------------------------------------------------------------------------------------------------------------------
					April 4, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-61

			                         R-907 Overheats

During extended periods of operation in the low power mode, R-907 may
overheat.

Change:  R-907 to a 1K ohm resistor [PN 1-9].
--------------------------------------------------------------------------------------------------------------------
					April 4, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-62

		                                  Broadcast Interference

When operating near strong AM broadcast stations, D-904 will rectify the
signal, causing annoying interference.  To remedy:

	Add 4.7K ohm resistor [PN 1-8-12] across C-907, thus reverse-biasing D-904
in the receive mode.

Implement this change only as needed.
-----------------------------------------------------------------------------------------------------------------
					April 17, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-63

	                           ALC/Filter Board Phono Connectors Shorting to the Shield

Due to the proximity of the shield [PN 206-1265] to the circuit board, the
possibility of the connectors shorting to the shield exists.

To prevent this, install a piece of fish paper [PN 75-108] on the shield
directly behind the connectors.

Be sure the proper phono plugs [PN 438-46] are used on the cables.
--------------------------------------------------------------------------------------------------------------------
					April 21, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-64

		                              Increased ALC Meter Action

C-827 on the ALC/Filter (K) circuit board should be changed to a .68 uf
tantalum capacitor [PN 25-200].

This change will increase attack time on the ALC loop and decrease the
possibility of "flat-topping."

This will be incorporated in future production lots.
---------------------------------------------------------------------------------------------------------------------
					May 24, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-65

		                             Low Or Erratic ALC Action

Relocate diode D7 from across meter terminals to switch S2C, lug 2 to
ground.  The cathode is connected to ground.
----------------------------------------------------------------------------------------------------------------
					May 24, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-66

		                        40 Meter Not Linear Through Band

Replace C-341 with a 470 pF mica capacitor [PN 20-113].  This will broaden
response and reduce the sharpness of the roll-off.
------------------------------------------------------------------------------------------------------------------
					May 24, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-67

		                                  Reduction Of Talk Back

The following steps should be taken in units received for servicing because
of a "talk-back" problem:

CHASSIS WIRING CHANGES

- Move the two large orange stranded wiress from J1 to F19.

- Remove and discard the small orange wiree between J1 and K3.

- Locate the small orange wire between J1  and relay lug 11.  Relocate the J1 end to K3.

- Connect a new heavy stranded wire betweeen J1 and H6.

F BOARD CHANGES

- Change R-581 to an 18M ohm resistor [PN  6-186].

- Change R-578 to an 1800 ohm resistor [PNN 6-182].

The above procedure should remedy most "talk-back" problems.  However, if a
customer isnot sufficiently placated; and only to avoid a refund; the
following procedure may be performed:

SB SERIES

- Move the gray wire from the CW switch, llug 2 to Tune switch, lug 3.

- Remove the jumper wire which is between  Tune switch, lug 3 and CW switch,
  lug 2.

- Relocate the white-violet wire from CW sswitch, lug 4 to HI switch, lug 6.

- Remove the jumper wire from between CW sswitch, lug 6 and LSB switch, lug 6.

- Relocate gray wire from CW switch, lug 66, to LSB switch, lug 6.

- Install a 100 ohm, 1/2 watt resistor [PNN 6-101] from HI switch, lug 6 to CW switch,
  lug ? ((Fiche is unreadable, but could POSSIBILITY be lug 3)).

- Locate the orange wire from F19 to relayy lug 11.  Relocate the wire end
  at relay lug 11 to relay lug 3.

- Install an orange wire from F19 to CW swwitch, lug 4.

- Install an orange wire from K3 to CW swiitch, lug 6.

- Install a 560 ohm resistor [PN 6-561] beetween F19 and ground.

HW SERIES

- Relocate the diode from between CW switcch, lug 5 and LSB switch, lug 6 to
  between USB switch, lug 6 [banded end] and USB switch, lug 1.

- Move the brown and gray wires from the CCW switch, lug 6 to the USB
  switch, lug 1.

- Move the orange wire at relay lug 11 to  relay lug 3.

- Install an orange wire between F19 and CCW switch, lug 3.

- Install an orange wire between CW switchh, lug 5 and K3.

- Install a 560 ohm, 1/2 watt resistor [PNN 6-561] between F19 and ground.
-----------------------------------------------------------------------------------------------------------------
					May 30, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-68

		                          Mounting Hole Missing At L-815

Presently, two types of ALC/Filer circuit boards [PN 85-2056-1] are being
shipped in the SB-104A transceivers.  Both types have the same part number.

