of Change:
DELETE: (2) B21-31 (50) CAPACITOR, DISC .02 MFD Z5U
ADD : (2) B21-31 (49) " " "
" "
DELETE: (4) 85-131-1 (1) PC BOARD, RF DRIVER MIXER
ADD : (4) 85-131-1 (1) " " "
"
REMOVE: C-424 installed across R-401
NOTE: SBM-100-1 called for the installation of this capacitor on SB-100
units. This capacitor should now be removed.
--------------------------------------------------------------------------------------------------------------------
June 3, 1968
SB-101
Bulletin No:
SSB Tranceiver
SB-101-5D
Grounding Problems on Tranceivers
A quality of factory wired transceivers have been shipped with loose
rivets both at the rear phono sockets & at the final tube sockets.
This is causing a serious grounding problem. Corrective recommendations
are shown on the attached sheet:
[[[[[[[[[[[[[NOTE: IF MY INTERPRETATION IS NOT CLEAR - PSE LET ME
KNOW]]]]]]]]]
Illustration shows the installation of a ground buss for the rear panel
phono sockets. It also states that if the final tube socket rivets are
loose, they should be drilled out & eplaced with 6-32 hardware.
-------------------------------------------------------------------------------------------------------------------
November 25,
1970
SB-101
Bulletin No:
SSB Transceiver
SB-101-1
Meter
Zeroing
Original 10-147 control tolerance not sufficient to allow zeroing in all
units. This part is being respecified to a closer tolerance. In the
meantime, any field problems requarding zeroing of the meter can be
corrected as follows:
Change: R-107 from 100K Ohm to 82K Ohm (1-159).
-------------------------------------------------------------------------------------------------------------------
September 14, 1972
SB-101
Bulletin No:
SSB Transceiver
SB-101-2
Repeated Heterodyne Oscillator Failure
Change: R-212 from 220 Ohm to 330 Ohm 1/2 Watt resister (1-4).
------------------------------------------------------------------------------------------------------------------
May 23, 1974
SB-101
Bulletin No:
SSB Transceiver
SB-101-3
SB & HW Series Audio Amplifier & VOX
Circuit Trouble Shooting Guide
It is assumed that the basic steps such as making DC voltage measurement,
checking tubes & reviewing the soldering have been completed.
The following information was compiled from the above transceivers in the
80M LSB position. The mike level control was at the 9:00 o'clock
poisition.
AC signal voltages are listed below. These voltages were measured from
the microphone connector through the VOX circuit. All measurements were
made with a VTVM. A microphone or audio generator for .1V @ 1KHZ can be
used as the signal source.
Mike Connector Lug 1
.1VAC
Pin 2 of V1 .02VAC
Pin 6 of V1 10-15VAC
Pin 6 Level Control 10-15VAC
Pin 5 Level Control .5VAC
Pin 9 of V1 .2VAC
Pin 8 of V1 .1 - .3VAC
Center Arm of VOX Sensitivity Control 5-15VAC
Pin 7 of V17 5-10VAC
Pin 6 of V17 40-50VAC
Junction of C211-D201 40-50VAC
Pin 9 of V12 9-15VAC
By tracing the AC signal from stage to stage the point of trouble can be
isolated & steps taken to correct it.
POSSIBLE TROUBLE AREAS
- Check each of the shielded cables for a possible open or poorly
grounded shield.
- Check for continuity through each of the shielded cables.
- Check for a proper ground at the mike control level.
- If the frequency response of the audio stage is not within
specifications check the values & installation of C1, C2, C3 & C9.
- A change in VOX delay after operating for a period of time can be
caused by leakage in diode D201. The other possibility is a change in
value of capacitor C213. Either component could experience a change in
operation characteristics due to heat.
------------------------------------------------------------------------------------------------------------------
May 23, 1974
SB-101
Bulletin No:
SSB Transceiver
SB-101-4
Diode Leakage in The SB-100, SB-101, HW-101
The silicon diodes used in the SB100 & SB101 are standard power diodes
rated at 500PIV & 750MA. For each condition described, the diodes should
be replaced with an equal value to maintain proper opration.
1. Diodes D902 & D903, when leaky, will have an effect on ALC
indication. The ALC indication will be normal for the first half hour to
an hour. Then the meter indication will start dropping off until there
is very little indication.
2. D101, when leaky or defective, will cause slow or no receiver
recovery after transmitting for any period of time.
3. D905, under leaky conditions, will cause very slow or no receiver
recovery and false meter indications. The meter will kick up scale &
slowly drift down to zero.
4. D201 will result in a decrease in VOX sensitivity to the point where
the VOX circuit will not be activated. It can also result in increasing
VOX delay, causing the relay to stay in the transmit condition.
