ASPiSYS ASM100 User manual

Copyright © 2009-2016 by ASPiSYS Ltd.
A S M 1 0 0
(and compatibles)
DDS FREQUENCY SYNTHESIZED
C-QUAM COMPATIBLE STEREO
AM TRANSMITTER
25W/100W carrier (100W/400W PEP)
User’s Guide
(Please read carefully before using for the first time!)

ASM100 STEREO AM TRANSMITTER USER’S GUIDE
Copyright © 2009-2016 ASPiSYS Page 2 of 10
Note: Due to constant enhancements to the device’s firmware and/or hardware, this guide is subject
to revision, without prior notice.
ASM100 is a C-QUAM compatible stereo or mono AM transmitter. It achieves extremely high stability
thanks to the latest technology DDS-based frequency generator, which provides better stability than
that typical of PLL-based systems.
To operate you must connect it to your wall outlet AC 220-240V or 110-120V (factory preset) with an
appropriate cable. There is an internal switch that is factory preset for your area. If not sure,
please ask before plugging it in.
To avoid damage, always operate the unit with the RF Out connected to an antenna, or a ‘dummy load’.
Connect your audio source to the corresponding Left and Right RCA jacks, or to the rear XLR if you
have a balanced audio feed.
O P E R A T I O N
ASM100 features a 20-character by 4-line LCD and a 4-button keyboard. When powered up, the LCD
displays a brief version and copyright message followed by the current transmission frequency.
The keyboard buttons (MENU, UP, DOWN, and ENTER) which, depending on the keyboard type, may appear
verbally or symbolically, are described next:
[]/[Menu] Acts as Menu or Escape. It cycles through all possible enabled menu screens (sequence
shown farther below) or selections within a single menu item.
[]/[Up] Acts as Up. It cycles through all possible choices in a forward or upward direction.
Menus with only two possible choices use the [  ]key instead to toggle between the
two options.
[]/[Down] Acts as Down. It cycles through all possible choices in a reverse or downward
direction. Menus with only two possible choices use the [  ] key instead to toggle
between the two options.
[]/[Enter] Acts as Enter. It enters the Settings screen from any screen. If inside the
Settings screen, it enters the editing mode for the specific item the cursor is
currently on. If editing an item, it stops the editing and accepts the changes. For
menu items that have only two possible options (e.g., toggle switches), pressing []
toggles the current option. Note: Some choices may become active immediately when
selected with the [  ]/[  ] buttons while most options (e.g., frequency) are activated
only by pressing [  ].
I N F O R M A T I O N A L I T E M S
All pages show a combination of at most four of the following predefined informational items.
FRQ: A line which shows the current OnAir/OffAir status, the frequency of operation in KHz and
the indicator [ST] when operating in Stereo Mode. The OnAir indicator is always steady.
The OffAir indicator always blinks to draw your attention.
FWD: Shows the measured forward power in Watts. The measurement is based on average (AVG) or
peak-envelope-power (PEP) reading, which is settable by the user in the Settings Screen, but
it normally should not be changed from the manufacturer’s preset value.
FWD measurements are based on the ‘PowerMeterMode’ setting of either ‘AVG’ or ‘PEP’.
REF: Shows the measured reflected power in Watts. The measurement is based on average (AVG) or
peak-envelope-power (PEP) reading, which is settable by the user in the Settings Screen, but
it normally should not be changed from the manufacturer’s preset value.
Next to the reflected power, an Alert message may be displayed, whenever the reflected power
goes above the ‘Lim REF’ setting, which may be changed from the manufacturer’s preset value
by the user. The ALERT message blinks to draw your attention. If you have turned the
‘Sounding’ setting to ‘On’ a very discrete ticking sound will be heard while the ALERT
message flashes. If you have also turned the ‘Loudness’ setting to ‘On’, the sound will be
much louder and easily noticeable from some distance.
REF measurements are based on the ‘PowerMeterMode’ setting of either ‘AVG’ or ‘PEP’.
Mod: Shows the modulation level as peak percentage (0 to 120%) and bargraph.
Date: Shows the current date as Day-of-week, date, month, and year.
Time: Shows the current time as hours, minutes, and seconds.
Temp: Shows the current LCD backlight level as percentage followed by the internal MCU temperature
in approximate degrees Celsius and Fahrenheit.

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IMPORTANT NOTE for older versions (before 2015): When there is excessive reflected power the RF
power will not be disabled unless the device is currently in a page where the REF reading is shown.
Pages where the REF reading does not show will not automatically go into ALERT / OffAir mode when
the REF reading exceeds the ‘Lim REF’ value.