When mounting L-815 [82 uH peaking coil], you will find that one board has
two mounting holes- -the other only one.  On circuit boards with only one
hole, connect the second lead of L-815 to the switch, upper lug 14.

When the circuit board with the single hole is packed in  a kit, Manual
insert [PN 591-2650] will be included, which shows proper installation
procedures.

The manual [PN 595-1992-01] shows normal 2-hole installation procedures.
-------------------------------------------------------------------------------------------------------------------
					July 24, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-69

	                           Receiver Overload With Noise Blanker Installed

Occasionally local ham stations cause receiver overload in units where the
noise blanker is installed, even when the Blanker is switched off.

To correct:

- Connect pin 6 of the Noise Blanker to grround.

- Rewire the fron panel NB switch as shownn in the schematic at the right.

((Center conductor from Board G/with outer conductor grounded, wired  to
one side of switch.  Same side - wire from switch to IN on Blanker Sw/outer
conductor grounded.  Wire from OUT on Blanker Sw/outer conductor grounded,
to opposite side on NB switch.  Other terminal of same side wire to Board
E, with the outer conductor grounded))

This wiring change will route the RF signal directly to Board E when the
switch is in the OUT position.

When the switch is in the IN position, the RF signal will go through the
Noise Blanker.
---------------------------------------------------------------------------------------------------------------------
					August 21, 1978
SB/HW-104(A)								Bulletin No:
Soild State Transceiver							SB-104-70

			                     "C" Board Information

Service Policy:  SPC servicing centers may perform standard service
procedures on circuit boards that are in or out of warranty.  Factory-built
"C" boards will be warranted for 90 days.  BE SURE THE C BOARD IS AT FAULT
BEFORE SENDING IT TO THE FACTORY FOR SERVICE.

The "C" boards are check at the factory on a special fixture for spurious
and harmonic content.  The power output is set to 100 watts, +/- 1 dB.

Resistor R-332 may be any one of the following four values: 
		1180 ohm [PN 6-1181-12]
		1200 ohm [PN 6-122-12]
		1210 ohm [PN 6-1211-12]
		1240 ohm [PN 6-1241-12]

Always replace R-332 with a resistor of the same value.  Any deviation from
the selected resistor value on the "C" board will void the warrantly on the
C board, driver board "J", power amplifier board "H" or ALC/Filter board,
"K".

C-342 has been changed to 74 pF capacitor [PN 20-110] in the -02 level.
-----------------------------------------------------------------------------------------------------------------
					August 21, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-71

		                   Shorted 11-Volt Supply; No Transmitter
			                                  Output

If the bare wire on the top of the peaking coils, L-322 and L323 on the "C"
board, is toching the shield plate between the C and B boards, it will
short out the 11-volt supply and/or destroy R-305.  To correct, install a
piece of fish paper [PN 75-108] on the shield between the C and B boards.
-------------------------------------------------------------------------------------------------------------------
					May 30, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-68

		                          Mounting Hole Missing At L-815

Presently, two types of ALC/Filer circuit boards [PN 85-2056-1] are being
shipped in the SB-104A transceivers.  Both types have the same part number.

When mounting L-815 [82 uH peaking coil], you will find that one board has
two mounting holes- -the other only one.  On circuit boards with only one
hole, connect the second lead of L-815 to the switch, upper lug 14.

When the circuit board with the single hole is packed in  a kit, Manual
insert [PN 591-2650] will be included, which shows proper installation
procedures.

The manual [PN 595-1992-01] shows normal 2-hole installation procedures.
-------------------------------------------------------------------------------------------------------------------
					August 21, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-71

		                   Shorted 11-Volt Supply; No Transmitter
			                                  Output

If the bare wire on the top of the peaking coils, L-322 and L323 on the "C"
board, is toching the shield plate between the C and B boards, it will
short out the 11-volt supply and/or destroy R-305.  To correct, install a
piece of fish paper [PN 75-108] on the shield between the C and B boards.
---------------------------------------------------------------------------------------------------------------------
					August 21, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-72

	                                      Low Transmitter Output on 10 Meters

First check to verify the performance of the Driver, PA and ALC/Filter
circuit boards,  These boards may be verified by substituting a
"known-good" C board into the unit.  All four segments of the 10 meter band
should be checked.  Proper power indicates these boards are good.

If there is proper power on 10 meters with the substituted C board, proceed
as follows:

- Reinstall the customer's C board.