-------------------------------------------------------------------------------------------------------------------
May 23, 1974
SB-101
Bulletin No:
SSB Transceiver
SB-101-5
SB & HW Series Instability & Corrective
Information
Instability -- Trouble
shooting
We suggest you check for each of the following possible causes:
1. Intermittent, rosin or cold solder joints.
2. Loose hardware at the tube sockets, terminal strips, circuit boards,
shields and rear panel sockets.
3. Poor lead dress at tube sockets V8 & V9. The component leads must be
short as possible.
4. Check C925 (Final tune capacitor) to be sure it is isolated from the
tuning shaft. This is to prevent RF from traveling on the shaft to
the front panel.
5. Check all edges of the final enclosures for proper grounding to the
main chassis.
6. Check the hardware for the side rails to be sure a good ground is
being provided.
7. Be sure that all the ground clips on the coil cover are making good
contact with the switch shields.
8. Check the soldering of the switch shields to the center pins of tube
sockets V6, V7, V10 & V11.
9. Check the ground leads from the switch board & shields, to be sure
they are going to ground foil & not to the preselector
capacitor foil pods on the RF driver board.
10. Check for broken or shorted pigtails on each of the shielded cables
in the unit.
11. Check RFC801 & L901 for any signs of deterioration or physical
damage, (burn spots). If apparent replace the part.
12. Improper adjustment of the Het. Osc. coils could cause improper
mixing
action, resulting in the final operating at a different frequency
appearing as instability.
13. Change driver & final tubes then reneutralize per manual
instructions.
14. Check driver tube shield to be sure that it has a good ground
contact with the socket spring clip.
15. Check for a good ground between the front panel & chassis.
16. Check the SWR of the antenna system at the frequency of operation.
Should be below 2:1.
17. Check the antenna coax for leakage, poor connectors & broken shield
connections.
18. Is the transmitter properly grounded?
19. Be sure all shields & tube shields are installed.
20. Realign using a properly terminated 50 ohm non-reactive dummy load.
NOTE: This does not include a light bulb.
21. Check for normal Het. Osc. test-point voltage.
22. Check for proper LMO injection voltage 1.0-1.5 VRF.
23. Check for a high AC ripple content in the LV-B+, HV-B+ and bias
voltages from the power supply.
24. Check to be sure that the shafts do not touch each other in the
insulated
coupling, and that the set screws do not touch the PA shield.
25. Check to be sure that the PA tune shaft turns the variable capacitor
& is not slipping in the insulated coupling.
--------------------------------------------------------------------------------------------------------------------
May 23, 1974
SB-101
Bulletin No.
SSB Transceiver
SB-101-6
Alternate Method of Neutralizing The Final
Amplifiers
1. Disconect final plates & screen grid.***
2. Turn unit on.
3. Rotate the BAND switch to 28.5.
4. Place the VTVM RF probe in the ANTENNA connector.**
5. Set the FUNCTION switch to TUNE.
6. Rotate the LEVEL control fully clockwise.
7. Adjust the PRESELECTOR control for a maximum reading on the VTVM.
8. Adjust the FINAL control for a maximum indication on the VTVM, with
the LOAD control set at the 50 ohm position.
9. Using an insulated screwdriver, adjust neutralizing capacitor for a
MINIMUM indication on the VTVM.
10. Readjust the neutralizing capacitor for a minimum indication on the
VTVM.
11. Turn the FUNCTION switch to the off position.
12. Discharge high voltage power supply capacitors.
13. Reconnect final plates & screen grid.
**VTVM & RF probe will be needed.
***To remove screen voltage in SB-100, SB-101, HW-100 & HW-101 disconnect
R920 (100 ohm resistor) from buss wire between pins of V8 & V9. In the
SB-102 removal of accessory plug is all that's required. To remove high
voltage in SB-100, SB-101 & SB-102 disconnect red wire at lug 4 (in
Sb-100 lug 3) of terminal strip BK that goes to grommet BL. In HW100 &
HW101 disconnect red wire going to lug 1 of RF choke in final cage.
NOTE: Take adequate steps to eliminate any possible contact with B+ or
B+ shorts to chassis after disconnecting wire & resistor.
--------------------------------------------------------------------------------------------------------------------
December 18, 1974
SB-101
Bulletin No.
SSB Transceiver
SB-101-7
Oscillations or Low Drive
Loose boards cause sporatic self oscillations & unstable RF conditions,
particularly at the high [15 & 10 meter] bands. The comb brackets which
ahve been used are aluminum & could not be soldered. Steel brackets are
now available [Part No: 204-2096] & should be used whenever encountered
in the field. Both the switch shields & the driver boards should be
soldered to these brackets.
This change helps to increase grid drive as well as increase stability.
--------------------------------------------------------------------------------------------------------------------
May 2, 1975
SB-101
Bulletin No.
