Heathkit Service Bulletins: HW-8 (1966-89 Complete) -------------------------------------------------------------------------------- Joseph W Lutz (joelutz@JUNO.COM) Tue, 7 Apr 1998 17:25:53 -0700 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Next message: Automatic digest processor: "HEATH Digest - 7 Apr 1998 to 8 Apr 1998" Previous message: Gaetan Lavergne: "HW-5400" -------------------------------------------------------------------------------- October 28, 1975 HW-8 Bulletin No. CW Transceiver HW-8-1 Service Data Operating Characteristics 1. Receiver preselector peaking is done with the preselector (C301) FCW (Minimum C) resulting in only broad peaks or no peaks being found when this control is adjusted. Also, maximum sensitivity may not coincide with maximum noise when adjusting the preselector. For example, in trying to locate a Generator Signal, the preselector would be tuned for maximum noise. When the signal is found and the preselector adjusted for a miximum signal, the defference between the maximum noise point and the noise level at the maximum signal point could vary as much as 6 db (typical). Therefore, be sure to peak the preselector on the signal and not on the noise. 2. Internal spurious signals may be found at 3.55MHZ, 7.1MHZ & 14.1MHZ. The levels are approximately .7 to 8 uv. 3. Receiver sensitivity will increase when the selectivity switch is switched from the wide to the narrow position. This is due to the added gain of the bandpass filter IC-2B and it's associated circuity. 4. Microphonic levels as compared to the HW-7 have been reduced greatly, although some still appear on the 80 Meter band. These microphonics are noticeable at the lower and center areas of the band when more capacity is required from the preselector. 5. The receiver tends to pick up more hum on 15 Meters than on any other band. The hum levels on 15 Meters is much less than those present on the HW-7. RECEIVER CHECKS: - Sensitivity: 1uv or less for 10 db S+N/N Typical Sensitivity: 80 Meters - .5uv 40 Meters - .6uv 20 Meters - .7uv 15 Meters - .7uv - Selectivity: Wide - 750 HZ at 6 db down. Norrow - 375 HZ at 6 db down. A rough check of the wide and narrow BPF can be made by tuning the receiver to a signal so that a high-pitched beat note is heard in the wide position. Switching to the narrow position should produce a noticeable decrease in the audio output. - Dial Tracking: Within one dial division. Service Notes 1. Poor Sensitivity: Poor sensitivity can be caused by either Q1 (Part # 417-169) or IC-1 (Part # 442-96). Poor sensitivity on one band only is usually caused by Q1. 2. 15 Meter Band Adjustments: The adjustments may be more critical on the 15 meter band than on other bands. It may be necessary to set the mixer coil, check the power output & sensitivity and then reset the mixer coil. Check the high & low end of this band and adjust coil L6 to bring up the end that has the lower output. 3. Receiver Oscillates on the 80 Meter Band: When operating the transceiver at DC input voltages greater than 12.5 VDC, the receiver may oscillate at points throughout the 80 meter band. To correct this problem connect a 10 K ohm resistor (Part # 1-9-12) across the 80 meter mixer coil L13. This resistor is soldered to the coil terminals on top of the circuit board. Install this resistor only when needed. The receiver should not produce undesired oscillations - - - except at internal spurious frequencies listed in operating characteristics -- when the DC input voltage is raised to as much as 15 VDC. Final Check The following is a list of physical & functional checks that must be made before returning the transceiver to the customer: Physical Checks: - All hardware installed & tightened - Cabinet & windows clean - Plastic feet installed - Controls & switches operate smoothly - Knobs properly indexed & secure - Mark to the left of 0 on dial is aligned with black line on window. Mark stays aligned when tuning knob is turned further clockwise. - Shake test - - - nothing rattles inside. - Paperwork in order. Functional Checks: - TX power output - 1 watt or greater on all bands. Connect a 50 ohm non-reactive load to the antenna jack. Tune the dial to 150, key the transmitter and measure the RF voltage across the load. The unit is within specs if the RFV is 7V rms or greater. - Typical powr output: 80 Meters - 1.5 W 40 Meters - 1.5 W 20 Meters - 1.5 W 15 Meters - 1.5 W - TX frequency offset: Approximately 750HZ lower than the Receive frequency. Check what transmitter frequency is shifting below the receive frequency by approximately 750HZ +/- 200HZ. The amount of frequency offset does change from band to band. - Sidetone is heard in speaker or headphones when the transmitter is keyed. ---------------------------------------------------------------------------------------------------------------- April 6, 1976 HW-8 Bulletin No: CW Transceiver HW-8-2 Unit Chirps A slight chirp problem has shown up on some of the HW-8 units which are now in the field. The problem has been traced to the hetrodyne oscillator switching diodes which are apparently not isolating sufficiently in the off bands. We are therefore changing the heterodyne oscillator switching diodes D22 through D29 from PN 56-24 to PN 56-56. The 56-56 diode has less capacitance and probides better isolation. Second production lot will have the 56-56 diode. ------------------------------------------------------------------------------------------------------------------ April 29, 1976 HW-8 Bulletin No: CW Transceiver HW-8-3 VFO Alignment with Frequency Counter Using the following procedure to adjust the VFO with a frequency counter instaed of a receiver: 1. Connect the frequency counter probe through a 47 PF [approx] capacitor to the emitter of transistor Q3. Connect the counter's ground lead to the chassis. 2. Turn the HW-8 on and allow it to warm up for at least 30 minutes before you proceed. 3. Release all pushbuttons to out position. 4. Turn the HW-8 tuning dial to 0. 5. Use an insulated screwdriver and adjust C302B [on the side of the tuning capacitor] until the counter reads 8.895 MHZ. 6. Turn the HW-8 turning dial to 250. 