RS232 problems with KPA100
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Greetings, all you I/O experts out there -- I need some advice, please....
I'm using K2 #2634 with a KPA100 and KAT100; therefore the RS232 I/O is done by the MAX1406 chip on the KPA100. I've done computer control in the past but not for some months, so today I was rather surprised when I went to try out a new CAT program and could not get it to control or read out from the K2/KPA100. A breakout box showed no signal coming from the KPA100, and the TXD line from the computer indicated signals until I connected the KPA100; then the line seemed to be dragged down almost to 0v by the KPA100. After verifying continuity between the computer end of the RS232 cable and the RF chokes on the KPA100 board (RFC6, RFC7) I meaured voltages on the MAX1406 chip. Except for the 5 and 12v supply voltages they were not what the chart in the manual described. The pin voltages on the MAX1406/U4 chip were: 1 - +12.54 2 - -0.43 3 - -0.03 4 - -0.43 5 - -0.44 6 - 0.44 7 - -0.44 8 - -5.87 9 - 0.00 10 - 0.00 11- 0.10 12 - -0.13 13 - -0.09 14 - 0.00 15- -0.09 16 - 4.96 The voltage on pin 8 (-5.87) is at the very low end of the expected -5 to -25v range shown on the schematic, and even the +30v on the HV bias supply is low at 19.54v --almost as though whatever is wrong in the chip is dragging down the -25v and and the rest of the HV bias. Resistance on the TXD/RXD leads at the chip is about 100 ohms to ground with the power removed. All measurements made with a FLUKE 87 DMM. I don't know how but I'm afraid I've somehow crisped the MAX1406. Is there anything else I should try before replacing the chip??? TIA, all Van, W1WCG _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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The high voltage bias supply on the KIO2 is between -6v to -12, so
your 19.4 is probably sufficient, but the KIO2 Vss, U4 pin 8 is -9v on my KIO2. The MAX1406 wants from -13.2 to -10.8, but the absolute max ratings are from +0.3 to -14.0, so you're probably OK with the -5.87. The real suspect is that U4 pin 12 should be reading +5V from the AUXBUS on the control board. The only other use of AUXBUS on the KPA100 is U1 pin 28 (RB7 Serial Programming Data). It would be worth checking out AUXBUX line for a short (C25) or an open P1 pin 1. On Sat, 25 Jun 2005 16:06:46 -0400, "Frank Van Cleef W1WCG" <[hidden email]> wrote: >Greetings, all you I/O experts out there -- I need some advice, please.... > >I'm using K2 #2634 with a KPA100 and KAT100; therefore the RS232 I/O is done by the MAX1406 chip on the KPA100. I've done computer control in the past but not for some months, so today I was rather surprised when I went to try out a new CAT program and could not get it to control or read out from the K2/KPA100. A breakout box showed no signal coming from the KPA100, and the TXD line from the computer indicated signals until I connected the KPA100; then the line seemed to be dragged down almost to 0v by the KPA100. > >After verifying continuity between the computer end of the RS232 cable and the RF chokes on the KPA100 board (RFC6, RFC7) I meaured voltages on the MAX1406 chip. Except for the 5 and 12v supply voltages they were not what the chart in the manual described. The pin voltages on the MAX1406/U4 chip were: > > 1 - +12.54 2 - -0.43 3 - -0.03 4 - -0.43 > 5 - -0.44 6 - 0.44 7 - -0.44 8 - -5.87 > 9 - 0.00 10 - 0.00 11- 0.10 12 - -0.13 > 13 - -0.09 14 - 0.00 15- -0.09 16 - 4.96 > >The voltage on pin 8 (-5.87) is at the very low end of the expected -5 to -25v range shown on the schematic, and even the +30v on the HV bias supply is low at 19.54v --almost as though whatever is wrong in the chip is dragging >down the -25v and and the rest of the HV bias. > >Resistance on the TXD/RXD leads at the chip is about 100 ohms to ground with the power removed. >All measurements made with a FLUKE 87 DMM. > >I don't know how but I'm afraid I've somehow crisped the MAX1406. Is there anything else I should try before replacing the chip??? > >TIA, all > >Van, W1WCG >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Van W1WCG
Frank,
Can you make a comparison of the voltage on U4 pin 8 with what you had at some time previous. All other voltages except that one seem in order with no computer connected. The only pins used on the chip are 1, 5, 6, 8, 11, 12, and 16. Pins 9 10 and 14 are grounded, but the rest are floating. You may be correct that the negative supply is being dragged down, but I know of no way to confirm that except by removing U4. Yes, the reduced negative supply voltage should be resolved because that will cause improper T/R switch operation at higher power levels. The KPA100 should function normally with U4 removed (except that you will have no computer interface function). Your assumption that U4 may be toast may indeed turn out to be correct, but I really can't tell from the info I have right now. I did see another note on the reflector indicating that you may want to look at the AUXBUS line - that signal does not appear on U4 and is not a part of the RS-232 function. If you hear relays click in the KPA100, the AUXBUS is working. 