Sub: Hooking the PK-232 MBX to the TS690S or the TS450S and grounding the PK-232 to reduce distortion on SSB transmissions. I would like to take this opportunity to thank everyone who replied to my question about connecting the PK-232 to the TS690S. I eventually had to replace Q5 and the PK-232 now keys the 690S. In particular, I would like to thank Dick (KD5VU) and Erich (KA6AMD) for their input on how to connect the PK-232 to the 690S and the 450S. The following information has been edited from that which they had sent me earlier. 1. HOOKUP AND PIN ASSIGNMENTS Dick uses the ACCY2 port of the 450S to hook up his PK-232 for AFSK operation. The following list details the Pin Assignments which Dick uses for AFSK Operation: PK-232 J4 TS-450S (ACCY2 PORT) Pin 5 RED PTT Pin 9 PTT Pin 4 BROWN GND Pin 8 GND (Do not use Pins 4 or 12) Pin 3 BLACK - - Not Used Pin 2 WHITE AFSK-OUT Pin 11 AFSK-IN Pin 1 GREEN AFSK-IN Pin 3 AFSK-OUT As Dick indicated to me, it is important to ensure that you do not overdrive the rig. Since neither the 690S or the 450S has a Tx monitor you will need to watch the ALC setting after setting the desired power level and AFSK audio output from the PK-232. Please note that it takes very little Mic Gain to overdrive the ALC. Also - the 450S and the 690S are rated as 100% duty cycle units. I personally felt more comfortable setting the power level to 50 - 75 watts although the 690S manual suggests setting the power level to 100 watts. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Erich (KA6AMD) hooked up his 690S to the PK-232 in order to use FSK for digital communications. The hookup he uses works well for him on all the digital modes and is listed below: PK-232 TS690S (ACCY2) J7-4 FSK KEYING 2 J4-1 Rx AUDIO 3 J4-4 AUDIO GROUND 4 J7-2 FSK AUDIO 8 J4-5 PTT 9 J4-2 Tx AUDIO 11 On the PK-232 J4 is Radio Port 1. J6 is Radio Port 2. Either port may be used. 2. GROUNDING PROBLEMS Both Erich and Dick indicated that they had distortion when transmitting on SSB when the PK-232 was hooked to their rigs. The Kenwood reps were not able to help them with regards to the problem. Erich suggested that I Disconnect the PK-232 when using SSB. Dick also had little luck with the reps, but he was able to determine that there are floating grounds in the ACCY2 port of the 450S and 690S. Dick appears to have corrected this problem by grounding the PK-232 to the 450S. As Dick noted (edited :-))(please note that Dick is using AFSK): > " Yes! I had the SAME problem (I called it distorted xmit audio) and > the GROUNDING fixed the problem. Its history and the rig works now > with the PK-232 hooked up via the ACCY2 plug. The fine print > in the (Ken)wood manual says you have to GROUND the rig. You better > ground it as they have some floating grounds. > > > I grounded the PK-232 to the Kenwood TS-450S/AT two ways: > > - Used the single pin 8 in the ACCY2 plug to the Gnd connector > on the PK-232 (the white molex plug). Note I did not [repeat > did not] used pins 4 & 12 as shown in the TS-450S manual. > > - The winner was to ground the PK-232 from the circuit board (used > one of the screws that supports the mounting foot nearest the > DC imput connector) to the Large Ground Lug on the rear of the > TS-450S. > > > Kenwood has some floating grounds in the ACCY2 port and will not > admit to the problem. > > Without the REAL ground wire PK-232 to TS-450S my SSB audio was > big time screwed up when the ACCY2 plug was attache. " I have set my rig up for AFSK operation and I have grounded my TS690S as Dick has suggested. I have not yet had problems with my audio when transmitting on SSB. Once again - Thanks to all who replied. And as Erich noted earlier: ANYTHING YOU TRY WITH YOUR TNC (PK-232) AND YOUR RADIOS IS YOUR RESPONSIBILITY. 73 DAVE VY2DCS, SEELER@UPEI.CA