KAM INSTALLATION of the TAPR DCD STATE MACHINE UPGRADE for KANTRONICS KAM. 1. BROWN Solder to the pad marked "X" near the top edge of the KAM'S board, near U25 by R96. 2. RED Solder to the outer one of the pads of C53 near the top edge of the KAM'S board. 3. ORANGE *** NOT USED *** 4. YELLOW On the top of the KAM'S board inbetween U26 and R104 you will see the 20 pins of K8. Turn the board over and trace from pin 21 of U26 (63B03X) to pins 7 and 8 of K8 and cut the circuit between 7 and 8. Then turn the board back over and solder the YELLOW wire to the pin of K8 that will lead back to pin 21 of U26. 5. GREEN *** NOT USED *** 6. BLUE Inbetween U5 and U2 solder to the end of R29 closest to U26 7. VIOLET Solder to the pad on the top of the KAM'S board inbetween R103 and RLY1. 8. GRAY You will find 2 pads on top of board inbetween U26 and U2, solder to the pad closest to pin 1 of U26. If you prefer not to view the RCV LED on the front of the KAM (which will be on continuous) then cut the circuit that leads to L4 on the bottom of the board. Put the DCD Upgrade JMP across pins 2 and 3. White and Black wires were removed, not used. Works Great! de KA9UEX RELAYED BY N0KGX...GENE ------------- Subject: KAM Voltage Problem I received a new KAM for Christmas and when I hooked it up it was very weird acting. I had trouble getting my call in it, wrong letters would show up the keyboard was sluggish, I had to turn the 8bitconv off and change line settings on the terminal program to make a half way contact. I called the factory and excellent help was immediately given. The problem was too much voltage on the RS 232 Serial Line. It likes to see 12 volts. The new wall supplies were causing the problem. The older 12 volt supplies were 300 ma the new supplies are 500 ma and the KAM uses about 300 ma with the voltage being about 14.5 volts going into the KAM. I measured the DVE supply, a 12 volt 500 ma and it was putting out over 19 volts unloaded, about 14.27 to 14.7 volts into the KAM on. It was suggested I clip the plug off the wall supply and tie it to the stations supply. Since I run 13.8 volts there I instead inserted a Radio Shack 12 volt regulator IC in series near the KAM with a .3 ufd cap on the input and output as suggested and PRESTO all problems solved. I was able to turn the 8bitconv on, use 1200 baud, no parity, 8bits with 1 stop bit, all as suggested and everything is working great. I must say the first two evening I had my doubts, but now I in total love with the KAM and the help from Kantronics is fast and friendly Dave K0RWM-7 and can be reached at K0BOY BBS in Omaha. ---------- Subject: KAM Audio Modification I have experienced problems using a KAM with the TR78xx series of transmitters. The problem was due to overdriving of the audio from the KAM LO outout which is about 10 mv p-p. While this worked OK on the older TR7400 rig it caused many repeats and time-outs with the 7800,7830 and 7850. The change is as follows.. Replace R11 on the KAM board with a 200-500 miniature multu-turn pot and with the help of another station with a VU meter set the pot for a level of zero DB or to the same level as a reference station in your area. The approximate level for the KAM audio out is about 3 mv but you may find minor differences. Having trouble getting your KAM to key your transmitter on CW? I hooked up mine to a Uniden HR-2600 and found it would not key the rig. So here's a easy mod which I received directly from Karl Medcalf at Kantronics: Bypass resistor R-107. Check your KAM manual for the location. It's near the connector end of the TNC, close to the DB25 connector. You can solder a jumper wire across the resistor on either side of the board. Modification works great! 73, Andy/K4ADL @N4QQ.MD.USA.NA --------------- ..CONNECTING THE DATA ENGINE TO YOUR COMPUTER.. Just a word of caution, when wiring the "DE, 8-pin plug, to the computer DB-25 pins" page 5. The DE 8 pin plug as shown, is "Reverse". It should be shown from 8 to 1, instead of 1 to 8, top to bottom. " C O R R E C T W I R I N G" _________________________________________________________ DE purpose computer color pin DB-25 pins 8 DSR 6 white 7 DCD 8 brown 6 DTR 20 yellow 5 SG 7 green 4 RD 3 red 3 TD 2 black 2 CTS 5 orange 1 RTS 4 blue ___________________________________________________________ This applies with DATA ENGINE tnc's starting with serial no. 850 Kantronics also confirmed this, and has since rectified the problem. When the wiring was redone, the TNC worked properly without any flaws up to 9600 baud, TNC to COMPUTER. Just thouth I'd tell you guys, who have intention of buying Kam's new "BEAST" hi!!! 73's Jean, ve2ed @ve2ed ar, --------+----- I have noted the following bug in the KAM: With Battery backup installed and MAXUSERS at 0/0, if the power fails and is restored, the KAM will come up with MAXUSERS 1/1. If you now set it back to 0/0 manually (or by sending the command automatically) the next power failure will result in the KAM crashing totally, losing all parameters including the callsign. This has been verified with two KAM's both running V2.84 firmware. 