May 18, 1984 HD-1418 Bulletin No: Active Audio Filter HD-1418-1 Parts List Correction - S1 and S2 In manual [PN 595-2980], page 8, and HD-1418 Blue Book, page 96, correct the parts list as follows: S1 pushbutton switch from [PN 64-919] to [PN 64-920]. S2/3/4/5 four-section pushbutton switch from [PN 64-920] to [PN 64-919] ------------------------------------------------------------------------------------------------------------------- February 24, 1989 HD-1418 Bulletin No: Active Audio Filter HD-1418-2 Unit Doesn't Operate After Assembly [[[[[[[[[[[[[[[[See Bulletin No: HD-1418-3]]]]]]]]]]]]]]]]]]]]]]]] -------------------------------------------------------------------------------------------------------------------- August 31, 1989 HD-1418 Bulletin No: Active Audio Filter HD-1418-3 Unit Oscillates With PN 443-733 IC Installed In earlier production of the HD-1418 Audio Filter, the Signetic brand of MC1458 IC at U2-U12 and U15-U17 would cause the unit to oscillate. To correct this problem, these ICs were then changed to LM358 ICs [PN 442-733]. Factory Service found that the PN 442-733 ICs also caused the Filter to oscillate. To correct the oscillation problem, the following change is made: Change: U2-12 and U15-U17 from LM358 IC [PN 442-733] to a TI brand MC1458 IC [PN 442-839]. QA found the oscillation occurs in U7 and U11 when an IC other than a TI brand ICs are installed. Either a TI brand of PN 442-21 or a PN 442-839 can be used as a replacement part. This bulletin supercedes HD-1418-2. -------------------------------------------------------------------------------------------------------------------- Thats everything I hold up to 1989 that covers the HD-1418. Enjoy! -------------------------------------------------------------------------------------------------------------------- 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va 22942 [Orange Co]