7. Use a large plastic alignment tool and adjust the slug in coil L9 until the counter reads 8.645 MHZ. 8. Repeat steps 4 through 7 several times until the counter reads properly with no adjustment at each end of the dial. ------------------------------------------------------------------------------------------------------------------- July 13, 1976 HW-8 Bulletin No: CW Transceiver HW-8-4 Q11 Installation Q11, an S2091 tansistor [PN 417-116], may be either of two body styles. Be sure this transistor is installed as shown in the drawing below. ((The small flat transistor matches small flat to flat of PC board; the larger transistor the flat is "opposite" the flat of the PC board. Both types have leads 1/4" from PC board to components)). ------------------------------------------------------------------------------------------------------------------- November 15, 1976 HW-8 Bulletin No: CW Transceiver HW-8-5 Carrier Stays On, Will Not Turn Off With Key Open Cure: The wires at points K and XX on the circuit board my be interchanged. Q8 will not shut off when the key is open. ------------------------------------------------------------------------------------------------------------------ December 2, 1976 HW-8 Bulletin No: CW Transceiver HW-8-6 Poor Sensitivity on 80, 40, 15 Meter Bands; Preselector Peaks At The Wrong Position Check for proper installation of L1, L2, L3 and L4. These coils have been found to be installed in reverse order causing apparent good sensitivity on 20 meters, but poor sensitivity on 80, 40 and 15 meters. ----------------------------------------------------------------------------------------------------------------- June 5, 1978 HW-8 Bulletin No: QRP Transceiver HW-8-9 Voltage Chart Correction The cirucit board voltage chart in the HW-8 manual [PN 595-1754-07], page 80, shows IC2 pin numbers 1 and 14 interchanged. The voltages, as shown, are correct. Future manuals will be correct ------------------------------------------------------------------------------------------------------------------- November 20, 1978 HW-8 Bulletin No: QRP Transceiver HW-8-10 PN 417-240 FET's supplied with shorting wire on leads This unti may have been shipped with a shorting wire around the leads of the PN 417-240 device. The manual does not give instructions to the customer for the removal of the shorting wire. When servicing this product, check for the possibility of the shorting wire still installed on this device. The manual is being inserted with the proper instructions concerning the removal of the shorting wire. ------------------------------------------------------------------------------------------------------------------- September 19, 1979 HW-8 Bulletin No: QRP Transceiver HW-8-11 Spurs Heard as Receive is Tuned Through Strong Signals [50uv or more] all Bands This problem sounds almost like front-end instability. Check for proper installation of Q201, audio output transistor; it may be installed backwards. This may be overlooked during initial inspection because Q201 is hidden under C203, and audio stages appear to operate normally on CW. Harmonics generated by Q201 beat with VFO to generate spurs. ---------------------------------------------------------------------------------------------------------------- February 7, 1980 HW-9 Bulletin No: QRP Transceiver HW-8-12 Microphonics + + + + Information not yet available + + + + ----------------------------------------------------------------------------------------------------------------- May 16, 1980 HW-9 Bulletin No: QRP Transceiver HW-8-13 Audio Oscillation + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------ June 20, 1980 HW-9 Bulletin No: QRP Transceiver HW-8-14 Headphone Amplifier as a Service Aid + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------ July 29, 1980 HW-9 Bulletin No: QRP Transceiver HW-8-15 VFO Tuning Capacitor Rotor Plates Short to Mounting Screws + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- October 21, 1980 HW-9 Bulletin No: QRP Transceiver HW-8-16 Squeaking in Headphones on Transmit + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- January 30, 1981 HW-9 Bulletin No: QRP Transceiver HW-8-17 VFO Quits Oscillating at High End of Dial + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- February 27, 1981 HW-9 Bulletin No: QRP Transceiver HW-8-18 Defective VFO Capacitor + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- June 30, 1981 HW-9 Bulletin No: QRP Transceiver HW-8-19 Low Power Output on 15 Meters; Q9 Overheats + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- November 13, 1981 HW-9 Bulletin No: QRP Transceiver HW-8-20 Hum in Audio and Poor Sensitivity + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- November 30, 1981 HW-9 Bulletin No: QRP Transceiver HW-8-21 No HFO Output + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- November 30, 1981 HW-9 Bulletin No: QRP Transceiver HW-8-22 Relative Power Meter Reads Low on 15-Meters + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- February 9, 1982 HW-9 Bulletin No: QRP Transceiver HW-8-23 Low Power Output on Some Bands + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- Thats all that I show for the HW-8 (1966-89) NOTE: I added all the ones that are missing, showing that there are at times many holes in the information that is posted. Hopefully, those that hold the "missing years" will come forth and either post to the list, or let me have them so I can post to all. Will keep on trying. If anyone has the years 1977, and 1980-83 these are the ones I/We really need to complete what has been posted - and will be posted. This way we can keep the 'the past active'. Take care and Enjoy! 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va 22942 [Orange Co] _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] -------------------------------------------------------------------------------- Next message: Automatic digest processor: "HEATH Digest - 7 Apr 1998 to 8 Apr 1998" Previous message: Gaetan Lavergne: "HW-5400" --------------------------------------------------------------------------------