HMa-941
LECTROSONICS, INC.
10
PH (phantom power supply)
The transmitter input jack can provide phantom power
for the attached microphone if needed, with voltages
at 5, 15 or 48 or be turned off. Use the UP and DOWN
arrow buttons to select the desired setting. Phantom
power will consume a slight amount of battery power.
About the Phantom Power Supply
Three phantom voltages are selectable from the control
panel. The voltages are:
•
5 Volts
for lavaliere microphones,
•
15 Volts
for some professional mics requiring high
current and for many common stage mics that will
operate over a wide phantom Voltage range of 12 to
48 Volts. With the proper adapter, this position can
also be used with T power microphones. See our
web site for details on finding or making the proper
adapter.
•
48 Volts
for microphones that do in fact require a
supply greater than 18 Volts. (See below for a dis-
cussion of why 42 and not a “true” 48 Volts.)
For longest battery life use the minimum phantom volt-
age necessary for the microphone. Many stage micro-
phones regulate the 48 Volts down to 10 Volts internally
anyway, so you might as well use the 15 Volt setting and
save some battery power. If you are not using a micro-
phone for the input device, or are using a microphone
that does not require phantom power, turn the phantom
power off.
Phantom power should only be used with a fully float-
ing, balanced device such as most microphones with
a 3-pin XLR connector. If you use the phantom power
with an unbalanced device or if pins 2 or 3 are DC con-
nected to ground, then you will draw maximum current
from the power supply. The HM is fully protected against
such shorts but the batteries will be drained at twice the
normal rate.
The transmitter can supply 4 mA at 42 Volts, 8 mA at 15
Volts, and 8 mA at 5 Volts. The 42 Volts setting actually
supplies the same voltage to a 48 Volt microphone as
the DIN standard arrangement due to a dynamic bias-
ing scheme that does not have as much voltage drop
as the DIN standard. The 48 Volt DIN standard arrange-
ment protects against shorts and high fault current with
high resistance in the power supply feeds to pins 2 and
3. This provides protection if the supply current is ac-
cidentally shorted to ground and also keeps the micro-
phone from being attenuated by the power supply.
The HMa improves on those functions and is able to
use less power from the battery by using constant
current sources and current limiters. With this dynamic
arrangement the HMa can also supply more than twice
the current of competing 48 Volt plug on units and pro-
vide four times the current for some very high end 15
Volt microphones.
FREQ Button
The operating frequency can be adjusted according to
the frequency in MHz or a two-digit hexadecimal code.
Press the button repeatedly to switch between the two
displays. The display switches when the button is first
pushed; push and hold the button in the desired mode
and use the UP and DOWN arrow buttons to make the
adjustment.
Hex code numbering came about years ago when the
first synthesized wireless equipment was introduced.
Two 16-position rotary switches were used to set the
frequency. 16 on one switch and 16 on the other switch
yielded 256 frequencies (16x16=256). While there are
no 941 band models that use these switches, hex code
numbering is easier way to remember than frequencies
expressed in MHz with six numerals.
In this example, the same frequency is displayed in
MHz and the equivalent hex code.
The hex code is a hexadecimal numbering sequence
that progresses upward from lowest to highest fre-
quency using the numerals and letters from 0 through
F. When the frequency is on a 100 kHz step, the hex
code will display two
00’s for the last two digits, which
is easy to remember (3A in the example above). When
the step size is set to 25 kHz, the last two digits will be
00, 25, 50 or 75 (3A.25 in the example below), which
is still easier to remember than all six numerals of the
frequency in MHz.
Locking/Unlocking the Control Panel
Simultaneously pressing and
holding both the UP and
DOWN arrow buttons during
normal operation starts the
Lock timer. The timer starts at
three and counts down to zero.
When the timer reaches zero, the buttons on the control
panel are locked.
With the controls locked, the AUDIO and FREQ buttons
can still be used to display current settings. Any attempt
to change a setting by pressing either the UP or DOWN
arrow button will result in an on-screen reminder (
Loc
)
that the controls are locked. Remove the batteries to
unlock the control panel.
Important: Once the transmitter is locked, it
cannot be unlocked or powered off using the
buttons. The only ways to unlock a locked
transmitter are to remove the battery or unlock it
via the remote control.
Summary of Contents for HMA-941 Series
Page 15: ...Plug on UHF Transmitter Rio Rancho NM 15 ...
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