De : EB2AQH A : PK232 @EU Tipo/status : B$ Fecha/hora : 20-Dic 02:11z Bid : 22_EB2AQH Mensaje # : 156425 Titulo : Problem with FSK Path: !EA3RDG!EA3RAC!EA3ET!F6DSP!F6FBB!F6GGY!F1ONT!F8KKA!F5RJI!F8KOP!F6KBN! !F8REF!F6DEG!F5KAR!GB7SXE!GB7ICE!GB7HSN!GB7DAA!LWBBBS!GB7LWB!GB7COV! !GB7OGY!GB7AYI!GB7BAD!GB7WRG!GB7CYM!GB7MSF!EA7AFG!EA4PE!EB4DHE!EA4CJJ! !EA1FEL!EA2RCP!EA2URV! From: EB2AQH@EA2URV.EABI.ESP.EU To : PK232@EU [EB2AQH/TPK 1.82 Msg:22 Dia:30-11-94 Hora:16:24 Z 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 requiees 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. ============ FIN MSG# 156425 ============ De : EB2AQH A : PK232 @EU Tipo/status : BX Fecha/hora : 23-Dic 06:03z Bid : 20_EB2AQH Mensaje # : 156812 Titulo : Cooling Mod for PK232 MBX Path: !EA7UH!EA7URS!EB4EKN!EA6XQ!EA4BKP!EA4CRS!EA4PE!EB4DHE!EA4CJJ!EA1FEL! !EA2RCP!EA2URV! From: EB2AQH@EA2URV.EABI.ESP.EU To : PK232@EU [EB2AQH/TPK 1.82 Msg:20 Dia:30-11-94 Hora:16:21 Z "Cooling" Mod for the PK232 MBX by Tom, AB5FH AB5FH @ N5LJF.#AUS.TX.USA.NA 23 July 1992 (REVISED) For all PK232 MBX owners, place your hand on the top, middle, right side of the PK232 case. If it appears warm-to-hot after one hour of operation, read on. The power voltage regulator/heatsink is mounted to the circuit board below this point. This regulator is an LM317T voltage regulator capable of dissipating approximately 15 watts. In normal packet mode, this regulator sources approximately 700 milliamps with a voltage drop (across the LM317T) of approximately 6.7 volts. This results in a power dissipation for the LM317T of approximately 4.7 watts. While this is 1/3 of the capability of the LM317T, this heat is driven into the circuit board. While replacing a defective radio selector switch, I noticed that the circuit board under the heat sink was charred. This particular PK 232 MBX has been in operation approximately 3 years. A review of the schematic revealed that there was no series dropping resistor in series with the LM317T input. This resistor is used to reduce the input voltage to the LM317T which in turn reduces the voltage drop across regulator. With this voltage reduction, the power dissipation of the device is reduced. I paralleled two 10 ohm, 2 watt resistors and placed them in series with the cathode of D11. This reduced the dissipation power of the LM317T by approximately 30%. Consequenty, the entire unit runs exceptionally cooler with no degradation in performance. The heat will be dissipated by the resistors (instead of the LM317T) and then be conducted into the case. The two paralleled resistors were placed adjacent to the heat sink, and along the edge of the circuit board. These resistor should be installed so that they are at least 1/4" above the circuit board. You can make this mod from the top of the board since the circuit board trace to this resistor is on the top side and the hole feedthru is plated thru the board. Locate and lift up diode D11(large bodied diode closest to the side edge of the board near the LM317T regulator.) from the cathode side (banded end). Use a low wattage iron and wick soldlead. The resistor lead that is to be placed in that hole must be trimmed so that no more than 1/16" of lead extends from the underside of the board. If you are uncomfortable with this step, you may remove the circuit board to expose the underside of the board. Place one lead of the paralleled resistor assembly in that hole and solder in place. Be sure that the resistor pair sits above the circuit board. It helps to let the resistors lay over on their while they are soldered in place. This will force the pair to be sit above the board. Position the other lead end of the