Heathkit Service Bulletins -HD-1422 (Complete)

[Joseph W Lutz]

                        March 21, 1986
HD-1422                                         Bulletin No:
Antenna Noise Bridge                            HD-1422-1

            Schematic Correction - Q101 and Q102 Base Circuit

In the base circuit of Q101, R107 [22 kilohm resistor] should connect
from the collector of Q101 to the base instead of from the +9 VDC line to
the base.  At Q102, R108 [10 kilohm resistor] should connect from the
collector of Q102 to the base.  Make these corrections on your shop
schematic for future reference.
-------------------------------------------------------------------------------------------------------------------
                        October 10, 1986
HD-1422                                         Bulletin No:
Antenna Noise Bridge                            HD-1422-1

        Inductive and Capacitive Reactance Readings Reversed

In Assembly Manuals [PN 595-3467-00 and -01], the insert drawing of C1 in
Pictorial 2-2 shows the tuning capacitor's plates 180 degrees from the
correct position [[C1 from the rear shows plates on the right side
0000-1200 location]].  This causes the Reactance knob to be installed 180
degrees from the correct position, resulting in the X[sub L] and X[sub C]
readings to be reversed.  The correct position for the capacitor plates
is shown below in drawing #2 [[C1 from the rear shows plates on the left
side 1200-2400 location]].  When the plates are in the position shown in
drawing #2, the pointer on ther Reactance knob should be at "0" on the
dial.

Pictorial 2-2 in Assembly Manual [PN 595-3467-02] is correct.  Mark the
correction in you shop manuals for future reference.
--------------------------------------------------------------------------------------------------------------------
                        February 6, 1987
HD-1422                                         Bulletin No:
Antenna Noise Bridge                            HD-1422-3

        Weak Output - Can't Get S9 Reading During Adjustments

To increase the gain of the Noise Bridge, add a .01 uF capacitor [PN
21-176] in parallel with R109 in the emitter circuit of Q102.
--------------------------------------------------------------------------------------------------------------------
                        July 31, 1987
HD-1422                                         Bulletin No:
Antenna Noise Bridge                            HD-1422-4

                          Cabinet Color Change

The commincations products are changing from a brown to a black/gray
color scheme.  Below is a listing of the part numbers for the different
color cabinet parts.

Description     Brown Cabinets          Black/Gray Cabinets
----------------        ----------------------          ----------------------------

Cabinet         PN 95-1357-1            PN 95-1357-2
Front Panel     PN 200-1505-1           PN 200-1505-2
Knob            PN 462-1178             PN 462-1236

Heath Parts Replacement is stocking both color parts.
--------------------------------------------------------------------------------------------------------------------
                        August 26, 1988
HD-1422                                         Bulletin No:
Antenna Noise Bridge                            HD-1422-5

The HD-1422A Antenna Noise Bridge has a chassis that's black and gray.
The "A" version model number is screened on the new chassis.  Change:

        From PN 200-1505-2 chassis to a PN 200-1505-3 chassis.

The -2 chassis was black and gray, but it wasn't screened with the "A"
version model number.

Below is a listing of the part numbers for the brown cabinet [HD-1422]
and the black/gray cabinet [HD-1422A].


HD-1422                 HD-1422a
Description     Brown Cabinets          Black/Gray Cabinets
----------------        ----------------------          ----------------------------

Cabinet         PN 90-1357-1            PN 90-1357-2
Front Panel     PN 200-1505-1           PN 200-1505-3
Knob            PN 462-1178             PN 462-1236

This bulletin supercedes HD-1422-4.
----------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1989 that covers the HD-1422.  Enjoy!
----------------------------------------------------------------------------------------------------------------


73 de Joe  W7LPF/4  [NNN0KUU]
QWCA - SOWP - NCVA - FISTS - RCC
Gordonsville, Va 22942 [Orange Co]

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