			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                                                     
                   HA-202-4

		               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 with the #69-91.
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1989 that covers the HA-202.  Enjoy!
--------------------------------------------------------------------------------------------------------------------
That completes the HA-XX series. 


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

