[Lowfer] HELP.. I Need A Relay Keyed By Computer

[Cliff Sojourner]

hi Andy,

the standard, common in most ham radio software that I have seen, seems 
to be use a serial port, RTS (line 7), to control TX.

connect the base of a small signal NPN, like 2n3904 or 2n2222, through a 
resistor, like 1k.  emitter to +12v, collector to the relay coil, to 
ground.  put a reverse biased diode such as 1n4148 across the relay coil 
terminals to eat the back EMF, instead of destroying the transistor.

depending on the RS-232 interface, you may have to ground the base of 
the NPN through a 2k resistor to get it to shut off reliably.

easy & simple.  the most difficult part may be driving the serial port 
RTS line.  what software are you using?

and, does the radio have a CAT or C-IV interface?  connect the serial 
port RXD and TXD lines to the radio's interface.

Cliff K6CLS

On 2013-05-06 20:27, Andy - KU4XR wrote:
> Hi all:
>
> I need a simple " something " to use the serial port to engage a
> relay that will be used to key my radio.. I have been keying by
> VOX up till this point, but the rig has never been happy doing
> that..AND; for it to work, I have to use a bonding wire between
> the case of the computer, and the rig chassis or all it will do
> is sit there and chatter the VOX relay.. Pressing the send button
> and all works fine.. The problem with the bonding wire is that
> it causes almost 2 S-units of computer hash in the receiver when
> I connect it to the radio.. I would think that a computer keyed
> relay could be used to key the radio " Without " a direct bond
> between the computer and the rig, thus hopefully eliminating the
> noise problem, and the rig keying issues at the same time..
> Thank for any advise on the subject..
>
> 73: - Andy - KU4XR
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