Page 11
Construction Manual for the K2DI v.III and K2DI-PCI boards © EA3BLQ - Revision June 2005
In this way pin 1 will render a square wave signal whenever there is an AF signal fed to pin
2. In the absence of such an AF signal the output will be 0 (zero) volts.
Because of this, whenever there is an AF signal fed to pin 2, the 1N4148 (D3) diode
rectifies the square wave signal present at pin 1 and charges the C5 capacitor at 5 vDC.
The values of the conjunct R7 and C5 determine the time constant, when the capacitor will
remain charged.
While C5 is charged, the second section (U2 b) will render 5 vDC on its outlet at pin 7.
When, because there is no AF signal at pin 2, C5 gets discharged, there will be 0 (zero)
volts present at pin 7.
The tension present at pin 7, through R5 biases Q1 which emitter and collector become
conductive and drive the PTT switch by grounding pin 3 at P1.
Pins 2 and 3 at J4 as well as those of J3 must be jumpered.
Soundcard isolation
The soundcard’s Line In/Mic and Line Out/Spk are isolated from the circuit by a couple of
600:600 Ω audio coupling transformers by Atech Technology Co. Ltd., the ATS-075, which
offers a very flat response and a very low profile.
AF In level
So as not to overdrive the transmitter and to prevent IMD, the level of the audio fed to the
K2 for transmission may be set by means of the 10K trimmer potentiometer R2.
CAUTION:
• If and when using the VOX (Tone) PTT option, care must be taken to mute, at
your OS, all the sounds and chimes scheduled to announce Windows’ and other
program’s events or happenings (Start -> Configuration -> Control Panel ->
Sound, Audio and Voice Devices -> Change Sound Scheme -> Properties ->
Sound). It is MOST IMPORTANT that no unwanted sound is produced. Otherwise,
those sounds will inadvertently trigger the PTT and, to our own despair and
annoyance or what is more embarrassing, to that of the contacted remote station
or the listeners, the unwanted sound will be transmitted.
• If your Sound Card has the full duplex feature, when setting the Sound Card
Mixer, remember to mute the Line In or Microphone In at the Sound Level
Control, so that the received audio or noise is not echoed to the Line Out outlet
and thus get the PTT switched On continuously.
(160 Seiten)
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Kommentare zu diesen Handbüchern