PK232 From: WB2ZTK@WB2ZTK To: ALL@ALLBBS Hello Out there.... I've just completed my work on the PK 232. I mention earlier in the week of a problem with the PK 232 regarding RFI and how the 13 volt supply line is unprotected from accidentally placing voltages above 13.6 into that box. This 13.6 v line is connected to a couple of IC and branch to many transistors and is use as a pull up voltage for many circuits within the box. Well now that the highly stable voltage regulator in in place along with a RF choke of 20 uH. I can easly hear some of our checkins during the my Faxnet on 28.450. The RFI from that box was of the low level type and was knocking out the weak station when the unit was on. I am very happy with the addition for two reasons. 1. It protect the PK 232 from Murphy and I. 2. It gives my rig isolation from the RF that was leaking down the power supply leads to a common power supply shared with the rigs and other devices. For those that plan to add this protection, you'll find plenty of room inside the PK 232 to place this additonal Voltage reg. You might want to consider adding a bridge rectifier and 120 to 18 v @ 1 amp transformer, and connect the voltage regulator to that. I feel that the voltage regulator should be internally placed in the PK 232 along with the choke because of the leakage that was coming from the leads to a external supply. Some will find that placing ferride beads to help from this leakage, and keeping their external supply as is. Well some of us use power supplies that are ajustable and might apply voltages above 18v to the PK 232. The internal voltage regulator protects against this over voltage and choke blocks the RFI, this placement makes the best sense to me and thats how I went. Having fun and feeling safe, Dan... WB2ZTK... Are you having trouble with your PK-232 Locking up (not returning to receive mode) when a high RF signal is present? If so AEA says to add a .01 MFD Capacitor across D30. D30 is located in lower right hand corner of Main Board, parts pictorial page I-1 of operating manual, just to the left of JP2 and JP3 beside SW-2. I hope this helps, it stopped my problems ...... 73 Rick N7KQB @KE7PV ================================================================ PK-232 PROBLEM: TTL level transmit data is present on the FSKN and FSKR pins on J7 of the PK-232 regardless of the position of the RADIO 1/RADIO 2 switch. When left connected to the direct FSK keying inputs of many HF transcievers, the data on these lines will cause noise on the HF transmitted signal on other modes (SSB, FM, etc.) when the other port is being used on another radio. Further, to use direct FSK keying, one must split the interconnect cable at the PK-232 end because the receive audio and transmit FSKN/R signals use different connectors on the PK-232. SOLUTION: Select either the FSKN or FSKR signal (whichever you use) and substitute it for the SQUELCH input on J4 and J6. This allows the TTL level transmit data to appear on J4 and J6 pin 3 as selected by the RADIO 1/RADIO 2 switch. This eliminates both of the above problems. This modification requires no trace cuts or drills and may be easily restored. MODIFICATIONS: 1) Select the appropriate signal for your application. 2) Remove R150 3) Ground the base of Q6 using a jumper to the pad left by the Q6 side of R150. 4) Connect a jumper between the pad on the SW2 side of R150 and U38 pin 2 or pin 8 depending on your choice in step 1. NOTE: The pinouts on J7 for FSKN and FSKR are reversed at U38 on some PK-232 schematics. FSKN thus appears on U38 pin 8 and FSKR appears on U38 pin 2. The labels on J7 are correct. GOOD LUCK and 73, Rod NR7E @ W6PW-3 -=-=-=-=-=-=-=-=-=- These modifications apply to PK-232s with serial numbers under 1000. Four simple hardware modifications improve the PK-232's performance. 