Msg Nr. : 32407 Da : LU7AKC Per : NET9K6@WW Tipo/status : B$ Data/ora : 0815/0249 Dimensione : 7597 Titolo : TS790 & 9600 Bps Bid (Mid) : 12270_LU7AKC TS-790 & G3RUH. KENWOOD TS-790E 4800 baud operation. These notes tell you where to get FM RX audio direct from the discriminator, and where to modulate the FM TX directly. ACC4 CONNECTOR Two pins in the ACC4 connector are free to use: pin 3 and pin 5, pin 8 is ptt and pin 2 is ground. Remove the bottom cover only. You can now see the IF-unit. Remove all screws and place the unit in vertical position. Now you can reach the solder-side. TX connection 1. Locate ACC4 = CN38. 2. Take a piece of shielded cable, solder the inner to ACC4 pin 5 and the outer to ACC4 pin 2 (ground). 3. Locate CN31. Solder the inner of the shielded cable to pin 2 (use ferrit) and don't connect the shield at this side. RX connection 1. Locate ACC4 = CN38. 2. Take a piece of shielded cable, solder the inner to ACC4 pin 3 and the outer to ACC4 pin 2 (ground). 3. Locate IC 8 (MC3357P) on the IF-unit. Take a 10 uF tant. capacitor and a 8k2 resistor. Solder the + to pin 9 and the - to one end of the resistor. Solder the other end of the 8k2 resistor to the ground. Now connect the inner of the shielded cable to the junction of the capacitor and the resistor. Don't connect the outer. Put the IF-unit back in place. Be sure that all the smal coaxial connectors are still in place on IF-unit ! Now you can connect the moden to the TS790E with the 7-pins ACC4 connector supplied with the tranceiver. At this time I only have tested this on 70 cm but this must also work on 2 meter and 23 cm. Send remarks and/or suggestions to my home-bbs. Succes! 73's, Bern PE1ABT @ PI8TMA or PI8UTR ADAPTING THE KENWOOD TS-790A FOR USE WITH THE PACCOMM MC-NB96 G3RUH MODEM 12-26-91 The Kenwood TS-790A makes a wonderful 9600 BPS Packet Radio Transceiver as it has an excellent front end, powerful transmitter, and 144,440, and 1.2 GHZ coverage. The CFW-455F filter inside is not too narrow despite what you may have read and coupled with the low noise front end of the rig enables the G3RUH modem to reliably decode valid data that barely moves the S-meter. The modification discribed below is simple, reversible, and does not impair normal operation or the appearance of the transceiver. This is a "no holes" modification as it allows the G3RUH modem to be connected to ACC 4 jack on the rear panel. Place the TS-790A upside down on a soft clean surface so as not to mar the cabinet. Remove the bottom cover to expose the IF. Board. With the front panel facing you the work area is the upper left quarter of the IF board. Identify pin 9 of IC8 (MC3357P). There are two of these chips on the IF board but only the main demodulator IC is in the work area. RX audio to the modem will be derived from this point. Next locate J31 a two pin connector near D81 and X2 (10.965 OSC). TX audio from the modem will be supplied to the hot lead on J31. Note the large aluminum heat sink that spans across the IF board near the rear of the chassis. A round lug will be mounted on it near the rear of ACC 4 jack. Wire an eight pin din plug. Use shielded cable for TX and RX audio. No traces on the IF board need to be cut. Pins 3 and 5 of ACC 4 are not connected to anything as the radio comes from the factory. Make sure the Din plug fits the jack properly before wiring it. PIN 2 - ground PIN 3 - TX audio from G3RUH PIN 5 - RX audio to G3RUH PIN 8 - PTT Prepare two six inch lenghts of RG-174. Prepare one end of each cable so that the shield will reach the ground lug mounted on the large aluminum heat sink. The cables will be routed over the top of the heat sink and will not be crushe when the bottom cover is reinstalled as there is adequate clearance. Solder the center conductor of one cable to pin 3 on the rear of ACC 4 (verif with ohm meter). Solder the center conductor of the other cable to pin 5 on the rear of ACC4 (verify with ohm meter). Dress the cable connected to ACC 4 pin 5 over to IC8 pin 9. Cut to size and solder (be careful- use minimum heat and thin solder). The exposed shield is discarded and heat shrink tubing place over the end to prevent