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

[DAVE PICK]

Andy

An opto-coupler would do it without coupling the earths.

Dave


On 7 May 2013 06:36, Cliff Sojourner <cls at employees.org> wrote:

> 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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