These pages will contain selected information on modifications for military, commercial and kit transmitters and receivers. If anyone has anything they would like to post here, please let me know.

Heathkit HW-100/101 and SB-100/101/101W/102.

• SBM-102-1. This is the modification to all the above transceivers to eliminate the "Miller Effect". This is what causes the driver and preselector tuning to appear at different places in the control's range. There are 9 PDF files here: the first one is the entire mod in one PDF. The other 8 are each page separately. 1) SBM-102-1.PDF, OR 2) SBM-101-11, 3) SBM-102-12, 4) SBM-102-13, 5) SBM-102-14, 6) SBM-102-15, 7) SBM-102-16, 8) SBM-102-17, 9) SBM-102-18
• A collection of Heathkit Service Bulletins for the HW-100/101.
• Another collection of Heathkit Service Bulletins for the SB/HW series
• Optimizing the HW-101. The data contained here applies equally well to the SB-100/101/102.
• A collection of HW-101 tips, compiled by a service tech from Heathkit.

  Heathkit Crystal Filter modification information.

• How to modify Heathkit SB/HW crystal filters for any bandwidth. This PDF report is especially useful for those who want an AM filter for any of their Heathkit SB series receivers.
• How to test crystal filters. The K1KP method. A PDF file.

  R-390/R-390A Rectifier tube modification.

• This completely reversible modification replaces the very difficult to find 26Z5W tubes with the much easier to find and cheaper 12BW4s, which also provide a higher dissipation rating and radiate less heat than the 26Z5Ws. Home