PSK31 and the battle of the sound card

Whilst I was over in Perth working with the VK6SAA special event station I was introduced to PSK31 as an operating mode. I had heard of PSK31 before but had never seen it in action, or cared that much to follow it up.

During the past 20 + years as a ham I have used many modes including RTTY, ATV, satellite, repeaters, IRLP, Echolink and packet just to name a few. But not PSK31.
So yesterday, whilst trying to stay cool in the middle of a heatwave, I did some research and read two articles by VK6PG, PSK31 THE EASY WAY and PSK31 THE EASY WAY – PART TWO.
I download two applications, HAMSCOPE and Digipan and installed them on my shack PC. I fashioned a quick connection between the PATCH input and AF output on the FT757 and my sound card.
After a bit of messing around I was able to decode a few signals but I seemed low in level and the waterfall and spectrum displays were quite lifeless.
I then found I had to have the overall volume in the sound card quite high (over 1/2) to get good indication and copy on the software. The level from the speakers however was too loud for comfortable listening. I don’t have separate volume controls on the speakers.
However when I try to transmit PSK31 the level going to the PATCH Input is way too strong and the radio sends well over 100 Watts and then cuts out. The only way to get it low is to decrease the wave volume and the overall volume to almost nothing. But with these settings the receive is poor.
I obviously need to build a better interface with individual level controls for RX and TX audio as well as adjustable speakers. Then, with some careful adjustment, I should be able to get everything sounding good.
I need to incorporate a PC controlled PTT as well as I was switching using the MOX button tonight. Whilst it works OK it is a pain to do. I tried using the VOX but the VOX is faulty on this FT-757 and it just locks on TX forever.
If all goes to plan I should have PSK31 working by mid next week.
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