-  Couple a frequency counter to the outpuut of the C board at pins 23 and 24.
   The measured frequency should be 28 to 29.7 MHz, depending on which segment 
   of the 10 meter band the unit is operating on.  It is possible the 10 meter pre-driver
   coils; L-309, L-310, L-319 and L-320 are detuned enough to give a frequency output of 32 Mhz.
   This is the sum of the premix and IF frequencies, rather than the
   difference.  The ALC/Filter board will attenuate this frequency, and thus,
  the unit will indicate low power out on the 10 meter band.

- Readjust the 10 meter coils for the propper frequency output.  Follow with manual alignment.

- Continue the recommended alignment proceedure in the manual.
-------------------------------------------------------------------------------------------------------------------
					September 26, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-73

		                                Driver Transistors Overheating

CTC devices, with a date code of BY323, at Q-901 and Q-902 [PN 417-830] on
the Driver circuit board have a tendency to overheat.  This occurs mainly in
the idle condition.  Use only CTC devices with date codes other than BY323.
-------------------------------------------------------------------------------------------------------------------
					October 12, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-74

	                        Bandpass Filter Response Check With The IG-57A
Sweep
			                                 Generator

The are times when in checking the power output of the SB-104, the power
may be low at one end or the other of a particular band.  With the
following procedure, this situation can be checked, and if necessary, the
bandpass filters can be trimmed to even out the response.

Procedure:

1.  Connect the sweep output of the IG-57A to the SB-104 VFO input.
     [Remove the VFO jumper.]

2.  Set the generator attenuator to 20 dB.

3.  Set the IG-57A to Low Sweep and adjust for wide sweep passing through the
    5.0 - 5.5 MHz range.  [This will simulate VFO tuning across the band.]

4.  Connect a signal generator tuned to 5.0 MHz and then 5.5 MHz to the IG-57A
    External Marker input.  This is to provide the marker reference.

    NOTE:  The IG-57A 4.5 MHz marker may also be used.

5.  Connect a Demodulator probe to a suitable scope and monitor at either D6,
     Q-304 [collector], C-24 or the RF output jack [LOW POWER OUTPUT ONLY].
     Check the response curves of the various bandpass filters.

     This method can quickly isolate the bandpass filter which is causing the low
     power output at one end of the band problem.

A response curve of the 20 Meter Board D bandpass filter which is skewed
low, causing low output at the high end of the band.

	5.5 MHz Marker	= 17.395 MHz at Board D
			= 14.0 MHz at Board C

	5.0 MHz Point	= 17.895 MHZ at Board D
			= 14.5 MHz at Board C
-------------------------------------------------------------------------------------------------------------------
					October 12, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-75

		                                 VOX Amplifier Oscillation

It has been noted that the VOX may key the transmitter with the VOX gain
fully CW and without a microphone connected.  This is caused by an
oscillation in the VOX amplifier.

To correct this, install a .001 uF capacitor [PN 21-140] from terminal B18
to ground.  This will suppress the oscillation in the VOX amplifier.
---------------------------------------------------------------------------------------------------------------------
					November 20, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-76

	                     Excessive 15 Meter HFO Signal At Antenna Jack In HI-Power
		    	                                       Mode

Check to see if the ground foil located on the "C" board, between Q-302 and
Q-303, is cut.  If so, reconnect the cut ground foil.  This foil should not
be cut when installing modifications in this unit.  Bulletin SB-104-54 and
SBM-104-2 had instructed the technician and customer to cut the foil on the
"C" board.  Please cross out this step in SB-104-54.  This step is also
being removed from the instructions for mod kit SBM-104-2.
---------------------------------------------------------------------------------------------------------------------
					November 28, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-77

	                       Burst Of RF On 10 Meter Band When Transmitter Is Keyed
			                            With PTT On SSB

A burst of 100 watt RF on the 10 meter band exists when the transmitter is
keyed with PTT on SSB.  This is caused by Q-601 remaining on too long due
to the long discharge time of C-608.  Thus Q-601 is still on when Q-602
turns on.  On 10 meters, a signal of approximately 3395 kHz appears to be
generated at the front end board and is amplified by the still turned on
Q-602, passes through Q-602 to the input of the transmitter IF board where
it is amplified and heterodyned to the 10 meter band.  Here it is amplified
again and passed to the driver and PA.

The solution is have Q-601 turn off before Q-602 turns on.  To do this,
remove the wire from chassis connector pin E3 to E11.  Now, connect a wire
from E3 to C7.