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M E N U S E Q U E N C E
Menus show a different collection of informational items.
The menu sequence is shown below. Menus do not show the actual titles. The titles below are
indicative of the function and may appear slightly different on the actual LCD.
MAIN | TEMPERATURE | FORWARD | REFLECTED | MODULATION
MAIN Displays FRQ, FWD, REF, and Mod.
Older models (2014 or before):
Press []to turn the status to OnAir, or to re-attempt OnAir after auto-OffAir due
to excessive reflected power.
Press [] to turn the status to OffAir.
Newer models (2015 or later):
Press []to increase the RF output level, or to re-attempt OnAir after auto-OffAir
due to excessive reflected power. When the maximum is reached, [H] will display on
the LCD.
Press [] to decrease the RF output level. When the minimum is reached, [L] will
display on the LCD. Pressing [] once again will turn the RF output off and [0]
will display on the LCD.
Note: If the OffAir setting is saved to internal memory, then every time the device
is restarted, its RF output will be disabled, unless dictated otherwise by the saved
schedule.
TEMPERATURE Displays FRQ, Date, Time, and Temp.
Press []to increase the LCD background lighting from off (0%) to full (100%) in
10% increments.
Press [] to decrease the LCD background lighting from full (100%) to off (0%) in
10% decrements.
FORWARD Displays FRQ, Date, Time, and FWD.
Press []to turn the status to OnAir, or to re-attempt OnAir after auto-OffAir due
to excessive reflected power.
Press [] to turn the status to OffAir.
Note: If the OffAir setting is saved to internal memory, then every time the device
is restarted, its RF output will be disabled, unless dictated otherwise by the saved
schedule.
REFLECTED Displays FRQ, Date, Time, and REF.
MODULATION Displays FRQ, Date, Time, and Mod.
S E T T I N G S M E N U
FRQ
Determines the frequency of operation. The frequency is adjustable with 1KHz step from 530KHz to
1710KHz (special versions may have a different range). If a number outside the allowed range is
entered, it will be brought to the closest range limit.
Mode
Press []to toggle the mode between STEREO and MONO. C-QUAM is compatible with mono receivers so
operating at Stereo will not affect reception from typical mono receivers.
Sounding
Press []to toggle the sound option between On and Off. The sounding is used during a possible
ALERT event due to excessive reflected power.
Loudness
Press []to toggle the loudness of the sound between On and Off. Off causes a soft clicking sound
while On cause a significantly louder beeping sound.
Max FWD

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Defines the Maximum Forward power (in Watts).
Max REF
Defines the Maximum Reflected power (in Watts).
PowerMeterMode
Press []to toggle the FWD and REF metering mode between average (AVG) and peak-envelope-power
(PEP).
BFO Trim
This is a very special setting that is normally only for use at the factory during initial
calibration after manufacturing. DO NOT CHANGE THIS SETTING unless you have the necessary skills,
the necessary precision measurement instruments, and a very good reason to feel a re-calibration
will make a difference in the accuracy of the output frequency (as compared to the displayed
frequency). In either case, make sure to make a note of the current factory value so you can
restore the unit if you happen to change it. The new value is effective immediately after pressing
the []or []buttons.
Note: If you inadvertently altered this setting and don’t remember the original value, please turn
the unit’s power off and, after about 15 seconds, back on. Do NOT save any settings to internal
memory (by exiting the Setting Screen) until power is cycled.
ºC Offset
This setting defines an offset for temperature reading.
Block Menu key
Press []to toggle the option that enables/disables the Menu key for changing thru the various
display screens. This is useful if one wants to lock the display to a single screen.
Password
This field lets you define a password for accessing the Settings Screen. The password is 10
characters long and it’s made up of either spaces or upper case alphabetic characters. There are
2710–1 possible passwords.
When the password is all spaces, it is effectively disabled.
The password protection is useful for locking all settings from unauthorized changes. If used in
combination with the ‘Block Menu key’ option above, it will lock the display to a screen that the
user cannot override.
IMPORTANT NOTE: Make sure you enter the password carefully to avoid mistakes that will lock out.
The password is always visible when the screen that contains it is shown.
YY/MM/DD
Allows editing the Year (YY), Month (MM), and Date (DD) for the built-in real-time clock.
hh:mm:ss
Allows editing the Hours (hh), Minutes (mm), and Seconds (ss) for the built-in real-time clock.
MTWTF
Defines an optional schedule for workdays (Monday thru Friday).
SatSun
Defines an optional schedule for weekends (Saturday and Sunday).
Hint: Pressing []while editing a clock item will zero the item.
D E T A I L E D D E S C R I P T I O N O F V A R I O U S S E T T I N G S
Item Editing Mode
Item Editing Mode is indicated by a full-size blinking cursor. When exiting the item editing mode
back to Settings Screen item selection mode the cursor changes to a non-blinking solid underline.
Clock
The built-in real-time clock is highly accurate as it is based on a TCXO module. The only required
use for the clock is when schedules are defined (see below). You do not need to set the clock if
schedules are not used. An unset clock will start counting from August 8, 2008 00:00:00; you may
use this to know how long your transmitter has been continuously on. The clock will automatically
switch from Normal to DST based on the EU rules (i.e., last Sunday in March from Normal to DST and

