AMERITRON ATP-102 User manual

AMERITRON ATP-102
AMPLIFIER TUNING
PULSER Il
INSTRUCTION MANUAL
Carrier
,* tune
duty ..
ATP-102
Tuning
Pulser
PLEASE READ THIS MANUAL BEFORE OPERATING THIS EQUIPMENT !
AMERITRON
116 Willow Road
Starkville, MS 39759 USA
662-323-8211
Copyright © 1997 Ameritron

ATP-102 Instruction Manual Tuning Pulser I]
Ameritron ATP-102 Tuning Pulser II
The Ameritron ATP-102 Tuning Pulser II relieves temperature related stress on
amplifiers, tuners, and dummy loads while allowing proper system adjustments.
It allows amplifiers to be properly adjusted without the use of long steady
carriers.
The Ameritron ATP-102 Tuning Pulser II allows tuning of an amplifier with full
required drive from the transceiver without over-heating the finals or anything
else in the RF line. It sends a series of pulses to the transceiver allowing the
peak power to be high enough to drive the amplifier to full power, but with the
average power being low enough not to over-heat the final(s).
The Ameritron ATP-102 Tuning Pulser I] works with any solid state amateur
transceiver or transmitter, and all other equipment using positive keying line
voltages below 50 volts open circuit and 100 mA closed key current. It can also
be used with negative voltage key lines (commonly found in older tube type
radios)
provided
keying
voltages
are
below
25
volts
dc
open
circuit.
The Ameritron ATP-102 Tuning Pulser II is a valuable troubleshooting and
diagnostic aid. The Ameritron ATP-102 Tuning Pulser II can be used in
performance tests of QSK systems, wattmeters, and other equipment.
The Ameritron ATP-102 Tuning Pulser II uses a single 9-volt battery for power,
with battery life dependent on operating and storage time. To install the battery
remove the cover by removing the two screws (one on each side) that secure it.
A battery clip and holder, located on the left side of the enclosure, are provided
for installing the 9-volt battery.
Technical Description
The Ameritron ATP-102 Tuning Pulser II uses a 555 timer driving an FET open
drain switch. Two front panel controls allow independent adjustment of both
pulse repetition rate (PULSE RATE) and on-to-off time duty cycle (DUTY
CYCLE).
PULSE RATE is adjustable from about 17 to 40 pulses per second, while DUTY
CYCLE is adjustable from about 10 to 90 percent. The keying time intervals are
typically adjustable from 2- 40 mS "on" time, and a 24 to 60 mS pulse repetition
time interval.
Minimum duty cycle and the slowest PULSE RATE occur at the full
counterclockwise settings of both front panel controls.

ATP-102
Instruction
Manual
Tuning
Pulser
I]
The
CARRIER
button
is
a
momentary
contact
switch
that
temporarily
locks
the
transmitter in a continuous carrier transmit mode.
The
PULSE
button
is
a
latching
switch
that
activates
the
pulse
circuit
when
pressed in and locked.
Speech Duty Cycle
The
duty
cycle
of
average
power
to
peak
envelope
power
varies
widely
in
the
real
world.
Every
voice
and
system
varies,
no
universal
duty
cycle
of
peak
to
average
power
applies
to
the
many
real-world
combinations
of
voices
and
equipment.
Unprocessed
speech
usually
has
an
average
power
between
one
percent
and
ten
Pp
Pp
y
g
percent
of
peak
envelope
power.
Sustained
speech,
such
as
a
long
"hello",
produces
average
power
levels
that
typically
range
from
10
to
30%
of
PEP.
Heavy
speech
processing
increases
the
average
power,
pushing
the
short
term
average power of normal speech to 30% or more.
During
normal
voice
operation,
most
equipment
heat
is
generated
by
the
quiescent
current
required
to
make
the
transmitting
system
linear.
Proper
amplifier
or
transmitter
tuning
require
adjustments
at
maximum
peak
power,
generally
with
maximum
available
drive
from
the
exciter.
A
continuous
tone
or
carrier
is
generally
used
during
adjustment,
and
the
amplifier
is
generally
tuned
for maximum
output.
The
continuous
single
tone
carrier,
commonly
used
to
adjust
the
PA
or
tuner,
will
raise
heat
significantly.
The
Ameritron
ATP-102
Tuning
Pulser
II
allows
proper
tuning
while
driving
the
PA
with
a
low
duty
cycle
waveform.
It
is
NOT
necessary
to
use
a
peak
reading
meter
when
adjusting
an
amplifier
or
tuner
with
the
Ameritron
ATP-102
Tuning
Pulser
II,
although
the
lack
of
a
true
peak
reading
meter
will
prevent
you
from
knowing
the
amount
of
peak
power
produced.
N