SSB Transceiver SB-101-8
Self Oscillations Occurring After Installation
of Steel Comb Brackets
It has been found that in a number of units, self oscillations are still
occurring after installation of both sets of comb brackets [Part No:
204-2096]. To correct the condition, the screws around the RF driver
board must be tightened securely. Also, the lockwashers between the
circuit board & chassis must be installed, otherwise a good ground is not
assured. Retightening screws which are already snug will also cause
these oscillations to disappear in units where it is a problem.
--------------------------------------------------------------------------------------------------------------------
March 29, 1976
SB-101
Bulletin No:
SSB Transceiver
SB-101-9
S-Meter Drift
To bring the meter drift to an acceptable level, install the following:
CHANGE: R107 from 100K Ohm 1/2 Watt to 100K 1 Watt
[PN 1-28-1]
This makes the voltage divider string more stable with temperature
changes caused by internal heating.
This change will be made in future production runs.
------------------------------------------------------------------------------------------------------------------
November 15, 1976
SB-101
Bulletin No:
SSB Transceiver
SB-101-10
Low Receiver Sensistivity
Note: Sensitivity of the unit is worse on the higher frequencies [15] &
[10] meters.
Cure: Diode D907 may be in backwards or banded backwards.
------------------------------------------------------------------------------------------------------------------
September 27, 1977
SB-101 Bulletin No:
SSB Transceiver SB-101-11
Transceiver Oscillates in Transmit with Mic Keyed
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
February 22, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-12
Tuning Erratic
Some of the earlier LMOS can be opened up for service, such as cleaning
the wiper contacts on the tuning cap when tuning becomes erratic. Some
of these units have fiber washers between the frame of the tuning
capacitor and the worm gear assembly. Intermittant contact between the
teeth of the gears can change the ground path for the tuning cap and also
cause erratic tuning. Simply replacing a fiber washer with a metal
washer will give good connection between the tuning cap frame and the
worm gear assembly to eliminate this problem.
------------------------------------------------------------------------------------------------------------------
June 5, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-13
Relays Remain Energized After Transmit Condition
After keying the transceiver with PTT for thirty to forty seconds, a
positive voltage in excess of 10 volts appears at the control grid, pin 9
of V12, thus keeping the relays energized.
To correct the problem, replace V12 [PN 411-124]. IEC brand tubes have
been found defective in several cases, but other brands may also cause
this problem.
------------------------------------------------------------------------------------------------------------------
June 5, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-14
Poor AGC Action
Leakage in the 6HS6 [PN 411-247] at V10 and/or V11 has been found to
cause:
- Poor AGC action
- Fast S-Meter decay,
- Poor sensitivity when RF gain control is fully
clockwise.
This usually occurs after warmup of at least an hour. A positive
voltage, usually over 1 volt, will appear at the grid, pin 1 of either
one or both tubes.
Replacement of the tube with the positive voltage corrects the problem.
------------------------------------------------------------------------------------------------------------------
June 5, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-15
100KHZ Calibrator Spurs
Strong signals may occur at other than 100 KHZ points.
Look at the calibrator output [ahead of output diode] with an
oscilloscope. Use high input gain and a slow sweep speed. If the upper
portion of the sine-wave signal appears choppy or uneven, the Y201
crystal may be at fault.
After installation of a new crystal [PN 404-43], recheck with an
oscilloscope.
--------------------------------------------------------------------------------------------------------------------
July 24, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-16
LMO Drift; Intermittent Frequency Shift
Check for a dirty or corroded phono connector on the rear of the LMO.
CLean if necessary.
-------------------------------------------------------------------------------------------------------------------
July 24, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-17
Poor Preselector Tracking
This problem is more noticeable on the 10-meter band. It may be caused
by the drive belt slipping or by one of the variable capacitors not
turning due to excessive friction in its bearings.
Check the belt for being loose or worn and replace as needed. Lubricate
the bearing of the variable capacitors.
If lubricating the capacitor bearings does not allow the rotor to turn
freely, replace the capacitor [PN 26-122].
-------------------------------------------------------------------------------------------------------------------
July 24, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-18
Carrier Nulls With IC14 Trimmer Plates Completely Meshed
If C14 nulls the carrier with its plates fully meshed toward V2 [to the
right], relocate C18, 12pf capacitor, to the other section of the null
trimmer [C14].
-------------------------------------------------------------------------------------------------------------------
August 7, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-19
Relays Chatter In VOX Mode
This may occur when the VOX gain is in the near-full CW position with the
MIC level advanced past the 12 o'clock position. Also, the unit will not
return to receive when the operator stops talking.
Check the tube at V1. A "GE" tube will tend to oscillate, thus causing
the above problem. Other 6EA8 tube brands should operate properly at V1.