ASM100 STEREO AM TRANSMITTER USER’S GUIDE
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last Sunday in October from DST to Normal, at 3:00am). This may be different from rules in other
parts of the world.
When in clock editing mode the blinking cursor appears on the LCD at the position to edit next. Use
[]/[]to change the current element (e.g., hour), or []to clear the current element value to
zero. When done editing, press []to accept the changes, and exit the editing mode returning back
to the clock display mode. The clock will continue running with the new settings.

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WARNING: If an internal backup battery (type CR2032 or CR2025) isn’t installed, the clock is lost
when the unit is turned off, or the power supply is momentarily lost. This is no problem for normal
operation unless schedules are defined. In that case, it is presumed that you make sure a backup
battery properly backs the clock’s power.
MTWTF schedule Allows editing of the daily schedule for automatic RF Output On/Off switching. The
daily schedule is effective only for weekdays except Saturday and Sunday (which are controlled
separately by the SatSun schedule). To edit the current schedule, you must enter the schedule-
editing mode by pressing []. When in schedule editing mode the blinking cursor appears on the LCD
at the position to edit next. Use []/[]to change the current element (e.g., hour), or []to
clear the current element value to zero. The left-hand-side time is for the On Time while the
right-hand-side time is for the Off Time. When done editing, press []to accept the changes, and
exit the editing mode. When exiting the edit mode, the start and end times will be put in the
correct order so that the start time is always before the end time.
If you need to disable the current schedule (so that the unit operates full time in the inherited RF
Output state during the corresponding days for the current schedule), you need to set both the On
Time and the Off Time to zeros. The new settings will be effective immediately.
SatSun schedule Defined in the same was as the MTWTF schedule (see above), except that it applies to
Saturdays and Sundays only.
Exiting the Setting Screen automatically saves any changes to an internal non-volatile memory.
These will be the settings used when ASM100 is powered next time.
Important note: Current clock is lost when the device is powered off (or if there is any loss of
power supply), but any saved Daily or Weekend schedules aren’t. This means when the unit is powered
up again (with an incorrect clock setting), the schedules will appear to be random! Do not use
schedules if some form of UPS doesn’t protect your device.
All keyboard buttons auto-repeat if held pressed. This is useful mostly for the []or []buttons
so you can quickly locate a different value. While selecting from any list in a menu, if you keep
the button continuously pressed, the speed will increase from normal to faster. If while searching
in faster speed you happen to go beyond the selection you want, you can use the opposite direction
([]/[]) button from the one you were using to go back, either continuously or one at a time.
A U D I O L E V E L A D J U S T
Although the unit is factory trimmed, the trimmers next to the Audio RCA jacks can be used to adjust
only the unbalanced audio level to your liking, for each channel (left and right) separately. Turn
clockwise to increase the audio level. (In older versions, these same trimmers also affect the
signal coming from the XLR inputs. In newer versions, this is no longer the case as the levels are
fixed and they are not user adjustable.)
It is possible that your audio source produces a higher or lower level signal than what’s expected.
A good method to correctly adjust the audio level is described below:
Turn the RF output level to the minimum (i.e., fully clockwise for older models –‘L’ indication for
newer models equipped with a digital RF output level menu adjustment).
Start by connecting an audio source at its lowest possible level to the appropriate inputs. Both
inputs should be given the same signal (monophonic) at the same time. It’s better if you can supply
a steady 400 Hz tone from your audio source. (Avoid to apply 1 KHz tone for this measurement.)
Next, start increasing the level of your audio source until the Modulation reading (Mod) shows 100%.
Stop the 400 Hz audio generator from the source and connect your actual program audio with a level
that will not exceed the level used with the 400 Hz tone when you’re reading Modulation of 100%.
Nevertheless, it’s possible for the program audio to reach 125% momentarily during peaks but it’s
best to keep it as close as possible to 100% as your compressor allows.
As with all AM broadcasts, it’s recommended that you use heavy compression on the audio program
before it enters the transmitter. The transmitter has a built-in pre-emphasis for AM, and if using
some audio processor with its own pre-emphasis setting, you must have it disabled.
R F O U T P U T L E V E L A D J U S T
It is recommended that the following procedure be followed after the audio level has been set (see
above).
IMPORTANT (for older units equipped with a rear-panel trimpot for RF output
level): Turning the trimmer fully clockwise, you get the maximum RF power
output, while counter-clockwise you get the minimum RF power output. It works
like a gain control.
The trimmer pot is located in the rear panel, right below the XLR inputs.
Newer units have a digital RF output level adjust from the frequency menu screen.
Normally, the RF output level only has to be set once. If you’re going to the frequency of
operation, first reduce it to the minimum, change the frequency, and then re-adjust to the desired