resistor pair such that it connects to the cathode (band end) of diode D11. Solder the resistor lead to the DII diode lead. Position the resistor pair so that their leads are not in contact with the LM317T heatsink or the 1000 ufd filter capacitor (C26). The resistor pair was obtained from Radio Shack (part no. 271-080 - $.99) and that was done to my PK232 MBX is optional due to its aesthetic result. A pattern of 8 holes (0.1" in dia) were drilled in the cover above the heat sink and resistor pair. With the holes drilled in the case top, there is no noticeable heat rise detected on the cover and no degradation in performance in all modes. I have operated the modified unit for over 2 weeks since the modification without disconnecting power with no degradation in performance It is also important to note that the AEA transformer supplied to power the PK 232 outputs DC voltage in excess of 17 volts unloaded. This can be checked by placing a meter on the connector end of the transformer unit while it is plugged in. When connected to the PK232, the load of the PK232 MBX drops this voltage to approximately 13 volts (nominal). If you have a newer PK232MBX (> s/n 50000 and with multicolored LED's), you will have a 7805 regulator in place of the LM317T. This fix still applies to the 7805 regulator circuit. ============ FIN MSG# 156812 ============ De : EB2AQH A : PK232 @EU Tipo/status : BX Fecha/hora : 14-Dic 23:10z Bid : 19_EB2AQH Mensaje # : 154615 Titulo : PK232 MODS Path: !EA7UH!EA4PO!EB4EKN!EA6XQ!EA4BKP!EA4CRS!EB4BFL!EA4BPO!EA4PE!EB4DHE! !EA4CJJ!EA1FEL!EA2RCP!EA2URV! From: EB2AQH@EA2URV.EABI.ESP.EU To : PK232@EU [EB2AQH/TPK 1.82 Msg:19 Dia:30-11-94 Hora:16:18 Z From: G4UXD@GB7OAR Subject: PK-232 Lockup Cures Dear Reader! There was such a response to my note regarding "Cures for PK232 Lockup" that I've had to put out a general bulletin! Here is a synopsis of some of the replies I got to my Help! cry: Lenny (the sysop @GB7LIV) reported that he ended up putting 0.01 uF disc ceramic capacitors between ALL connections to the radio (232 also? Derek) and ground. He also fitted a heavy braided earth strap from the chassis of the TNC to TRUE earth (onto the earth chassis of the computer or to an earth point on a 13 amp socket outlet). The problem then stopped TOTALLY. Chris (G6FCI @ GB7FCI) reported a problem with his PK232 locking up when a fluorescent light (and other appliances sometimes) was turned to spikes getting onto the earths in the RS232 between the computer and TNC. Heto solve it and is not quite sure which effected a cure. 1) Stick a decoupling cap between the RTS and CTS lines and earth (he thinks that was where he put them). 2) Strap the signal and frame ground lines together at the TNC and computer end of the RS232 cable. He knows that technically the two are supposed to be separate, but suspects that the problem arises when the signal ground ends up at a different potential from the frame ground. He hasn't had the TNC lock up for 6 months or more. Alex (G1FBY @ GB7BMX) reported that he has had his 232 for two years. One of the first problems he encountered was lockup. All investigations of the unit proved OK. One Sunday his XYL was using the washing machine and dishwasher for long periods of time and the PK232 locked up 6 times. It was run on a fully regulated power supply. He fitted a Radio Spares spike protection socket to the mains plug of the power supply and all has been FB since. ********************** Hope this is useful, 73 de Derek [G4UXD @ GB7OAR] Copied from the QRZ! Windows Ham Radio CDROM ============ FIN MSG# 154615 ============ 3:EA7MU BBS 19:45 Horas. (A,B,C,D,F,G,H,I,J,K,L,N,O,R,S,T,U,V,W,X,Y,?) >