Hook_Up information for Yaesu FT-736R and Pac-Comm PSK-1
To get perfect tones and proper deviation.

        I have had difficulty accessing the Pacsats and FO-20 using a Yaesu FT-736R and the Pac-Comm PSK-1. Through research, calls to Pac-Comm and some experimenting I have developed this solution. It works for me and should for other 736 users. 
        However, please remember that any mods done to your radio are at your own risk and I assume no responsibility or guarantee of success of this mod. I only know it worked for me.
        This hook up scheme wires the TX audio from the PSK-1 directly to the FM varactor, similarly to what is published in the Pac-Comm PSK-1 owners manual. The difference is that this works.
        I could not get the hook-up as described in the owners manual to work. The main reason is as follows.
        The PSK-1 manual (or at least the one I have) lists JP-4 as the audio level jumper. This is incorrect, it is JP-5 and JP-5 must be closed by the jumper to be used in this mod. This jumper raises the amount of audio output quite a bit but still not enough for my taste.
        The suggestion in the manual to hook the audio in at the R32 will not work. You are feeding thru a 10K resistor and cutting the audio down again  The best place to hook in is to CAREFULLY solder the PSK-1 audio lead to the right hand side of R33. R33 is a 15K resistor to the left of R32 and between two transistors and a cap.
        Be VERY careful and use a long nosed soldering iron or pencil as you are very close to several other components. Again you solder to the right hand end (with the front of the radio to you) of R33. The ground and shield of the audio cable can be connected to the shield enclosure near by.
        Run the cable out of the radio and hook into the PSK-1.
        Now you must make a couple of mods to the PSK-1. Open it up and find R40. It is a 5K pot that adjust the TX audio output. It is the one that can be adjusted from the back panel of the PSK-1. Change this to a 10K pot of the same type or a 20K will work if you don't have a 10K (I used a 20K). Next find R41 and change it to a 14 or 15K resistor.
Pac-Comm suggested that on R41 do not use a 13K or less resistor.
        All of this will increase the TX audio output to where you can modulate the 736 at 3 to 3.5 KHZ deviation with no problem. 
        As to setting the deviation I suggest you find some one that has a service monitor and set it at 3 KHZ. I guess you could set it by ear, but I don't recommend that.
        The 736 apparently needs quite a bit of audio to drive the varactor directly in this manner. So, this is what I had to do. Prior to this I had great trouble accessing the Pacsats and FO-20 cause of the impure tones after the filters in the radio hammered on them.
        I can now access FO-20 easily and I hope to logon to the Pacsats as soon as they come back up.
        I get the RX audio from the data jack on the back of the 736 as per the 736 manual.
        I hope this will help someone who also has pulled their hair out on this and logging onto the little birds.

Paul Gilbert, KE5ZW, 70416,1634