See Bulletin No: HW-100-15 Dated August 3, 1978
------------------------------------------------------------------------------------------------------------------
August 7, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-20
Loading Capacitor Turns As Plate Capacitor Is Rotated
This problem can be caused by:
- Insufficient friction in the loading capacitor or;
- Excessive friction between the plate and load tuning shafts.
If the problem persists after freeing and lubricating the shafts, install
a rubber grommet [PN 73-3] on the loading capacitor shaft between the
pulley and the RF cage. Apply slight pressure to the grommet as the
pulley set-screw is tighted. This will add enough friction to keep the
loading capacitor still while tuning the plate control. Use only as
needed.
-------------------------------------------------------------------------------------------------------------------
August 7, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-21
"Chirping" And Slow Receiver Recovery
If "chirping" of the audio in the receive mode and slow recovery of the
receiver after long periods of transmitting are encountered, remove the
cover of RL2 and check for carbon buildup at the base, just below the
contact. Clean dirt or carbon tracks, or replace if necessary.
A dirt or carbon buildup will cause the +300 volts to be applied to
adjacent contacts such as the bias or AGC lines, adversely affecting
receiver cutoff by upsetting the operation of 1] V12, receiver mixer; 2]
V10, RF amplifier; and 3]V11, first receiver mixer.
-------------------------------------------------------------------------------------------------------------------
August 22, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-22
S-Meter Drift
If the S meter drops below zero and pins after 1/2 hour of operation,
there may be leakage in one or more of the following tubes: V3, V4, V10
or V11. New RCA tubes may exhibit the same problem. The following
procedure will aid in finding the leaky tube:
1. Disconnect R415 to isolate V3 and V4 from the AGC line.
Monitor the control grid at P1 of V3 for several minutes. If the voltage
drifts in the positive [+] direction, V3 or V4 is leaky. Proceed to step
2. If the voltage remains stable, go to step 5.
2. Remove the white/blue wire from pin 2 of T102 and repeat the
test. This will isolate V4 from V3. If the voltage still drifts, V3 is
at fault.
3. To verify, reconnect the white/blue wire and then disconnect
R101. Monitor the voltage at pin 1 of V4. The voltage should remain
stable.
4. Reconnect R415 and R101.
5. Disconnect R408 and check the voltage at pin 1 of V10. If
voltage drifts, replace V10. If the voltage is stable, replace V11.
6. Reconnect R415 and R408.
Straight substitution with new tubes may not work if more than one tube
is causing the problem, since even a small leakage can cause the drift.
When you replace a tube, check for stable voltage at its control grid.
Replace with the tube which gives most stable voltage.
--------------------------------------------------------------------------------------------------------------------
September 26, 1978
SB-101
Bulletin No:
SSB Transceiver
SB-101-23
Poor IF Sensitivity
Check C101. It may have inadvertently been wired to point 2. It should
be wired to point 15. It is an "easy-to-overlook" wiring error that
would cause the transceiver to have low if sensitivity which would result
in poor receiver sensitivity and low power output.
-------------------------------------------------------------------------------------------------------------------
April 25, 1979
SB-101
Bulletin No:
SSB Transceiver
SB-101-24
Low Power Output; Poor Vox Sensitivity
It has been determined that Sylvania, RCA and Westinghouse brand tubes do
not function properly at locations V3 and V4.
The brands found to work at these locations are: El-Menco, IEC, General
Electric and Realistic.
Westinghouse tubes at other locations throughout the unit may cause low
power output and VOX problems. It is suggested not to use Westinghouse
tubes at all.
-----------------------------------------------------------------------------------------------------------------
September 20, 1979
SB-101
Bulletin No:
SSB Transceiver
SB-101-25
Low Transmitter Output; Low Receiver
Sensitivity
When cleaning the unit during prework [tube sockets, potentiometers,
etc.], don"t overlook the SSB/CW filter slide switch located with the RF
gain control. This switch handles both transmit and receive signals and
dirt and grease build-up can affect the performance of both functions.
--------------------------------------------------------------------------------------------------------------------
January 21, 1980
SB-101 Bulletin No:
SSB Transceiver SB-101-26
Low Grid Drive on Certain Portions of One or More Bands
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
April 10, 1980
SB-101 Bulletin No:
SSB Transceiver SB-101-27
Germanium Diode Change
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
December 17, 1980
SB-101 Bulletin No:
SSB Transceiver SB-101-28
VOX Oscillation
+ + + + Information not yet available + + + +
--------------------------------------------------------------------------------------------------------------------
That's all that is listed for the SB-101 up to 1989. Enjoy!
73 de Joe W7LPF/4 [NNN0KUU]
QWCA - SOWP - NCVA - FISTS - RCC
Gordonsville, Va 22942 [Orange Co]
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