Heathkit Service Bulletins - HA-XX Series (Complete)

Joseph W Lutz joelutz at JUNO.COM
Tue Dec 16 22:10:38 EST 1997


                        August 1, 1974
HA-201                                          Bulletin No:
Walkie Talkie                                   HA-201-1

                        Amplifier Instability

Differences in cable characteristics between suppliers cause some
amplifiers to oscillate.

The two T/R switch transformers [T1 and T2] should be cut to 17 1/2
inches long.  This dimension will satisfy all 343-15 cables.

Future manuals will instruct the customer to cut to this new length
instead of 20".
-------------------------------------------------------------------------------------------------------------------
                        September 25, 1974
HA-201                                          Bulletin No:
Walkie Talkie                                   HA-201-2

                        Instability Of The Drake TR-22/HA-201
                                 Combination

To correct instability problems that may occur with the TR-22/HA-201
combination, install the following change:

        Change:

        Connect a 150 ohm resistor [PN 1-66] between the center pin and
        ground lug at the RF INPUT connector.

        Install this change only in HA-201 Amplifiers used with the TR-22
        Transceivers and only in cases where instability occurs on
specific
        operating frequencies.
-------------------------------------------------------------------------------------------------------------------
                        February 14, 1977
HA-201                                          Bulletin No:
Walkie Talkie                                   HA-201-3

                             PN 417-803 Identification

++++Information not yet available++++
-------------------------------------------------------------------------------------------------------------------
                        May 21, 1981
HA-201                                          Bulletin No:
Walkie Talkie                                   HA-201-4
                          Manual Correction For Q1

++++Information not yet available++++
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HA-201 Walkie Talkie
--------------------------------------------------------------------------------------------------------------------
                        February 23, 1973
HA-202                                          Bulletin No:
2 Meter Amplifier                                       HA-202-1

                          Service Seminar

I.  Output Transistors

        1.  Detecting Failure

                a]  Will not tune up to full power, one transistor may be
                      open.
                b]  Output trimmers fall beyond 1/2 turn from preset
[into 50
                      ohm load].  If non-ideal load is used, 1 turn
should be the
                      key denoting output failure.
                c]  Measure with ohm meter for shorted or open
transistor.
                      These transistors may check GOOD and still NOT
operate.

        2.  Replacement - The following sequence is important to prevent
             damage to transistors.

                a]  Remove Transistor Nuts First - Be sure to hold the
tab
                      with a pliers.
                b]  Then remove the print board mounting screws.
                c]  Unsolder leads of transistor[s] & solder in new one
[s].
                d]  Install print board screws.
                e]  Install nuts on transistors.  Be sure to hold the
flat tab with
                      pliers.  Tension may break heat sink bond resulting
in very
                      sort transistor life.

        3.  Operates in Class C mode.

                a]  Ideal for FM.  Not for AM or SSB [distortion
results].

II.     Supply Considerations

        A battery should be used. Tolerated voltages are between 12 and
16
        volts.  Expect the full load of 7 amps.  If a battery eliminator
is used,
        more than one-half volt P-P ripple will induce hum in the output.

III.    Insertion Loss

        Expect to experience loss of power when the amplifier is not
keyed up,
        [low drive power].

        1.  The unit exhibits a 1.5 to 1 VSWR when not keyed up causing
any
              wattmeter connected in the drive circuit to read
erroneously.

        2.  The higher VSWR while the unit is not keyed will cause the
output
              of the driver to be slightly detune.

              This VSWR will be lowered considerably when the units keyed
up
              because the reactance will be tuned out of the drive line
by the input
              circuit.

              The power meter should be connected between the amplifier
output
              and the dummy load.  Any readings between the driver and
amplifier
              can be misleading.  Suggested reading:  ARRL Handbook -
              Transmission Lines.

IV.      Load

        High VSWR results in mistuning of the output trimmers.

        1.  Check for indications of arcs across the mica in the output
trimmer.
              They must be replaced if any found.

V.      Drive Considerations

        Please avoid any usage outside of 5-15 watt specification.

        Failure of the transistors may occur if too high.

        The amplifier may not key up if power is too low.

VI.     Mounting

        Thermal conditions are always a consideration.  Suggest not to be
        mounted in engine compartment.  Consider mounting low in the
trunk
        allowing for the heated air to rise.  The specs call for a range
of - 30 deg
        F. to 140 deg F.

VII.    Tuning Up

        A slight additional power level can be achieved by tuning the
unit with the
        cover ON.  We will be providing a cover with holes in it for
service only.
        DO NOT recommend to the customer to drill holes in HIS unit.  The
cover
        provides for a dust free environment which may help increase the
relay
        contact life, among other things.

VIII.   Connections

        You may recommend, if desired by the customer, to change the
phono
        connectors to BNC's.

        SO-239 connectors exhibit a bump in the line.  DO NOT use or
                   recommend these.

IX.     Cables Supplied

        All the specifications were measured using the full length of
cables
        supplied.  Do not expect any less performance because the full
lengths         were used.

X.      Schematic Error

        The top condition of ferrite bead L8 goes to the collector of Q2.
 NOT to
        the junction of C11 and C12 as shown.
--------------------------------------------------------------------------------------------------------------------                            November
16, 1973
HA-202                                          Bulletin No:
2 Meter Amplifier                                       HA-202-2

                     Low Power Output [Less Than Driver Power]


Encountered unit which was drawing low current and had low output [less
than input power] upon measuring with PKW-3 [set up to measure more than
30 VR-F] it was found that the relay had a large [20V] drop across
terminals 4-3 when keyed.  A couple quick "swipes" with a burnishing tool
cured this problem.
--------------------------------------------------------------------------------------------------------------------
                        September 26, 1978
HA-202A                                         Bulletin No:
2 Meter FM Amplifier                            HA-202-3

                          Trimmer Capacitor Substitute

The first production run of the HA-202A will incorporate a substitute
trimmer [PN 31-52] at locations C1, C2, C15 and C16 due to unabailability
of the new type trimmers [PN 31-87] at this time.  The second production
will incorporate the #31-87 trimmers.  First production manuals will be
inserted [PN 591-2721] to instruct customer to use #31-52 trimmers.

It is not necessary to change the #31-87 trimmers, unless arcing is a
problem.

The #31-87 trimmers have a thicker mica insulator.
--------------------------------------------------------------------------------------------------------------------
                        July 30, 1979
HA-202                                          Bulletin No:
2 Meter FM Amplifier

                               Relay [PN 69-70] NLA

This relay is being replaced with [PN 69-91].  Since this isn't a direct
replacement, a modification kit [PN 830-37] has been made available at a
cost of $12.00.

The HA-202A Amplifier is already supplied witht he #69-91.
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HA-202 2 Meter FM
Amplifier.
--------------------------------------------------------------------------------------------------------------------
That completes the HA-XX series.

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