73 de Dave VE1EI ----++---- The AM/FM push-button switch on a KAM panel (S2) changes not only compression rate of the input amplifier system (U1-14, Q5 and Q6) but signal input sensitivity. Reduction of the first is desired for a CW reception to avoid "swamping" of the circuitry (over-compressing); however, the second effect could create a problem in interfacing with a transceiver. I use ICOM-751 transceiver and feed the KAM from high impedance output (10 kohm) before AF gain control and power amplifier (pin 4 of 24-pin lug). Since the impedance of KAM audio input is only 600 ohms, the signal is much attenuated. To develop the required 20 mVpp on the input pin for non-CW reception (the switch in FM position), the transceiver has to output 0.35 Vpp (20*10600/600). But, if the switch is in AM position, the de-sensitized input (about 100 mVpp) requires at lest 1.8 Vpp. This value, which is close to distortion limit of the transceiver, I could obtain with strong signals and with disconnected AGC (in OFF) only. I have slightly modified the KAM circuitry by disconnecting the AM/FM switch from ground and connecting this point to the R1-R13 junction. The switch changes rate of compression only. The sensitivity of AF input remains constant at 20 mVpp. Now, I could: - copy very weak CW signals which hardly move the S-meter, - use large dynamic range of the transceiver automatic gain control and enjoy easiness and speed of tuning to a CW station. This is how I understand the circuit. Sorry for the long text. You could skip it. The original circuit: If signal level at U1-14 exceeds 0.6 V in peak, the transistor (Q5) starts feeding the FET transistor (Q6). The FET by-passed by R27 and with series R13 acts as a variable attenuation pad (voltage divider). Timing of this AGC (or compression) is determined by R19-C10 (2.2 ms attack) and R21-C1 (1 s release), and this is independent of AM/FM switch position. Since an op-amp (U1-14) has amplification of 100, peak voltage at its positive input pin is not much higher than 6 mV (12 mVpp). Diodes CR4 and CR5 are inoperative in this low range of voltages. They protect the KAM circuitry against large voltage, which could be accidentally applied to the input. Only the FET (Q6) fulfils a function of the gain control. When the AM/FM switch is off, the attenuating pad (R13-Q6) works in a range 1 to 1000 (0 dB to 60 dB according to the specification). When the switch is on, the initial attenuatiom is 7.7 and the controlling feedback is much reduced. Modified circuit: When R27 by-passes R13 (instead of Q6 as in original cct), the initial attenuation remains the same (=1), but attenuation ability in reduced. The circuitry treats the signal with more "respect". The compressor is not "over-doing" its function. Actual modification: 1. Cut the PCB track which grounds the AM/FM switch as close as possible to the switch, 2. Connect this cut-off switch pin to junction R1-R13 with thin wire-wrap wire. The modification works well not only for me; Art, VE3RX modified his KAM and is satisfied with its results. I will be glad hearing your opinion: VE3MRM @ VE3NUU (BBS) on 145.03 MHz or VE3MRM-1 (my PBBS) on 145.59 MHz both in Toronto. Enjoy and 73 ---+++--- I have seen and heard many complains about the KAM and KPC2, waiting to long before retying a packet. I had the same problem and phoned the factory about it. They kind of suggest that there is no problem, but also tell you to set the following commands. DW 0 PERSIST 192/63 for the KAM and 63 for the KPC2, SLOTTIME 5/10 fr the KAM and 10 for the KPC2, TXDELAY 30. Well, that didn't realy help a lot. Looking on page 47 and 48 of the KAM manual or page 36 and 37 of the KPC2 manual, you will find that for re-transmisions of the **same** packet, the wait time equals to: Wait time = (DWait+r*TXDelay)*10 milliseconds where r is a random number from 0 to 15. That would mean that the maximum wait time would be 4 1/2 seconds. And it will wait this long **after** the channel is clear before trying to retransmit the packet. The problem seems to be that if the channel gets busy before this time is passed, the whole thing starts all over again. It is called a collision- avoidence strategy in the manual. Does it ever work. The station on the receiving end will time out, clearing the frequency for the rest of us. Now here is the solution for the KPC2 and the VHF port on