ATP-102 Instruction Manual Tuning Pulser II
PULSE RATE and DUTY CYCLE
The Ameritron ATP-102 has two front panel controls labeled Pulse rate and
duty cycle. As indicated by the names, these controls adjust the rate at which the
transmit keying pulses occur (pulse rate), and the ratio of on- to-off time (duty
cycle).
Some care must be used to insure PULSE RATE is slow enough, and the DUTY
CYCLE is long enough, to be within the keying response limits of the exciter
and meter. If the pulse rate is too fast and/or the duty cycle is too long, the
pulses will blur into one long steady signal.
The typical exciter has a leading edge rise time and tailing edge decay time of a
few milliseconds. This stretches the pulse duty cycle out, making the actual RF
envelope have a longer duty cycle than the actual keying waveform from the
Ameritron ATP-102 . Because of this effect, the Ameritron ATP-102 Tuning
Pulser I] may actually produce a 100% duty cycle waveform at high (clockwise)
PULSE RATES with longer (clockwise) on-time DUTY CYCLE settings.
If the pulse rate is too slow and/or the duty cycle too slow, peak power will not
be reached. All exciters have a delayed response to the leading edge of the
keying waveform. This delay may prevent full peak power from being reached if
the duty cycle is too short. Most peak meters have limited response time, this
causes lower power readings with short duty cycle pulses.
Another problem is nearly all meters have limited storage time, causing the
meter to "fall-back" during the time interval between RF pulses. To obtain the
most accurate meter readings, both PULSE RATE and DUTY CYCLE should
be set far enough clockwise to allow maximum peak power to be indicated on a
scope or peak reading meter.
Some peak meters do not read true peak power at all, instead reading something
less than the true peak power. If your meter reads less power when the pulser is
used, compared to the power when a steady or near steady carrier is produced,
your meter is probably not a good peak reading meter. Nearly every radio and
amplifier produces more peak power than steady carrier power, because of ALC
response time and power supply voltage sag under load. Too much duty cycle
on-time can cause unwanted component heating.
2

ATP-102 Instruction Manual Tuning Pulser I]
The
ideal
compromise
(especially
for
tuning
amplifiers)
is
achieved
when
the
PULSE
RATE
and
DUTY
CYCLE
controls
are
near
the
counter-clockwise
end
where the power drops off, but adjusted slightly clockwise from the point where
the peak power meter starts to fall back. If such a setting can not be found, it is a
strong indication the meter does not indicate peak power accurately.
Connecting the Ameritron ATP-102 Tuning Pulser Il
The Ameritron ATP-102 Tuning Pulser II connects to the CW Key jack of your
exciter via the Ameritron ATP-102 Tuning Pulser II rear panel jack labeled
"Output". The Output jack is a standard RCA phono plug, with the center pin
connected to the positive voltage keying line (less than 50 volts and 100 mA)
and the outer shell grounded. If the case of the Ameritron ATP-102 Tuning
Pulser II is kept isolated from ground, the Ameritron ATP-102 Tuning Pulser I]
can be used with negative keying line voltage radios provided radio keying line
voltages are below 25 volts. The primary concern is the shock hazard and
potential of accidentally keying the rig if the cabinet of the Ameritron ATP-102
Tuning
Pulser
II
or
the
operator
comes
in
contact
with
grounded
equipment.
WARNING: Never use the ATP-102 with negative keying line rigs
that have over 25 volts on the key jack.
Tuning Amplifiers
Nearly all power amplifiers (PA's) are properly tuned when maximum envelope
power is obtained with full exciter output. Tuning the amplifier to match exciter
peak power prevents gain compression (flat-topping), reduces splatter and
distortion,
and
reduces
the
chance
of
PA
damage
from
arcing.
Maximum average power is directly related to (although considerably less than)
maximum peak power. While the lack of a good peak reading meter prevents
measurement
of
true
peak
power,
virtually
any
RF
power
meter
will
provide
a
correct indication of tuning. When the amplifier is tuned to produce maximum
average power when driven with a constant rate and duty cycle pulse, it is almost
certainly
tuned
for
maximum
peak
power.
The least damaging and cleanest PA tuning condition generally occurs when the
PA is peaked slightly beyond maximum output, in a direction that OPENS or
UNMESHES the loading capacitor (this capacitor is sometimes called LOAD,
ANTENNA,
COUPLING,
or
MATCHING).

