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Re: [NA-User] Computer help

Subject: Re: [NA-User] Computer help
From: David Pruett <>
Date: Mon, 28 May 2007 10:46:58 -0400
List-post: <>

Based on Steve's note, I went and checked out and the 
interfaces he offers.  Doing rig control and CW keying on a single port 
is pretty straight forward, as the rig control uses the COM port's 
serial data pins (TXD & RXD) while the keying uses the control pins 
(DTR/RTS etc.).  But there are a couple of caveats that I want to explain.

THe K1NU interfaces are built into the shell of the COM port connector, 
making a compact and convenient package.  The rig control portion of the 
interface needs a power source for the level converter chip which 
converts the RS232 signal levels from the computer to the TTL levels the 
radios typically require.  Rather than having a wire coming out of the 
connector shell and requiring an external power source, the K1NU 
interface (and others like it from W1GEE, MFJ, etc.) require one of the 
COM port's pins to be turned on constantly to be used to power the level 
converter chip; in this case the RTS pin (pin 7 on a DB-9 COM port and 
pin 4 on a DB-25 COM port).

The caveat with this approach is that NA (and many of the other logging 
programs) use the RTS output to allow the computer to control 
transmit/receive, the advantage of which is that it can provide 
VOX-style T/R delay after sending (like your radio does) for manual 
(i.e. paddle) sending but no delay when the computer sends a canned message.

It's my feeling that most people don't use this feature, in which case 
the RTS port pin is asserted whenever NA is running and interfaces such 
as the K1NU should work fine.

The second caveat is that I've seen computers where the COM port cannot 
provide enough current out of the COM port pin to power the interface.

None of these comments are intended to be a criticism of the K1NU 
interface.  As I mentioned earlier, other companies utilize the same 
approach in their interfaces, and even the computer's mouse (if its a 
COM port mouse) uses a port pin for it's operating current.  However, 
these comments reflect the experiences I've had when using self-powered 
rig control interfaces at K8CC.

So to summarize, to successfully use self-powered radio control 
interfaces such as the K1NU:

- Make sure NA's CW PTT is set to NO in the Configuration Editor, 
CONFIG.EXE, F5 screen.

- If radio control does not seem to be working, check the voltage on the 
RTS pin (pin 7 on a DB-9, pin 4 on a DB-25) with the interface connected 
and NA running.  I'm not sure of the exact minimum voltage for the K1NU 
interface, but a good rule of thumb is that it should be 7 VDC minimum.



Steve Lufcy wrote:
> Joe-
> I bought a cable from that does both CW and rig control from one
> serial port. This actually works well from my windows 98 and 95 computers
> running NA. Irun NA from MSDOS, altho I do boot DOS from a window. This
> cable may solve your delima.
> 73 de KØOU Steve
> ----- Original Message ----- 
> From: <>
> To: <>
> Sent: Saturday, May 26, 2007 9:17 PM
> Subject: [NA-User] Computer help
>> Radio Dudes,
>> I have a dual-boot laptop (98 and XP). I boot to 98 and hit F8 to start
> from
>> a command prompt for running NA.
>> Problem: I only have one serial port and no parallel ports and I want  rig
>> control and keying control from the confuser. Any one have a similar set
> up
>> that you were able to accomplish both?
>> Ideas I have but don't know if they'll work:
>> 1) USB to serial port adapter (or parallel port adapter, if there  is such
> a
>> beast). (I don't know if the USB port and/or the  adapter would be "seen"
> by
>> the old OS)
>> 2) a PC-card (parallel port or serial port)
>> Thanks,  Joe
>> ************************************** See what's free at
>> _______________________________________________
>> NA-User mailing list
>> NA on the web:
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