[1000mp] Sound card interface

[Kok Chen]

Modes such as PSK31, MFSK16, DominoEX and Olivia requires you to use  
"AFSK," which is shown as "PKT" Mode on the FT-1000MP. You cannot use  
RTTY mode, which has no way for audio from the computer to modulate  
the transmitter.

You need three connections between the computer and the radio:

1) audio from the radio to the computer's input sound card that you  
have chosen,
2) audio to the radio from the computer's output sound card that you  
have chosen,
3) a method to key the PTT line.

All three functions are present in the PKT DIN connector of the 1000MP.

Unlike rigs such as the Elecraft K3, the VOX on the FT-1000MP does not  
function when set to AFSK ("PKT") mode, so you will have to be some  
way for the software to key the PTT line in the DIN connector.   
Although inconvenient, you can even use the MOX switch on the  
FT-1000MP each time you transmit.

The simplest way to adjust for correct drive levels on the FT-1000MP  
is to

(a) set the RF PWR to maximum (fully clockwise), then
(b) control the RF output power using the Mic Gain knob (this controls  
the AF drive of the audio in the PKT DIN connector) and
(c) -- this is important-- be sure that the ALC bars do not appear;  
not even a single bar.

One thing that you need to be careful about when you use the PKT mode,  
the transmit output from a FT-1000MP (I don't know about the Mark V)  
is not flat.  If you are using waterfall tuning and click on different  
parts of the waterfall, you need to be careful to check to make sure  
the the transmit power remains what you have chosen and the ALC  
remains off all the time.  The transmit power has a broad frequency  
peak (centered around the PKT tone pair that you have selected in the  
radio's Menu), but there is a few dB of difference between the peak  
and the edges of the audio passband.

Some software (like cocoaModem) has a transmit equalizer that will  
compensate for this uneven flatness in transmit power, so you  
calibrate the software once with your radio and need not do anything  
about it when operating.

Be sure to carefully bond the grounds of the 1000MP/computer/sound  
card together to avoid hum and noise from being transmitted and  
received.  If you cannot do that, use good quality audio transformers  
between the sound card and the radios to break any ground loops. Don't  
use cheap, small transformers since they can cause IM and harmonic  
distortion.

The FT-1000MP transmitter is moderately clean when ALC is not active.   
In PSK31, you can ask the other operator what the IMD of your  
transmitted PSK31 signal is -- most software has a means for  
displaying the received IMD.  When adjusted properly, the FT-1000MP is  
capable of better than -35 dB IMD (I get -40 dB when running 5 watts  
and below).  Try to do better than -25 dB IMD.  Anything worse than  
that and you will be causing QRM to nearby stations.

Be sure the peak RF output power does not clip.  When you are  
transmitting the idle PSK31 (transmitting but not typing anything) the  
PSK31 signal has a crest factor of 3 dB.  On the original FT-1000MP,  
make sure the power output never exceed 50 watts when you send an idle  
signal in PSK31.

73
Chen, W7AY