October 10, 1977 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-1 Calibration of Oscillator Circuit & Check-Out of Detector Circuit Operation ++++Information not yet available++++ ------------------------------------------------------------------------------------------------------------------ February 27, 1981 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-2 Low or No Meter Indication With Brown Coil Installed ++++Information not yet available++++ ------------------------------------------------------------------------------------------------------------------ July 30, 1982 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-3 Will Not Oscillate at High Frequency ++++Information not yet available++++ ----------------------------------------------------------------------------------------------------------------- January 18, 1985 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-4 Oscillator Dead On the oscillator board, check Q11 [PN 417-290] for short between collector and transistor case. The metal case on the #417-290 transistors should be isolated from the collector. Defective transistors found in Parts Replacement stock and kits in finished goods had a date code of 413. Heath Parts Replacement stock has been 100% checked. Finished goods will be inserted with good #417-290 transistors. -------------------------------------------------------------------------------------------------------------------- February 8, 1985 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-5 Unit Oscillates Without Coil Installed The circuitry of Q21 self-oscillates when no coil is installed, causing a full-scale deflection of the meter. To correct this problem, install a ferrite bead [PN 475-15] on the G1 lead of Q21. The next production of kits will have the ferrite bead and insert [PN 591-4661]. Present stock of kits will not be inserted. -------------------------------------------------------------------------------------------------------------------- July 31, 1987 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-6 5 pF, 500 Volt Capacitor [PN 21-157] NLA The 5 pF, 500 volt capacitor at C13 is no longer available from our vendors. C13 is changed to a 5 pf, 50 volt capacitor [PN 21-7621-05]. ------------------------------------------------------------------------------------------------------------------- November 28, 1988 HD-1250 Bulletin No: Solid State Dip Meter HD-1250-7 On/Off Pushbutton Knob Change Purchasing can no longer buy the original pushbutton knob. The knob is changed: From a [PN 462-1047] knob to a [PN 462-1303] knob. ------------------------------------------------------------------------------------------------------------------- Thats everything I hold up to 1989 that covers the HD-1250. Enjoy! ------------------------------------------------------------------------------------------------------------------- 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va 22942 [Orange Co]