February 18, 1975 SB-230 Bulletin No: Linear Amplifier SB-230-1 Power Reduction When Reactivated on 10 Meters After the linear has been loaded up on 10 meters and allowed to cool for three minutes, the power might only go up to 200 watts output when reactivated. After a few seconds [A1 emission key down] the output will jump up to a normal 550 watts. Remove the wire from between the rf choke and coupling capacitor C11 and connect a 14 guage bare wire between the solder lug on C11 and the solder lug on top of the tube plate cap. -------------------------------------------------------------------------------------------------------------------- August 15, 1975 SB-230 Bulletin No: Linear Amplifier SB-230-2 New Type Delay Tube Socket A newer type delay tube socket was just procured, using the same part number [436-56], will have to be mounted from the bottom side of the chassis, which is contrary to the manual instruction. The manual will be inserted. ------------------------------------------------------------------------------------------------------------------ September 30, 1976 SB-230 Bulletin No: Linear Amplifier SB-230-3 Replacing Grid Bypass Capacitors Replacing gid bypass capacitors can be made much easier by following these steps: 1. Remove the tube clamp. 2. Remove solder from the capacitor mounting hole, using a desoldering tool. 3. Clip the old capacitor lead, and unscrew and remove the old capacitor. 4. Clip a slot in the upper ring of the grid ring capacitor mounting hole, and bend as shown below. 5. Follow the manual instructions for shaping the new capacitor. 6. Install the new capacitor in the chassis, secure in place, and put the capacitor lead in the slot in the ring. 7. Bend ring back to shape and solder. -------------------------------------------------------------------------------------------------------------------- September 30, 1976 SB-230 Bulletin No: Linear Amplifier SB-230-4 Improperly Installed Grid Ring The grid ring on the #8873 power tube should be checked for proper installation before power is applied to the linear. The grid ring may be improperly installed on the ceramic portion of the tube, and either touches the plate, or allows high voltage to arc over and destroy the switching diode D17 across the relay. The power supply diode stack and the PA tube itself, can be easily destroyed. The grid ring should be installed low enough on the tube to prevent touching or arching of the high voltage, but not so low that it touches the metal rivets holding the tube socket. ---------------------------------------------------------------------------------------------------------------- October 18, 1976 SB-230 Bulletin No: Linear Amplifier SB-230-5 6KV Coupling Capacitor Cannot Be Mounted On Tuning Capacitor The [PN 26-144] tuning capacitor has a 6-32 threaded shaft on the upper left rear end [when viewed from the rear of the capacitor] used to mount the .001 UF, 6KV [PN 21-165] output capacitor (Refer to P. 47, pictorial 15 of the assembly manual). Some SB-230's have been shipped with the stud on the opposite side, leading to incorrect installation of the 10 meter coil if customers attempt to assemble the unit with the defective capacitor. The defective [PN 26-144's] should be replaced with capacitors having the stud on the correct side. ------------------------------------------------------------------------------------------------------------------- September 26, 1978 SB-230 Bulletin No: Linear Amplifier SB-230-6 Meter Scale Not Illuminated A recent shipment of SB-230 amplifiers, series #05802, has been noted to have a defective meter [PN 407-185]. The meter scale information was put on metal rather than clear plastic. As a result, the pilot light will not shine through to illuminate the meter schale. The meter operates properly, however. Replace the defective meter at no charge to the customer. ------------------------------------------------------------------------------------------------------------------- September 2, 1980 SB-230 Bulletin No: Linear Amplifier SB-230-7 RFC 5 Overheats and Circuit Breakers Trip ++++Information not available at this time++++ ------------------------------------------------------------------------------------------------------------------- April 6, 1984 SB-230 Bulletin No: Linear Amplifier SB-230-8 Interfacing The Linear To Kenwood Exciters The ALC voltage to Kenwood transceivers and transmitters should not exceed -8 volts. To Ensure the proper voltage to the Kenwood, add: An 8 volt zener diode [PN 56-621] across the ALC connector on the back of the amplifier. Connect the banded end of the diode to the ground lug. Adding a control in the ALC line (as instructed in previous bulletins) to control the level of ALC voltage doesn't always work. This control loads the ALC line so much that very little ALC voltage is developed, resulting in the exiter overdriving the linear, In units which have the control installed and the operation is still unsatisfactory, return the ALC circuit to its original design and install the zener diode. ------------------------------------------------------------------------------------------------------------------- September 12, 1986 SB-230 Bulletin No: Linear Amplifier SB-230-9 PN 64-24 Safety Interlock Switch NLA The #64-24 safety interlock switches at SW4 and SW5 are no longer available from Heath Parts Replacement. The #65-39 lever switch is an approved substitute. After installing the lever switch, bend the end of the lever slightly upward so the switch actuates whent he cover is installed. ----------------------------------------------------------------------------------------------------------------- September 12, 1986 SB-230 Bulletin No: Linear Amplifier SB-230-10 [PN 255-164] 4-40 X 5/8" Tapped Spacer NLA The 4-40 x 5/8" tapped spacer used to mount the pilot lamp bracket is no longer available from Heath Parts Replacement. Replace the spacer with a 4-40 x 11/16" tapped spacer [PN 255-814] and mount the lamp bracket with a 4-40 x 1/4" screw [PN 250-1411]. ------------------------------------------------------------------------------------------------------------------- That's everything I hold up to 1989 that covers the SB-230 . Enjoy! ------------------------------------------------------------------------------------------------------------------- 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va 22942 [Orange Co]