1. Change C54 from: 0.1 mfd 10% mylar (increase low-frequency rolloff) to: 0.01 mfd 10% mylar 2. Change U16 from: 74LS04 (do this only if bbRAM does NOT hold memory) to: 74HC14 3. Change R35 from 20K 5% (improve VHF/Morse sensitivity) to: 39K 5% 4. Add: 0.047mfd mylar 10% in series with R79 (same as above) ***Downloaded from compuserve 4/30/88 by KQ1K*** RELAYED BY...N0KGX...GENE -=-=-=-=-=-=-=- From: K4ON @ WB4GHL Subject: PK-232 Modification... The following might interest you (copied from K5FL MSO on RTTY): -=-=-=-=-=-=-=- The following information was received from Wolf, ZS6AQC, concerning new Eproms for the PK-232 PAKRATT, plus a modification to eliminate noise from the op-amps. On recommendation of OM Piet, ZS6AQC I checked the noise in the power bus to the MC34074P op-amps and found (just like he said) that there is a lot of rubbish between the pins 4 and 11 of U23, 26, 28, 30, 32 and 34. So I placed some 1 microFarad caps across them and my receive noise is much less (measured on a mark=space scope cross display). In fact, I can now even copy some steady signals that don't even raise the S-meter needle. Hope you can improve yours also? This was received from OD5NG: he made this mod and resulsts were outstanding. Then Clark, W9CD made the modification and was pleased with the results. Consequently, I bought from Radio Shack 6 each 1 MF tantalum capacitors ("condensers" to Old Timers), and mounted them on the bottom of the board, with the shortest possible leads in the positions described above. The results are OUTSTANDING!!! RTTY signals I could not copy before are now perfect copy, even when you can barely see the traces on the scope. ARQ links, which could not be made before, now flow smoothly. The only thing I don't know if the mod will work if the latest version of the PK232 firmware upgrade is not installed, but I would think that it will. Give it a try and you will be pleasantly surprised. 73 AND GL de John, TG9VT! ............. RELAYED BY...N0KGX...GENE -=-=-=-=-=-=-=-=- There is a bug in the latest version (1.06) of the AEA PC Pakratt program for use with IBM PC or compatible computers. If you attempt change the packet parameter SQUELCH at the parameter window from the default value of NEG to POS, the program will abort and give you the error message: RS-232 link error - will reinitialize - Press ESC and after pressing Escape, the program will try to re-establish a link with the PK-232 and present the message: Parameter download error Please refer to your PC-PAKRATT manual. Program terminating. Unfortunately, the parameter download error message isn't mentioned anywhere in the manual. This bug apparently does not present a problem to the vast majority of PK-232 users. It need not concern you if: you have NOT connected the squelch signal line between your transceiver and the PK-232 (pin 3 of the RADIO 1 and RADIO 2 interface connectors), or if you have made the connection, lucky enough to own a transceiver that provides the correct signal sense to the PK-232 for the proper operation of RF-carrier CSMA with the program default value of NEG for the SQUELCH parameter. The bug is exhibited when the program incorrectly attempts to send the command SQUELCH POS to the PK-232. With release 25 June 1987 firmware, allowed values for the SQUELCH parameter are ON, OFF, or NEG. The value POS causes the PK-232 to return an error code to the program, which then abruptly crashes. Fortunately, the fix for this bug is simple. It is only necessary to change the program to send the allowable values for the SQUELCH parameter to the PK-232. The patch below will replace the program values of NEG and POS with OFF and ON respectively. Using the DOS debug utility, enter the following: debug utilmod.chn -e 614c 20 4f 4e -e 6160 4f 46 46 -e 6174 20 4f 4e -w -q After spending a number of hours building some very nice interface cables, I was frustrated to think that I may of had to modify them to cope with a program bug. AEA is aware of the problem, but they have not yet corrected it. I'm glad that I was able to come up with a reasonable fix, and hope that this information proves useful to someone else. See you on the digital modes! David J. Buress AD4B Alexandria, VA -=-=-=-=-=-=-=-=- From: VE7FRY@VE7KIT To: ALL@ALLBBS Subject: pk232 fix and mod 1. The PK-232 will cause ssb and fm distortion when plugged in to a TS- 680 (aux port). My fix has been to add a 470 pF. Hi-Q disk cap. in series with the TX-audio line, and leave the mic gain at maximum. I also have the 600 ohm divider resis- tor (R 151 radio 1) lifted but don't know if it still helps after the cap mod. 2. When switching from Com-Fax to Com- Pakratt cartridges the RTTY Rx-after -Tx key F7 is disabled. The fix is to enter Terminal mode on Com- Pakratt ( t) and then enter conmode converse. 3. I have received mods to convert the PK-232 into a dual-port tnc for gateway dual-rig use from VE7DIE @ VE7DIE. Drop him a note if inter- ested. -=-=-=-=-=-=-=-=-=- Through personal experiences with the PK-232, I have found that a somewhat strange problem seems to have been isolated. I had recently had some difficulty with the PTT not holding solidly on transmit. It seemed almost attributable to the buffer/data flow into the unit, as the problem seemed to lessen in severity when the threshold adjustment was increased so the unit could not transmit; then by backing it off, it would send a packet stream without incident. By accident almost, I finally decided to drop the input voltage to the TNC (which had been fed by 14.5 volts -- sharing a common power supply as the transceiver). This immediately cleared the "chatter" problem. Apparently, the 232 uses the input voltage in a number of places, one of which is in the PTT control circuit. Unlike the 5 volt stages, the 13 volt supply is NOT regulated and thus whatever the input voltage is, that's what the "13+ volt" bus would be. If anyone has similar problems with the PK232, it would seem that you have 3 choices: 1. Buy an AEA or similar transformer to supply fixed 12.6 volts to the unit. 2. Drop your power supply voltage to this point and sacrifice a little bit of power/performance from your transceiver 3. Put in a separate 12 volt regulator circuit for the 232 separately. I hope this has been of help for anyone who may have incurred similar difficulties. --Gary, WH6C -=-=-=-=-=-=- From: WA2AAR@WA2AAR To: ALL@ALLBBS IN ADTION TO WB2ZTK'S NOTE ON MSG. #329 ABT THE INTERALLY UNREGULATED SUPPLY, THIS CAUSES ADDITIONAL PROBLEMS. IF OTHER RELETIVELY HIGH POWER EQUIPMENT IS TURNED ON OR OFF, THE RESULTANT "GLITCH" ON THE AC LINE COULD AND HAS CAUSED THE PK-232 TO "LOSE ITS MIND" REQUIRING THAT IT BE TURNED OFF FOR A SHORT WHILE (NO INTERNAL BATTS), TURN IT ON AND HV PC-PACKRATT RE-INITIALIZE EVERYTHING. (A PAIN) THIS HAPPENS WHEN I INADVERTENTLY OPEN OR SHUT-OFF MY IC-735 PLUGGED INTO THE SAME LINE (117VAC) AS THE PWR FOR THE PK-232. IT DOESNT ALWAYS HV THIS EFFECT, LEADING ME TO BELIEVE THAT IT DEPENDS WHERE THE AC LINE WAVEFORM HAPPENS TO BE ALONE IN ITS CYCLE WHEN THE PWR SWITCH IS USED. IF THE WAVEFORM IS NEAR ITS ZERO CROSSING OR AT A LEVEL THAT IS LIKELY TO CAUSE THE LEAST AMOUNT OF INDUCTIVE KICKBACK FROM THE PWR. TRANSFORMER TO PROPAGATE. TO CAUSE PROBLEMS THE 12V REG. THAT DAN SUGGESTS WITH A 13V INPUT OR EVEN TWO 15V ZENER DIODES BACK TO BACK WITH A 100uf ELECTOLYTIC CAP IS WHAT I USE IN PARALLEL WITH MY SUPPLY NOW WITH GOOD RESULTS. THE BEST PLACE TO PUT IT IS IN THE TNC'S CABINET OR AT LEAST AS NEAR AS POSSIBLE TO IT EXTERNALLY. *** QRU FOR NOW DE N2HRJ TONY *** -=-=-=-=-=-=-=-=- All users with PK-232's and