Since the newer SB-104A front end board [G] has higher gain, this problem
may only exist in the "A" model units, but willnot show up in all of them. 
It can show up in both high and low power and is dependent on the gain of
the various circuits involved.
---------------------------------------------------------------------------------------------------------------------
					November 28, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-78

	                                        Update Of SBM-104-2 Modification
Kit

The instructions given on page 13 of the Modification Manual [PN 595-2016-0
through -03] for cutting the ground foil on the "C" board should be deleted
when installing the PN 830-24 modification kit.

The 360 pF mica capacitors installed on page 19 of the same manual should
not be installed, especially if a clearance problem exists between the foil
side of the circuit board [PA], and the metal heat sink plate.  The -04
edition of the manual [PN 595-2016] has deleted this instruction.  If the
capacitors are already installed and no clearance problem exists, leave
them installed.
-------------------------------------------------------------------------------------------------------------------
					November 28, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-79

		                                       PA Board Oscillations
			
It has been found that the PA board oscillates at approximately 27 MHz in
high power position on all bands, including 15 MHz with the microphone gain
turned counterclockwise and in TUNE position.

This is caused by an open connection between the phone plug shield and the
coax cable shield of the power amplifier output cable.  Check for proper
connections at these points.

Also, 3.5 MHz and 7.0 MHz bands oscillate at approximately 21 MHz with the
same conditions listed above.

This is caused by open connections from the phone plug shields to the
shields of the coax cables to the ALC/Filter board.  Check for proper
connections at these points.
------------------------------------------------------------------------------------------------------------------
					December 11, 1978
SB/HW-104(A)								Bulletin No:
Solid State Transceiver							SB-104-80

	                                Burst Of RF When PTT Is Released In SSB Mode

This burst of RF when the PTT is released can occur on all bands.  Three
causes of this are:

1.  A spike on the audio output of board B caused by the +RX mute voltage
applied to pin 2 of IC201B through R212.  The solution is to let IC201B
remain active all the time.  This is done by connecting R212 to ground
instead of Q-205's collector.

2.  The rapid rise of the voltage on the PTT line.  This is coupled to the
input of IC201A through the stray capacitance at the MIC connector. 
Installing a .05 uF capacitor from B8 to ground slows the rise time enough
to prevent this coupling.

3.  The transmitter is keyed for the first time after power is first
applied to the unit.  The application of power to the unit causes a charge
to build up on C-646 which, in turn, causes a short burst of carrier output
when the balanced modulator is driven with a signal from the carrier
oscillator.  Subsequent keying will not produce the burst.  Installing a
6.8K ohm resistor [PN 6-682-12] across C-646 will allow it to discharge. 
Then perform the carrier null adjustments.

To prevent the RF burst, make the following changes:

- Remove the jumper connecting R-212 to Q--205 collector.  Connect R-212 to ground.

- Install a .05 uF capacitor [PN 21-143] ffrom B8 to ground.

- Install a 6.8K resistor [PN 6-682-12] accross C-646.
---------------------------------------------------------------------------------------------------------------------
					March 20, 1979
SB-104A								Bulletin No:
Solid State Transceiver							SB-104-81

			                          Q-603 Oscillates

If the circuit of Q-603 oscillates, it may be caused by a too-high input
impedance of some of the PN 417-274 FETs at Q-501 on the Receiver IF
circuit board.  This problem is apparent when the AGC is off and the RF
gain is varied.  To correct the problem, replace Q-501 [PN 417-274].
---------------------------------------------------------------------------------------------------------------------
					September 20, 1979
SB-104A								Bulletin No:
Solid State Transceiver							SB-104-83

	                     21 MHz Bandpass Filters On TX IF Difficult To Bring
                             To Specs On Edges Of Band

Change C-356 to 5 pF ceramic disc capacitor [PN 21-78].  This will broaden
the response on the bandpass filters before the redrivers.  It will also
reduce the spurious compoonents on the output.

Make this change on an "as-needed" basis only.
--------------------------------------------------------------------------------------------------------------------
					November 19, 1979
SB-104A								Bulletin No:
Solid State Transceiver							SB-104-84

	                              Obtaining A more Logarithmic S-Meter Response

The S-meter in most units is largely insensitive to plainly audible
signals, while allowing slightly louder signals to peg the meter [with
R-534 set for an S9 meter reading at 50 microvolt signal at the antenna
connector].  To provide a more logarithmic response, perform the following:

- Replace ZD-502 with a 1N191 signal diodee [PN 56-26].  Install this diode
  opposite that shown on the circuit board, so that it is forward-biased
  [cathode towards R-534].

- Set R-534 to S9 with a 30 microvolt signnal.

The meter will register slightly more accurately from S9 to +30 but will
have little or no action above +40.
	
Perform this modification only if the customer specifically complains of
this problem.
