Synthesized VHF IFB Transmitter
Rio Rancho, NM
9
Frequency Selection
The R1A-VHF receiver provides two 16-position rotary
switches to select the frequency, adjusted with a small
screwdriver inserted in the slot in the middle of the
switches. The left-hand switch makes 2.8 MHz steps
and the right-hand switch in 175 kHz steps, with the
switch positions marked in hexadecimal numerals 0
through F.
Frequencies are designated by two characters, such
as B5, where first character is the left-and switch posi-
tion and the second character the right-hand switch
position. Thus, in this example, B5 would indicate
205.775 MHz, as shown in the table below.
175K SWITCH (RIGHT)
0
1
2
3
2.8M
4
SWITCH
5
(LEFT)
6
7
8
196 500
196 675
196 850
197 025
197 200
197 375
197 550
197 725
8
196.
196.675
196.850
197.025
.200
197.375
197.550
197.725
9
A
B
C
D
E
F
175K SWITCH (RIGHT)
0
1
2
3
2.8M
4
SWITCH
5
(LEFT)
6
7
8
197 900
198 075
198 250
198 425
198 600
198 775
198 950
199 125
8
197.900
198.075
198.250
198.425
198.600
198.775
198.950
199.125
9
A
B
C
D
E
F
The front panel LCD on the IFBT4-VHF transmitter
displays frequency in MHz and in the two character
hexadecimal method.
0 1
2
3
4
5
6
7
8
9
A
B
C
D
E F
0 1
2
3
4
5
6
7
8
9
A
B
C
D
E F
Frequency select switches on the
IFBR1A-VHF receiver
2.8 MHz
steps
175 kHz
steps
Frequency in hex
Frequency in MHz
IFBT4-VHF transmitter LCD
