Heathkit Service Bulletins - HA-XX Series (Complete)
Randy Kaeding
randyk at PARRETT.NET
Wed Dec 17 21:44:04 EST 1997
Please make note that the HA-201 is not a walkie talkie. It is a 2-meter
amplifier for use with a 2-meter hand held.
Tnx,
Randy, K8TMK
"One of the Hams at Heath"
----------
> From: Joseph W Lutz <joelutz at JUNO.COM>
> To: HEATH at LISTSERV.TEMPE.GOV
> Subject: Heathkit Service Bulletins - HA-XX Series (Complete)
> Date: Tuesday, December 16, 1997 10:10 PM
>
> 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++++
>
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----------------------------------------
> Thats everything I hold up to 1985 that covers the HA-201 Walkie Talkie
>
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> 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.
>
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----------------------------------------
> 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.
>
----------------------------------------------------------------------------
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> Thats everything I hold up to 1985 that covers the HA-202 2 Meter FM
> Amplifier.
>
----------------------------------------------------------------------------
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> That completes the HA-XX series.
>
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