the KAM. From the above equation we see that the dalay is mainly due to TXDelay, because DWAIT would be set at 0 if we use SLottime and PERSsist. What you do is set TXDelay to 10 and make the difference up with AXDelay 20. That will give you a total of 300 milliseconds of time for the transmitter to key up and the receiver at the other end to open its squelch. If you need more time, just increase AXDelay. Also set SLottime to 5 and PERSist to 10 (yes, ten) in this case. This only works for the VHF section of the KAM and for the KPC2. There is no AXDelay on the HF section of the KAM. On the HF port on the KAM, I have SLottime at 5 and PERSist at 255 with DWait set at 0 and TXDelay at 40. If you add a 27K resistor across R47 on the bottom of the board if you like, it will speed up the carrier detect. Now make sure that the carrier detect led goes off between monitored packets. Do this by turning the audio down. The manual suggests not to have more than 200 mVolt going into the KAM. This will let the KAM copy better, including ACKs. That means less retrys. And a final suggestion. If you use the KAM as HF RLI type BBS, you might consider setting CHeck to 6 (six) and the timeout timer in the BBS program to 600 or higher. This way the KAM will time out the BBS if no packets moved, instead of having the BBS time out while the KAM is still trying to move the packets from its very large buffer. On VHF you might try CHeck 24. This would work for other units as well. I use the KAM on 14.107 and it seems to work very well this way. Let me know if this works for you like it does for me. Oh yes, I use version 2.85 in both units. 73 Nand ve3iwj @ ve3iwj. ---+++--- I have experienced problems using a KAM with the TR78xx series of transmitters. The problem was due to overdriving of the audio from the KAM LO outout which is about 10 mv p-p. While this worked OK on the older TR7400 rig it caused many repeats and time-outs with the 7800,7830 and 7850. The change is as follows.. Replace R11 on the KAM board with a 200-500 miniature multu-turn pot and with the help of another station with a VU meter set the pot for a level of zero DB or to the same level as a reference station in your area.The approximate level for the KAM audio out is about 3 mv but you may find minor differences. 73 .. Fred @ VE3NUU. ------------ I read the suggestion by Fred about the internal mod for the KAM to reduce the AFSK audio output level. I took another approach which also works well. Rather than terminating the TNC to radio cord with the appropriate mic plug for the rig, i put a 5 pin male din connector on instead. Then I made up a patch cord for each radio with a 5 pin female din connector on one end and the mic connector on the other. Inside the back shell of the patch cord din plug I've placed an attenuation network made up of 1/4 watt resistors that matches the AFSK level to that needed by the rig. Since each rig has its own patch cord, the level is set automatically when the cord is selected. I used an A.F. millivoltmeter and a deviation meter to determine the values of the resistors needed for each case by comparing the deviation resulting from using the rigs mic to that produced by the TNC. This way there is no need to alter the TNC and you can change rigs without having to make any adjustments after they have been initially determined. 73, Weazle, VE3EAR @ VE3WZL. --------- I noticed that the KAM, when connected or trying to connect, will start to transmit on top of an other signal at times. This will happen when a received signal appears just before the the KAM wants to transmit. It is visible by looking at the mark/space display. After a quiet period a received signal will light up the bargraph display and the KAM will transmit on top of it. Looking at the circuit diagram, I noticed a 1 uF capacitor (c 29) in the carrier detect circuit. It seems to slow down the detect function more than desired. Changing the capacitor to .1 uF made the carrier detect work more the way I expect it to. It is easy to get at. Somewhere in the middle of the board. There is a layout in the manual. I didn't ask Kantronics about it. And I didn't notice any side effects. I also didn't try it in any of the other modes. Comment to ve3iwj @ ve3iwj. 73 Nand. ==------== From: WA1YTW @ W1FYR.NH.USA.NA AS MANY KNOW THAT HAVE TRIED TO GET THE REVERSE FORWARD TO WORK, IT DOES NOT! THE PROBLEM? WHEN THE KAM SENDS ITS BBS ID, IT IS MISSING A "$"...AND POSSIBLY NOT IN THE RIGHT PLACE. THE FIX: ENTER INTO PTEXT THE FOLLOWING: [KAM-3.03-H$] IF YOUR TNC IS A KAM. ...IF NOT ENTER THE SAME MESSAGE YOURS HAS WITH THE $ ADDED AS ABOVE. 73 SCOTT WA1YTW @ W1FYR.NH.USA.NA --==++==-- PORTED AND REALIGNED FROM PC TO AMIGA FORMAT BY BOB G0LBQ - N6XDI.