Heathkit Service Bulletins - HW-XX Series (Complete)
Joseph W Lutz
joelutz at JUNO.COM
Fri Nov 7 18:57:23 EST 1997
June 15, 1967
HW-12
Bulletin No.
80M SSB Transceiver
HW-12-1D
VFO Drift
An incorrect shipment of coils has been included in a recent production
run of the HW-12, HW-22 & HW-32.
The coil Part Number is 52-25 & has a N-750 ceramic installed inside the
can...rather than a silver mica.
The mis-manufactured coil causes drifting in the circuit...which can be
corrected by replacing with a NO, 52-25 of proper construction. All
stock currently on hand in the parts dept is correctly manufactured.
------------------------------------------------------------------------------------------------------------------
April 15, 1968
HW-12
Bulletin No:
80M SSB Transceiver
HW-12-2D
IF Feedback in Receive
Mode
R-121 may be changed from 12K ohm to 22K ohm 2W (Part NO. 1-11-2) to stop
IF feedback in receive operation.
-----------------------------------------------------------------------------------------------------------------
April 18, 1968
HW-12
Bulletin No:
80M SSB Transceiver
HW-12-3D
IF
Oscillating
DELETE: (2) I-16 (5) RESISTOR, 4.7K OHM
ADD : (2) I-16 (6) RESISTOR, 4.7K OHM
DELETE: (2) I-22 (5) RESISTOR, 22K OHM
ADD : (2) I-22 (4) RESISTOR, 22K OHM
DELETE: (4) 83-69-4 (1) CIRCUIT BOARD, 85-69 SCREENED
ADD : (4) 85-69-9 (1) CIRCUIT BOARD, 85-69 SCREENED
NOTE: (R91) will reduce action of the S-Meter.
------------------------------------------------------------------------------------------------------------------
September 26,
1968
HW-16
Bulletin No:
Novice Transmitter
HW-16-1
Side
Tone
When using the HW-16 with a VFO sometime a partial operation of the
sidetone oscillator takes place due to an increased loading on the bias
voltage. This can be corrected by changing R-69 from a 120K hom resistor
to a 220K ohm resistor (PN 1-29). Also, the original schematic shows
R-16 as a 4700 ohm resistor which is incorrect. R-16 should be shown as
a 5600 ohm resistor.
--------------------------------------------------------------------------------------------------------------------
September 9, 1971
HW-16 Bulletin No:
Novice Transmitter HW-16-2
Resistor Failure
Due to repeat failure of a resistor in the field, the following change
should be made
in all units being serviced:
CHANGE: R21 22K 1 WATT TO 2 WATT [PN 1-11-2].
----------------------------------------------------------------------------------------------------------------
June 15, 1967
HW-22 Bulletin No:
40M SSB Transceiver HW-22-1D
VFO Drift
An incorrect shipment of coils has been included in a recent production
run of the HW-12, HW-22 & HW-32.
The coil Part Number is 52-25 & has a N-750 ceramic installed inside the
can...rather than a silver mica.
The mis-manufactured coil causes drifting in the circuit...which can be
corrected by replacing with a NO, 52-25 of proper construction. All
stock currently on hand in the parts dept is correctly manufactured.
------------------------------------------------------------------------------------------------------------------
April 15, 1968
HW-22 Bulletin No:
40M SSB Transceiver HW-22-2D
IF Feedback In Receive Mode
R-121 may be changed from 12K ohm to 22K ohm 2W (Part NO. 1-11-2) to stop
IF feedback in receive operation.
------------------------------------------------------------------------------------------------------------------
June 15, 1967
HW-32 Bulletin No:
20M SSB Transceiver HW-32-1D
VFO Drift
An incorrect shipment of coils has been included in a recent production
run of the HW-12, HW-22 & HW-32.
The coil Part Number is 52-25 & has a N-750 ceramic installed inside the
can...rather than a silver mica.
The mis-manufactured coil causes drifting in the circuit...which can be
corrected by replacing with a NO, 52-25 of proper construction. All
stock currently on hand in the parts dept is correctly manufactured.
------------------------------------------------------------------------------------------------------------------
April 15, 1968
HW-32 Bulletin No:
20M SSB Transceiver HW-32-2D
IF Feedback In Receive Mode
R-121 may be changed from 12K ohm to 22K ohm 2W (Part NO. 1-11-2) to stop
IF feedback in receive operation.
-------------------------------------------------------------------------------------------------------------------
May 8, 1979
HW-32A Bulletin No:
20M SSB Transceiver HW-32-1
Relay Chatter In The VOX Mode
While the relay is chattering, monitor the junction of R-200 and C-204
with an oscilloscope. If you see a negative 12-Volt pulse, 4
milliseconds wide, remove C-203.
C-203 is intended to "speed-up" the cut-off voltage to V1B when going to
the receive mode. However, it is also the cause of the relay chatter.
When in the transmit mode, V10 is cut off and V2B is saturated, so that
the relay is energized. If no one is speaking into the microphone, V10
will saturate and V2B will cut off. This disconnects pin 1 of the relay
from R-203 and sends a negaitve pulse through C-203/R-200, the MIC GAIN
Control, C-14 and on to the grid of V10. V10 cuts off, causing V2B to
again turn on and re-energize the relay. After a short period, V10 will
again saturate, repeating the loop.
Remove C-203 on an "AS-NEEDED" basis only.
--------------------------------------------------------------------------------------------------------------------
Enjoy!
73 de Joe W7LPF/4 [NNN0KUU]
QWCA - SOWP - NCVA - FISTS - RCC
Gordonsville, Va 22942 [Orange Co]
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