Ramsey Electronics COM 3 User Manual

STANDARD EIA CTS TONES (Hz)
Table 3.1
3.9 1 KHz INTERNAL TONE
Touching the 1 KHz key will enable the
internal 1 KHz tone. In AM mode, the
MODULATION knob will control the percent
modulation, in FM mode it will control the
deviation.
3.10 EXTERNAL SOURCE INPUT
Touching the EXTERNAL key will allow the
connection of an external tone source. (see
specifications Chapter 1 for limitations on this ' -
input) The source is looped through the Com 3
using the IN and OUT jacks located under the
EXTERNAL key. The percentage of modulation
in AM mode is adjusted using the
MODULATION knob, in FM mode it will control
the deviation.
«9.31 COMBINING CTS AND INTERNAL /
EXTERNAL TONE SOURCES
.. Select the CTS frequency desired and
adjust for the desired deviation (for example 0.6
KHz). Then select the 1 KHz mode. The 1 KHz
tone will now have a deviation of 3 KHz, and will
vary in a 5/1 ratio with the CTS tone. (0.6 KHz
CTS deviation will produce 3 KHz deviation of
the 1 KHz tone).This ratio was chosen since the
most common deviation for CTS is 0.6 KHz and 3
KHz for voice. Having the two signals in this ratio
allows for CTS testing in the presence of voice.
Use of the CTS and EXTERNAL tone
sources work in a similiar manner as the CTS and
1 kHz. The CTS tone sets the same 5/1 ratio as in
the above example. An external input of 1 vp-p will
produce 3 KHz of deviation. Therefore a setting of
0.6 KHz CTS, with 1 vp-p external input will produce
3 KHz of deviation of the external tone.
3.12 OFFSET +/ OFFSET -
The Com 3 allows you to select any offset
frequency you desire. Enter in the desired offset
using the keyboard, then touch the STO key and
then touch the OFFSET+ key. This will store the
desired offset into the Com 3's memory. ‘Pressing
OFFSET+ or OFFSET- will increment or decrement
the display by the offset amount.
3.13 500Hz STEP
The two arrow keys are the 500Hz up or
down keys. Touching either of these keys will allow
you to step 500Hz at atime.
3.14 STORING/RECALLING TEST SETUPS
The Com 3 has the capability of storing up to 10
different test setups in its memory. Stored is the
current set-up selected on the Com 3's front panel,
including all frequencies being generated, CTS,
‘Offsets, etc. To store a test setup touch the STO
' key, then the number of where you want it stored
(0-9). To recall a setup, touch CLR, then RCL,
then the number of the memory you wish to recall
(0-9). |
3.15 SPURIOUS SIGNALS
in any wideband, receiver spurious signals
sometimes present problems. We would like to bring
to your attention the existance of a non-problematic
spur within the Com 3.
Refer to the block diagram. fig. 4.1) and the main
/ board schematic during the following explanation.
The Com 3 has a reference oscillator of 4 Mhz, the
fourth harmonic of this is 16 MHz. The first IF is from
14.5 to 16.5 MHz, and the second IF is 9.5 MHZ. As
you can see, if an incoming signal is at such a
frequency as to hit the first IF at 16 MHz, there
would be a possibility of interference or a
heterodyne due to the Com 3 receiving the forth
harmonic of its own reference oscillator. This will

Ramsey Electronics COM 3 Specifications

General

Brand	Ramsey Electronics
Model	COM 3
Category	Monitor
Language	English