Heathkit service Bulletins - SB-101 (Complete)

Joseph W Lutz joelutz at JUNO.COM
Mon Jul 21 21:21:47 EDT 1997

                                                         May 23,
1974SB-100               Diode leakage in the SB-100, SB-101, HW-100
     Bulletin No:SSB Transceiver
                                                   SB-100-1The 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
                                                         May 23,
1974SB-100                      Alternate Method of Neutralizing The
Final       Bulletin No:SSB Transceiver
Amplifiers                                             SB-100-21.
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 removeal 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 &
                                                          May 23,
                                         Bulletin No:SSB Transceiver

       SB-100-3                                      SB & HW Series Audio
Preamplifier & VOX                                                Circuit
Trouble Shooting GuideIt 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
                .1VACPin 2 of
V1                                      .02VACPin 6 of
V1                                      10-15VACPin 6 Level
Control                                 10-15VACPin 5 Level
Control                                 .5VACPin 9 of
V1                                      .2VACPin 8 of
V1                                      .1 - .3VACCenter Arm of VOX
Sensitivity Control                     5-15VACPin 7 of
V17                                     5-10VACPin 6 of
V17                                     40-50VACJunction of
C211-D201                               40-50VACPin 9 of
V12                                     9-15VACBy 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
                                                           May 23,
1974SB-100                                              Bulletin No:SSB
Transceiver                                     SB-100-4
                               Instability  -  Trouble ShootingSEE
                                                           December 18,
1974SB-100                                              Bulletin No:SSB
Transceiver                                     SB-100-5
                                         Oscillations or Low DriveLoose
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
                                                         May 2,
1975SB-100                                              Bulletin No:SSB
Transceiver                                     SB-100-6
                         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 settl comb brackets [Part No:
204-2096].  To correct the condition, the screws around the RF driver
board must be tightened securely.  Also, the lockwarsers 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-100                                          Bulletin No:
SSB Transceiver                                 SB-100-7

                                S-Meter Drift

See Bulletin No: HW-101-10 Dated March 26, 1976
                        February 22,
1978SB-100                                              Bulletin No:SSB
Transceiver                                     SB-100-09                       Tuning
ErraticSome 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, 1978SB-100                                           Bulletin
Transceiver                                     SB-100-10       Relays
Remain Energized After Transmit ConditionSee Bulletin No:  HW-100-9 Dated
June 5,
1978------------------------------------------------------------------------------------------------------------------                  June
5, 1978SB-100                                           Bulletin
Transceiver                                     SB-100-11                       Poor
AGC ActionSee Bulletin No:  HW-100-10 Dated June 5,
1978-------------------------------------------------------------------------------------------------------------------                 June
5, 1978SB-100                                           Bulletin
Transceiver                                     SB-100-12
      100KHZ Calibrator SpursSee Bulletin No: HW-100-11 Dated June 5,
1978-------------------------------------------------------------------------------------------------------------------                 July
24, 1978SB-100                                          Bulletin
Transceiver                                     SB-100-13
    LMO Drift; Intermittent Frequency ShiftCheck for a dirty or corroded
phono connector on the rear of the LMO.  CLean if
necessary.----------------------------------------------------------------------------------------------------------------                      July
24, 1978SB-100                                          Bulletin
Transceiver                                     SB-100-14
       Poor Preselector TrackingSee Bulletin No:  HW-100-13 Dated July
1978----------------------------------------------------------------------------------------------------------------                    July
24, 1978SB-100                                          Bulletin
No:SSB Transceiver                                      SB-100-15
 Carrier Nulls With IC14 Trimmer Plates Completely MeshedSee Bulletin No:
HW-100-14 Dated July 24,
1978-----------------------------------------------------------------------------------------------------------------                   August
7, 1978SB-100                                           Bulletin
Transceiver                                     SB-100-16
 Relays Chatter In VOX ModeSee Buleltin No:  HW-100-15 Dated August 7,
1978------------------------------------------------------------------------------------------------------------------                  August
7, 1978SB-100                                           Bulletin
Transceiver                                     SB-100-17       Loading
Capacitor Turns As Plate Capacitor Is RotatedSee Bulletin No:  HW-100-16
Dated August 7,
1978------------------------------------------------------------------------------------------------------------------                  August
7, 1978SB-100                                           Bulletin
No:SSB Transceiver                                      SB-100-18
           "Chirping" and Slow Receiver RecoverySee Bulletin No:
HW-101-32  Dated August 3,
1978-------------------------------------------------------------------------------------------------------------------                 August
22, 1978SB-100                                          Bulletin
Transceiver                                     SB-100-19                       S-Meter
DriftSee Bulletin No: HW-100-17 Dated August 22,
1978--------------------------------------------------------------------------------------------------------------------                        September
26, 1978SB-100                                          Bulletin
Transceiver                                     SB-100-20                       Poor
IF SensitivitySee Bulletin No:  HW-100-19 Dated September 26,
1978.--------------------------------------------------------------------------------------------------------------------                       April
25, 1979
SB-100                                          Bulletin No:
SSB Transceiver                                 SB-100-21

            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.

That's it for SB-100.  Bulletin No: 8 is missing due to in being issued
in 1977.

73 de JOE- - - - - - - - - - -W7LPF/4 (NNN0KUU)- - - - - - - - - - - - -
- -QWCA - NCVA - SOWP - FISTSGordonsville, Va 22942 (Orange
County)Looking for:  Heathkit HR/HX-20, MR/MT-1,
Central Electronics 100V or 200V- - - - - - - - - - - - - - - - - - - - -
- - - - - - - - - - - - -

More information about the Boatanchors mailing list