User's Manual

T4
LECTROSONICS, INC.
12
Frequency Blocks and Ranges
The table below lists the factory designated frequency
ranges available for the T4 IFB Transmitter.
Each T4 transmitter is built to cover a pre-selected
range of frequencies (a “block”) as shown below. The
transmitter will tune to any of 256 different frequencies
within this factory assigned block.
The block number is determined by this formula:
25.6 × Freq. (MHz) = Lowest freq. (MHz) in
the block
To determine a block number from a frequency:
Freq. (MHz) divided by 25.6 = Block number
It is handy to remember these formulas, in case you do
not have a copy of the table. For example, suppose you
need to know which block covers 685.500 MHz, which is
in the middle of the Block 26 frequency range.
685.500 divided by 25.6 = 26.77734375
FREQUENCY ANT SLEEVE ANTENNA
BLOCK RANGE (MHz) COLOR WHIP LENGTH
21 537.600 - 563.100 Brown 4.74”
22 563.200 - 588.700 Red 4.48”
23 588.800 - 614.300 Orange 4.24”
24 614.400 - 639.900 Yellow 4.01”
25 640.000 - 665.500 Green 3.81”
26 665.600 - 691.100 Blue 3.62”
27 691.200 - 716.700 Violet (Pink) 3.46”
28 716.800 - 742.300 Grey 3.31”
29 742.400 - 767.900 White 3.18”
944 944.100 - 951.900 Black 3.10”
The fi rst two digits left of the decimal are the block
number. In this case, 685.500 MHz falls within block 26.
Block 944 is an exception to this block numbering sys-
tem and depicts the actual frequency of the block since
it is only a 6MHz band with 78 frequency channels.
The T4 IFB transmitter antennas are color coded to
indicate the frequency block that they operate within.
The length of the antenna varies with the frequency
block. The actual length of the antenna is not as criti-
cal as it might appear in the table below. The usable
bandwidth of the detachable antenna is +/- 50 MHz
from the block’s center frequency, so it is acceptable to
use an antenna from an adjacent block above or below
the operating frequency if some loss in range can be
tolerated.
Part of block 23 is not used since it covers a 608 to 614
MHz band that is illegal for use with wireless micro-
phones.