any shorts that would otherwise occur from having exposed strands of the shield touching something. Dress the other cable connected to pin 3 of ACC 4 to J31 and cut to size. Prepare the end in the sam manner as the other cable. Solder the center conductor to pin 2 of J31. This i accomplished by cutting the lead going to pin 2 about 1/2 inch back, stripping the insulation back 1/8 inch on the two ends, and then joining the center conductor of the cable going to pin 3 of ACC 4 and soldering the three exposed ends together. Use heat shrink tubing to cover the solder joint. NOTE that the banded end of D81 is not the cathode of the varactor diode ! There is no need to insert any additional capacitance in series with J31 pin 2 The shields are not connected at both ends of the RG-174 cables in order to prevent ground loops. The Aluminum heat sink was used as ground as no other ground was available that was close to ACC 4. Your sight may be better than mind and you may find one. Adjust VR-1 on the MC-NB96 board for 75 mv p-p as measured on pin 2 of J31. This will give a good initial setting for injected transmit audio lewel. This completes the modification. 9600 BPS Packet can now be enjoyed on each of the bands installed in your TS-790A. For non-packet operation either unplug the modem from ACC 4 or turn off power to the modem. For 9600 packet operation unplug the mic and turn the mic gain to minimum. Thanks to Frank Anderson, W7ZTA and Jeff Angus, WA6FWI for their help. Please report any errors or suggestions to: Mike Hooper KF6PU @ WB6YMH.#SOCA ******************************************************************************** ADAPTING THE KENWOOD TS-790A FOR USE WITH THE PACCOMM MC-NB96 G3RUH MODEM 12-26-91 The Kenwood TS-790A makes a wonderful 9600 BPS Packet Radio Transceiver as it has an excellent front end, powerful transmitter, and 144,440, and 1.2 GHZ coverage. The CFW-455F filter inside is not too narrow despite what you may have read and coupled with the low noise front end of the rig enables the G3RUH modem to reliably decode valid data that barely moves the S-meter. The modification discribed below is simple, reversible, and does not impair normal operation or the appearance of the transceiver. This is a "no holes" modification as it allows the G3RUH modem to be connected to ACC 4 jack on the rear panel. Place the TS-790A upside down on a soft clean surface so as not to mar the cabinet. Remove the bottom cover to expose the IF. Board. With the front panel facing you the work area is the upper left quarter of the IF board. Identify pin 9 of IC8 (MC3357P). There are two of these chips on the IF board but only the main demodulator IC is in the work area. RX audio to the modem will be derived from this point. Next locate J31 a two pin connector near D81 and X2 (10.965 OSC). TX audio from the modem will be supplied to the hot lead on J31. Note the large aluminum heat sink that spans across the IF board near the rear of the chassis. A round lug will be mounted on it near the rear of ACC 4 jack. Wire an eight pin din plug. Use shielded cable for TX and RX audio. No traces on the IF board need to be cut. Pins 3 and 5 of ACC 4 are not connected to anything as the radio comes from the factory. Make sure the Din plug fits the jack properly before wiring it. PIN 2 - ground PIN 3 - TX audio from G3RUH PIN 5 - RX audio to G3RUH PIN 8 - PTT Prepare two six inch lenghts of RG-174. Prepare one end of each cable so that the shield will reach the ground lug mounted on the large aluminum heat sink. The cables will be routed over the top of the heat sink and will not be crushed when the bottom cover is reinstalled as there is adequate clearance. Solder the center conductor of one cable to pin 3 on the rear of ACC 4 (verify with ohm meter). Solder the center conductor of the other cable to pin 5 on the rear of ACC4 (verify with ohm meter). Dress the cable connected to ACC 4 pin 5 over to IC8 pin 9. Cut to size and solder (be careful- use minimum heat and thin solder). The exposed shield is discarded and heat shrink tubing placed over the end to prevent any shorts that would otherwise occur from having exposed strands of