3 August 94 from Gould Smith, WA4SXM with much thanks to Mark Shepard, ZL1TRE I HAVE NOT TESTED THESE MODS - PROCEED AT YOUR OWN RISK!! 9600 bps mods included: KENWOOD TM531 TR751E TR851E TS-700A TS711 & TS811 TS-790 ****************************************************************************** TS-790 with serial frequency control ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ by Kohjin Yamada, JR1EDE 3 Jun'90 This note is the summary of our discussion made among W9FMW, JA6FTL and myself. The first report has been brought by WB0KSL expressing TS-790 has audio drops at the frequency change command in it's serial control. JA6FTL confirmed the data loss at the product detecter on his scope too. These are as terrible as if we use KCT Tuner in it's serial control option. Kenwood replied to my inquiry "It is made as so to prevent the noise of PLL, about 100m sec mute is created". Kenwood suggests the modification as below but it should be made on user's responsibility. This should be solved in their next products, I strongly told them. JA6FTL and I confirmed that it now works perfectly on FO-20's actual test and uSATs too with the following modification. Kenwood suggestion; (Refer to IF DIAGRAM) ~~~~~~~~~~~~~~~~~~~ You could disable the mute function by following methods, both or item 2 only. 1) Delete D20 or R191 (for SUB audio) As far as you would use the rear data port (ACC2), it's *NOT* necessary to do this, although you would still have the audio drop at the sound of loud speaker. Of cource, you should do this modification when you would hook up the audio data from Microphone Plug. 2) Put a jumper between Q4 collector and emitter (for SUB RF Block) This modification is a *MUST*. You can do this by several ways but the above is most easy. The following discussion might help you a bit; (partly eddited by me) I wrote to W9FMW; >Cut the line between Q4 Collector and R15 (470 orhm) and Ground the end of >R15. JA6FTL made the mod removing Q4 entirelly and grounding the end of R15. >Q4 located the left of Q5, they are located roughly oposite side of L2, L3. >JA6FTL says the modification needs a magnifying glass, Hi. There is 1 Reply. #: 18154 S5/Amateur Satellites 01-Jun-90 09:08:20 Sb: #18148-TS790 mod for KCT Fm: Sueo Asato JA6FTL 71701,251 To: Kohjin Yamada, JR1EDE 76662,111 Here is additional info. to the modification. Yes..... Need magnifying glass (I am not farsighted nor shortsighted Hi.) This modification is to disable the blocking line for IF amp. Audio muting function remains unchanged, but it is no problem to use rear data port. (Audio muting circuit consists of D20 and Q12) 1.Put the frontside toward you and remove the bottom cover of 790. 2.remove the 13 screws that fix IF board. Lift over up the board toward you. 3.Q5 and Q4 are located just opposite side of L2 and L3. Chip Q5(printed "V11") has 4 solderd legs, and it's located next to R15 (470 ohm surface mount resistor, printed as "471"). Q4 is located just beside R15 and has 3 legs. *************************************************************************** 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. [1200 baud PSK birds only] This is all of my mods. to 790/G3RUH/TAPR-PSK modem Best regards. Sueo Asato JA6FTL EOF ========================================================= From : IT9DLN To : ALL Title : TS790 NO MUTING Keywords : MODS TS790 FOR KCT/T TRAKBOX Uploader : IT9DLN Uploaded : Tue Aug 11 21:39:39 1992 __________________________ Hello OM, This mods. is essential for auto freq. control with KCT/T TRAKBOX way RS232 ACC1 terminal TS790E no muting SUB audio product: This modification is to disable audio muting, remove R191 on IF UNIT, resistor located R191 under connector-21 pin 7 sabk . Me running magnifying after mods. no muting on TS790 with KCT/T way ACC1. To prove to believe hi Good Luck 73 Santo Buttafuoco Butera IT9DLN via Aristotile 3 (0925-74707) ====================================================== MsgNo: 52623 From: JE1RLA@JA1WOI Date: 22-Apr/05:31 Subject: G3RUH modem <-> TM531(to PE1KHX) Times Read: 1 The terminal is connected to slider of VR3(Max. deviation adjast) through through C55(1uf). You can discriminate the terminal of VCO from VR3. TXA ----/\/\/\--II---------- MO VCO 56kohm 0.1uF If you get weary to remove a shielding plate, you may connect TXA to hotend of VR3 through R and C as aforesaid. 2. RXA connect to pin 12 of IC2. IC2 is a hybrid IC for FM IF amp. and detector. The IC was not indicated the number of pin. You must discriminate the pin from granded pin of IC. 2 and 16(last) pin is connected to grand. I connect 2 TNCs to this tranceiver. One is 9600bps and oter is Bell 202,1200bps. Tow modems are running without any troubles. Sammy JE1RLA @je1rla =============================================================================== Hello, Ed. I received your mail today morning,on Dec., 15. I'm using TM-531 on G3RUH type 9600bps modem. We ha local aria network using 9600bps modem. It is working well,now. But, beginning of this network is not easy. You can connect G3RUH type modem as follow. 1. TXA Take off the shielding plate under the main PCB. Search for VR3 on main PCB. VR3 is indicated on PCB "MAX DEV" for adjust maximum deviation. The slider of this VR is connected to MD pin of VCO through C55 capacitor. Connect TXA to MD pin of VCO using resister(56k to 100kohm) and capacitor 0.1uF,connected in series,like follow. TXA ---II------/\/\/\----MD(VCO) 0.1uF 56k to 100kohm If you get weary to take off shielding plate,you may connect the TXA to hot end of VR3, using the resister and capacitor as aforesaid. 2. RXA Search for IC2 on main PCB. IC2 is a 16 pin hybrid IC for IF AMP and discriminator. You can discriminate pin number of this IC from printed symbol on the main PCB, and grand pin. Pin 2 and 16 is connected to grand. pin 5 is output for ceramic filter(CF1),and pin 7 is input from the filter. Connect RXA to pin 12(DET) directly. 9600bps on 1200MHz band is very difficult. Because,frequency stability is not enough. And, IF band width is not enough,too. We are developing SMC transceiver for G3RUH modem on 144,430,1200MHz band. It has high stability PLL OSC(about 1ppm) and good linearity @ modulator (voltage controlled X'tal OSC) Sammy JE1RLA @ JE1RLA =============================================================================== I use the TS-790 with an LL Grace DSP-12 TNC/Modem. Three mods were required to use the 790 with the 9600 bps birds. These are: 1) Receive audio must come from the descriminator. 2) Transmit audio must bypass all filtering and pre-emphasis. 3) Receive audio muting must be disabled. The third item is especially troublesome. Kenwood chose to mute the output audio for a few dozen milliseconds whenever the receive frequency is changed. As I recall, their reason was to mute PLL noise, or something like that. This makes life difficult for anyone trying to tune the radio for doppler shift while copying digital satellites. The muting punches holes in the data. I can provide detailed info on these three mods to anyone that needs it. 73, John Brooks, KC4YMR Internet: kc4ymr@amsat.org or: johnbrooks@attmail.com Packet: KC4YMR @ WB4D.VA.USA.NA