PK-87's can use the MBX command in the following manner with the NET/ROM nodes. Normally, MBX call1 monitors packets being sent by "call1", such as from a BBS, etc. MBX call1, call2 monitors just text being exchanged between those two stations. (Presumably it should also prevent other packets from being included which were being sent to other stations, but for some reason other packets find their way to the display with W6IXU multibox.) With the NET/ROM nodes going up, here's some info for using MBX for proper monitoring: If the user is local and going to another user with just the one local node, use local-15, remote. For instance, WB6WKB is using the node W6AMT-3 to get to WB6SAN, the node will be using WB6WKB-15 to talk to WB6SAN. The MBX should be set to WB6WKB-15,WB6SAN. If WB6WKB is talking up the network to someone else, use the node's callsign instead, since it's whom WB6WKB is actually talking to. In this case, set MBX WB6WKB,W6AMT-3 (assuming W6AMT-3 is the node involved and WB6WKB is visible to you). Internode exchanges and transmissions from the node to other stations are not shown. It's the next best thing to being the connectee! MBX does not work on two callsigns which are not connected to each other, so you can't follow two BBS's simultaneously. Otherwise, I've found it very useful, many times saving me the hassle of having to connect to read the newest messages or to download the latest Pathefinder or Gateway. -=-=-=-=-=-=-=- ----RECEIVED FROM W3GL AMTOR MAILBOX----- JANUARY 6, 1988, RECEIVED 01/07/88 AT 05:54 UTC - DE AD4B THERE IS A BUG IN THE LATEST VERSION (1.06) OF THE AEA PC PAKRATT PROGRAM FOR USE WITH IBM PC OR COMPATIBLE COMPUTERS. IF YOU ATTEMPT TO CHANGE THE PACKET PARAMETER SQUELCH AT THE PARAMETER WINDOW FROM THE DEFAULT VALUE OF NEG TO POS, THE PROGRAM WILL ABORT AND GIVE YOU THE ERROR MESSAGE: . RS-232 LINK ERROR - WILL REINITIALIZE - PRESS ESC . AND AFTER PRESSING ESCAPE, THE PROGRAM WILL TRY TO RE-ESTABLISH A LINK WITH THE PK-232 AND PRESENT THE MESSAGE: . PARAMETER DOWNLOAD ERROR PLEASE REFER TO YOUR PC-PAKRATT MANUAL. PROGRAM TERMINATING. . UNFORTUNATELY, THE PARAMETER DOWNLOAD ERROR MESSAGE ISNT MENTIONED ANYWHERE IN THE MANUAL. THIS BUG APPARENTLY DOES NOT PRESENT A PROBLEM TO THE VAST MAJORITY OF PK-232 USERS. IT NEED NOT CONCERN YOU IF: YOU HAVE NOT CONNECTED THE SQUELCH SIGNAL LINE BETWEEN YOUR TRANSCEIVER AND THE PK-232 (PIN 3 OF THE RADIO 1 AND RADIO 2 INTERFACE CONNECTORS), OR IF YOU HAVE MADE THE CONNECTION, LUCKY ENOUGH TO OWN A TRANSCEIVER THAT PROVIDES THE CORRECT SIGNAL SENSE TO THE PK-232 FOR THE PROPER OPERATION OF RF-CARRIER CSMA WITH THE PROGRAM DEFAULT VALUE OF NEG FOR THE SQUELCH PARAMETER. . THE BUG IS EXHIBITED WHEN THE PROGRAM INCORRECTLY ATTEMPTS TO SEND THE COMMAND SQUELCH POS TO THE PK-232. WITH RELEASE 25 JUNE 1987 FIRMWARE, ALLOWED VALUES FOR THE SQUELCH PARAMETER ARE ON, OFF, OR NEG. THE VALUE POS CAUSES THE PK-232 TO RETURN AN ERROR CODE TO THE PROGRAM, WHICH THEN ABRUPTLY CRASHES. . FORTUNATELY, THE FIX FOR THIS BUG IS SIMPLE. IT IS ONLY NECESSARY TO CHANGE THE PROGRAM TO SEND THE ALLOWABLE VALUES FOR THE SQUELCH PARAMETER TO THE PK-232. THE PATCH BELOW WILL REPLACE THE PROGRAM VALUES OF NEG AND POS WITH OFF AND ON RESPECTIVELY. . USING THE DOS DEBUG UTILITY, ENTER THE FOLLOWING: . DEBUG UTILMOD.CHN -E 614C 20 4F 4E -E 6160 4F 46 46 -E 6174 20 4F 4E -W -Q AFTER SPENDING A NUMBER OF HOURS BUILDING SOME VERY NICE INTERFACE CABLES, I WAS FRUSTRATED TO THINK THAT I MAY OF HAD TO MODIFY THEM TO COPE WITH A PROGRAM BUG. AEA IS AWARE OF THE PROBLEM, BUT THEY HAVE NOT YET CORRECTED IT. I'M GLAD THAT I WAS ABLE TO COME UP WITH A REASONABLE FIX, AND HOPE THAT THIS INFORMATION PROVES USEFUL TO SOMEONE ELSE. . SEE YOU ON THE DIGITAL MODES? . DAVID J. BURESS AD4B -=-=-=-=-=-=- CONTINUED IN FILE PK232-1