the shield touching something. Dress the other cable connected to pin 3 of ACC 4 to J31 and cut to size. Prepare the end in the same manner as the other cable. Solder the center conductor to pin 2 of J31. This is accomplished by cutting the lead going to pin 2 about 1/2 inch back, stripping the insulation back 1/8 inch on the two ends, and then joining the center conductor of the cable going to pin 3 of ACC 4 and soldering the three exposed ends together. Use heat shrink tubing to cover the solder joint. NOTE that the banded end of D81 is not the cathode of the varactor diode ! There is no need to insert any additional capacitance in series with J31 pin 2. The shields are not connected at both ends of the RG-174 cables in order to prevent ground loops. The Aluminum heat sink was used as ground as no other ground was available that was close to ACC 4. Your sight may be better than mind and you may find one. Adjust VR-1 on the MC-NB96 board for 75 mv p-p as measured on pin 2 of J31. This will give a good initial setting for injected transmit audio level. This completes the modification. 9600 BPS Packet can now be enjoyed on each of the bands installed in your TS-790A. For non-packet operation either unplug the modem from ACC 4 or turn off power to the modem. For 9600 packet operation unplug the mic and turn the mic gain to minimum. Thanks to Frank Anderson, W7ZTA and Jeff Angus, WA6FWI for their help. Please report any errors or suggestions to: Mike Hooper KF6PU @ WB6YMH.#SOCA ***************************************************************************** TS790 mods.for G3RUH/TAPR-PSK ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This short note is addressed to Paul DU1POL originaly, but it may be help of them who has the same problem,I uploaded addressed To:All here. -------------- Hello Paul G3RUH 9.6kbps modem connection need mod. to both TX and RX. of 790. TX..... connect new 1kohm R to the point D81 and R358(1k ohm) OR connect to CONNECTOR-31 directly. RX..... IC8(MC3357P)---for main RX, IC1(MC3357P)---for sub RX pin #9 is the point to draw RX signal. Usualy, sub RX is used for satellite communication as TX/RX freq. is different. But I drew both main and sub signal and switch them with a microrelay.This relay can be controled with main panel SW 144ATT.(see 790 manual). These mods. are essential for G3RUH 9.6kbps, but also usable for FO-20 PSK. BUT.....with my experience, there is many trouble to use this mods. for TAPR PSK modem. TX audio level setting, RX noise (MC3357P pin#9 has 455khz wave element).....and so on. So, I use ACC2 for TAPR PSK modem (also usable for 1200AFSK) -------------- ACC2 connection 4---GND 9---PTT 11---TXD audio signal in 1 --3.3k---\ 3 --3.3k---/ connect together to RX audio. two small 1/8w 3.3k regitor mixes main and sub audio, so it is able to use for cross band full duplex and mono band half duplex operation. These registor can be mounted in ACC2 13 pin plug. -------------- UP/DWN control from TAPR PSK modem to 790 U12 and JP5/6 setting U12 790 mic terminal pin 8 ---- D ------ UP pin 4 pin 5 ---- E ------ DWN pin 3 G --- B ------ GND line pin 6 and pin 7 must be jumpered and connect to ground. * R75 2.7kohm may be changed to 300-500ohm for steady photo couple. * C32, C34 (10uF) must be changed to 3.3uF or 4.7uF for rapid doppler shift tracking. * R7 in TX audio output circuit must be changed to 2.2Kohm as the original have heavy phase distortion. With this change, TX audio connection to mic (or ACC2) is no problem (no need dirct varactor feeding). -------------- Mods. to audio drop problem in 790 computer control. In computer control from rear ACC1 terminal,frequency setting command makes 10m sec.of audio drop(mute),and data collapse occur in PACKET operation. This problem is fixed by killing the blanking pulse to IF amp circuit. remove Q4(2SC2712) on IF unit and short the collector circuit to GND (R15 470 ohm). This mods. is essential for auto freq. control with KCT/Tuner for low orbit Packet satellite. This is all of my mods. to 790/G3RUH/TAPR-PSK modem Best regards. Sueo Asato JA6FTL ******************************************************************************