K4SB [hamcat@directvinternet.com] SAID to me
Well, I don't know if writelog does it, but if you just boot into
windows, you will find that RTS is Positive, and DTR is negative. Put
a voltmeter on the pin to ground to see it.
73
Ed
>From the RS232 Specs:
Interface Electrical
All signals are measured in reference to a common ground, which is called
the signal ground (AB). A positive voltage between 3 and 15 Vdc represents a
logical 0 and a negative voltage between 3 and 15 Vdc represents a logical
1.
This switching between positive and negative is called bipolar. The zero
state is not defined in RS232 and is considered a fault condition (this
happens when a device is turned off).
According to the above a maximum distance of 50 ft or 15 m. can be reached
at a maximum speed of 20k bps. This is according to the official
specifications, the distance can be exceeded with the use of Line
Drivers.Functional description
As you can see all signals use the same levels for logical one and zero and
MOST IMPORTANT the zero state is UNDEFINED. That means that you must live
with whatever you get when not running anything and THE PROGRAM must use
logical 0 to mean 1 and logical 1 to mean zero. Since almost all the radios
are set up using an NPN transistor with + into the base to key the radio so
that the output goes low means that he program has to reverse the logic. My
ports all have +12 when nothing is on them but they could just as well have
0 or minus 10 or whatever. This strange spec of the RS232 causes endless
confusion :-)
> -----Original Message-----
> From: writelog-admin@contesting.com
> [mailto:writelog-admin@contesting.com]On Behalf Of Steve Woodruff
> Sent: Sunday, November 10, 2002 12:04 AM
> To: writelog@contesting.com
> Subject: [WriteLog] ptt resistance (part 2)
>
>
> Ok - just when you thought this thread was dead.
> Using WL as my voice keyer... and as of last
> night i thought all was good. I changed the
> circuit to be 1k ohm into a 2n2222. When WL
> plays the ssb message, the rig trips into TX
> and back to RX after the message is done. Ok.
> Now today i tested it with the amp on. Oops.
> The amp goes into TX mode as soon as i turn
> it on -- and only goes off when i remove the
> PTT cord that i built for WriteLog (RTS from
> cw/serial port).
>
> I measure ~1450 ohms resistance when the PTT
> is *NOT* tripped -- its not enough to keep
> the ic706 in TX mode, but is that enough to
> trip the amp into TX? Maybe so. I will try
> to substitute a 2.2k ohm resistor for that
> 1k resistor and see if it helps. I did have
> a 4.7k resistor before -- but then i couldn't
> even get the rig to TX via this ptt line.
>
> any suggestions from those WL users who've
> gone through this before appreciated!
>
> tnx
>
> /steve n9oh
>
>
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