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power level as shown on the LCD. Under any circumstances, we do not recommend going above 25W while
adjusting with a non-modulated signal.
ASM100 has been set at the minimum RF output level before shipping. This is done to protect it in
case someone turns it on without first having connected an appropriate load or antenna.
Units with a digital RF output level adjustment (newer) will automatically switch to the minimum RF
output level every time a new frequency is selected.
First, before changing the factory settings, attempt to tune the antenna with unmodulated carrier,
so that it has the least VSWR possible. Provided the antenna is correctly tuned for the
transmission frequency and it appears as a 50 Ohm load at the transmitter’s output, we may start
increasing the output level of the transmitter up to the desired level. This setting must be done
from within the Main screen (which shows both FWD and REF) and without having any modulation on the
transmitter, so that we can measure power of just the carrier signal. The ‘PowerMeterMode’ setting
must be in AVG mode, which is the typical/preferred setting.
You should increase the output power up to point we read 25W (or 100W, depending on model).
Absolute maximum allowable setting for correct operation is about 28W (or 130W), but above 25W (or
100W) it may cause a small distortion to the audio when modulation exceeds 100%.
ATTENTION: Even if the RF power trimmer allows increasing the power much higher, one should NEVER
operate the transmitter at an output level (either modulated or unmodulated) above the respective
model’s maximum carrier for more than five (5) minutes. Doing so may seriously damage the final
amplifier stages.
When making adjustments, please note the FWD reading on the device and wait for about 10 seconds for
the reading to stabilize before making additional adjustments. Also, when you reach the desired
level, please adjust slowly in small steps while verifying the output power (FWD) on the display
which follows after a small delay.
Next, connect audio at low level and listen for any distortion. A distortion may be caused if the
stereo audio signal applied to the inputs is of too high a level. If this should happen, you may
need to re-adjust your audio source’s modulation to a lower level.

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VERY IMPORTANT NOTE, READ CAREFULLY
This device is a high power AM transmitter. Use of this
device may be in violation of local laws/regulations,
depending on your region. If unsure, please check with
your local telecommunications authorities. Under no
circumstances should it be used in violation of any such
laws/regulations. The responsibility for legal/proper
usage rests solely on you!
For proper operation, it must be connected to a 50 Ohm
load or to a tuned antenna capable of accepting power of
even 800W.
Thank you for purchasing the ASM100 by ASPiSYS Ltd.

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Technical Specifications
Subject to change without notice
RF Output Frequency
520 to 1710 KHz (Special versions may vary according to requirements)
Minimum Step
1 KHz
Frequency Accuracy
+/- 0.5 Hz max. (DDS)
RF Output Level (ASM100-25)
25 W carrier (adjustable from 5 W) @50 Ω
RF Output Level (ASM100-100)
100 W carrier (adjustable from 5 W) @50 Ω
Output Impedance
50 Ω
Harmonics (out-of-band)
-60 dBc
Audio Level Control
Adjustable for unbalanced input
RF modulation
AM (Mono, or C-QUAM Stereo System)
Input Level
0.25 V up to 2.5 V p.p. (adjustable unbalanced)
Input Impedance
10 KΩunbalanced, 600 Ωbalanced
Pre-emphasis
0 and 75 μS or 50 μS (preset according to your country system)
Total Harmonic Distortion
<0.4% @ 1 KHz
Operating Voltage
115 or 230 VAC (according to country)
Current Consumption (ASM100-25)
1.5A 1Α max.
Current Consumption (ASM100-100)
6.0 A 3Α max.
For technical support email [email protected], or write to:
ASPiSYS Ltd., P.O.Box 14386, Athens 115 10, Greece (EU), or call: ([phone] FAX: [phone].
We are in the GMT+2 time zone.