ATP-102 Instruction Manual Tuning Pulser I]
Caution: Be very careful to avoid applying full drive power to the PA
without having the load control open far enough. When power
amplifiers are undercoupled, tank voltages can be extremely
high. This may cause tank components, such as the bandswitch
or tuning capacitor, to arc and fail. It also stresses the tube and
other components with needlessly high voltages. The Ameritron
ATP-102 Tuning Pulser II will NOT prevent voltage damage to
components.
Adjust the two front panel controls to a 10 o'clock position. With the amplifier
in stand-by, push the Carrier Tune button and adjust the transceiver's power
control to the rated drive power of the amplifier. Place the amplifier into operate
mode and depress the pulse tune button on the Ameritron ATP-102 Tuning
Pulser II. Tune the amplifier for peak output power.
Note: Due to the response time of most non-peak-reading RF watt meters, the
meter will read a low average power, but the amplifier will be tuned for
full peak power.
While momentarily pressing the carrier tune button, the RF watt meter should
read full power of the amplifier. The amplifier is now tuned for full power.
For best linearity, it is best to reduce the transceiver's power slightly after tuning
the amplifier.
Testing QSK Systems
The Ameritron ATP-102 Tuning Pulser II can be used to evaluate QSK systems.
In one test configuration, a continuous signal source is loosely coupled to the
dummy load. The receiver is tuned to this signal source, and the Ameritron ATP-
102 Tuning Pulser II controls are adjusted until the test signal is clearly audible.
The maximum QSK receive speed is found by measuring the PULSE RATE, and
multiplying the PULSE RATE by 2.4. The DUTY CYCLE should be set for
normal sounding CW dots during this test, or a 1:1 ratio.
The transmission waveshape can be checked by looking at the RF output on a
scope, with the scope triggered or synchronized to the keying line signal. A
normal CW signal has a smooth rise and fall time of about one millisecond, with
no overshoot or undershoot. Switching from manual operation to full QSK
should not disturb the keying waveform, or change the on and off time period.
Nn

ATP-102
Instruction
Manual
Tuning
Pulser
Il
Testing Wattmeters
Wattmeters
can
be
tested
by
measuring
the
single
tone
power
with
a
barefoot
exciter
running
off
of
a
regulated
supply,
and
adjusting
an
oscilloscope
to
read
near
full
screen
with
that
carrier.
By
activating
the
ATP-102
with
the
PULSE
RATE set approximately
mid-range, and adjusting the DUTY CYCLE control
until the full peak envelope voltage is just displayed on the scope, the meter can
be evaluated. A good peak reading meter should indicate the same amount of
peak power with the ATP-102 pulsing the carrier as it indicates with a
continuous
carrier,
as
long
as
the
maximum
scope
deflection
remains
the
same.
RFI and TVI Troubleshooting
The
Ameritron
ATP-102
Tuning
Pulser
II
can
be
used
to
activate
the
transmitter
with
a
pulsed
signal
of
full
peak
power,
without
undue
equipment
heating.
This
will allow you to move to the location of the device being interfered with, while
safely
operating
the
transmitter
at
high
power.
You
can
add
filters,
grounds,
and
move
cables
on
the
device
being
interfered
with
without
fear
of
overheating
your
transmitter.
The
short
duty
cycle
also
reduces
interference
to
other
amateur
operators.
Be
sure
to
have
a
licensed
operator
attending
your
station,
and
to
conform
to
all
FCC rules regarding CW emissions.
Technical Assistance
For technical assistance please call Ameritron at 662-323-8211. You will be
best
helped
if
you
have
your
unit,
manual
and
all
information
on
your
station
handy
so
you
can
answer
any
questions
the
technicians
may
ask.

Tuning Pulser II
ATP-102 Instruction Manual
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ATP-102 Instruction Manual Tuning Pulser I]
Parts List
Resistor, IK OHM 100-3100
Resistor, 1OK OHM 100-4100
TRI‘ Resistor, 47K OHM 100-4470
l
R6,
R7
Resistor,
POT,
500K
OHM
55-5500-1
PQl
CT
FET.2N7000_
305-7000
IC, Timer, NESSSCN
311-1003
Switch, Locking, 2P2P
504-2022