73, Don W3FPR > -----Original Message----- > > Greetings, all you I/O experts out there -- I need some advice, please.... > > I'm using K2 #2634 with a KPA100 and KAT100; therefore the RS232 > I/O is done by the MAX1406 chip on the KPA100. I've done > computer control in the past but not for some months, so today I > was rather surprised when I went to try out a new CAT program and > could not get it to control or read out from the K2/KPA100. A > breakout box showed no signal coming from the KPA100, and the TXD > line from the computer indicated signals until I connected the > KPA100; then the line seemed to be dragged down almost to 0v by > the KPA100. > > After verifying continuity between the computer end of the RS232 > cable and the RF chokes on the KPA100 board (RFC6, RFC7) I > meaured voltages on the MAX1406 chip. Except for the 5 and 12v > supply voltages they were not what the chart in the manual > described. The pin voltages on the MAX1406/U4 chip were: > > 1 - +12.54 2 - -0.43 3 - -0.03 > 4 - -0.43 > 5 - -0.44 6 - 0.44 7 - -0.44 > 8 - -5.87 > 9 - 0.00 10 - 0.00 11- 0.10 > 12 - -0.13 > 13 - -0.09 14 - 0.00 15- -0.09 > 16 - 4.96 > > The voltage on pin 8 (-5.87) is at the very low end of the > expected -5 to -25v range shown on the schematic, and even the > +30v on the HV bias supply is low at 19.54v --almost as though > whatever is wrong in the chip is dragging > down the -25v and and the rest of the HV bias. > > Resistance on the TXD/RXD leads at the chip is about 100 ohms to > ground with the power removed. > All measurements made with a FLUKE 87 DMM. > > I don't know how but I'm afraid I've somehow crisped the MAX1406. > Is there anything else I should try before replacing the chip??? > > No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.8.1/28 - Release Date: 6/24/2005 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Matt Osborn
On Jun 25, 2005, at 5:02 PM, Matt Osborn wrote: > The high voltage bias supply on the KIO2 is between -6v to -12, so > your 19.4 is probably sufficient, but the KIO2 Vss, U4 pin 8 is -9v on > my KIO2. The MAX1406 wants from -13.2 to -10.8, but the absolute max > ratings are from +0.3 to -14.0, so you're probably OK with the -5.87. I would expect the supply to be a bit more robust in the KPA100 than in the KIO2 because of differences in the circuit. Still, the supply is in the range I have seen in many KRC2 units, and should work just fine. Note that the KIO2 and KRC2 use the same FET-based circuit for the negative supply, while the KPA uses a bipolar transistor circuit which also develops a larger bias supply for the amplifier. The KPA circuit has much greater current capacity. Having said that, for the KPA tthose voltages are relatively low, and may be a clue. Does the amplifier work properly? If so, then this is probably not the problem. But... (see below). > The real suspect is that U4 pin 12 should be reading +5V from the > AUXBUS on the control board. The only other use of AUXBUS on the > KPA100 is U1 pin 28 (RB7 Serial Programming Data). > It would be worth checking out AUXBUX line for a short (C25) or an > open P1 pin 1. If the Auxbus line were being shorted, the entire radio would not work, but would show an IO error. Unless this is being seen, the Auxbus is just fine. Also, just as a hint, the Auxbus is not used for device programming anywhere in the K2/100. It _is_ a bussed signal, and if it is shorted in any connected module (like the KPA100) it will cause the entire Auxbus to go silent (and the K2 to show an error message). > On Sat, 25 Jun 2005 16:06:46 -0400, "Frank Van Cleef W1WCG" > <[hidden email]> wrote: >> After verifying continuity between the computer end of the RS232 >> cable and the RF chokes on the KPA100 board (RFC6, RFC7) I meaured >> voltages on the MAX1406 chip. But did you verify continuity between the computer end and the MAX1406? The RF chokes are the primary items to worry about in case of "blown" interface. This, of course, would indicate the use of the wrong cable from the K2/100 to the computer. RS-232 voltages on anything but pins 2 and 3 of the DE9 connector are definitely bad news for the interface. >> The voltage on pin 8 (-5.87) is at the very low end of the >> expected -5 to -25v range shown on the schematic, and even the >> +30v on the HV bias supply is low at 19.54v --almost as though >> whatever is wrong in the chip is dragging >> down the -25v and and the rest of the HV bias. This is definitely low. What about the +90-150 supply? It appears that something is pulling the supply down. You should go through the diode voltage chart, comparing your measurements against those in the chart (page 61 of the KPA100 Rev C manual). I would not expect the MAX1406 to be dragging this down unless there is a short on a TX line coming out of the chip (or the chip is blown - a VERY rare event). Note that the 1406 does not need a -12V supply for the Rx side, so even without -12V, it should be passing the RxD through to the MCU. >> Resistance on the TXD/RXD leads at the chip is about 100 ohms to >> ground with the power removed. That seems a bit low by about a magnitude of order. In any case, the RxD input goes to an internal transistor base, while the output is a bipolar emitter/collector pair. they should not have the same low resistance to ground. >> All measurements made with a FLUKE 87 DMM. >> >> I don't know how but I'm afraid I've somehow crisped the MAX1406. >> Is there anything else I should try before replacing the chip??? Keep looking. Those diode measurements should be telling. If you don't find it by Monday, drop tech support an email. gary is always very good at helping solve problems like these. Good luck! -Jack Brindle, W6FB ======================================================================= _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Van W1WCG
On second look...
On Jun 25, 2005, at 1:06 PM, Frank Van Cleef W1WCG wrote: > After verifying continuity between the computer end of the RS232 > cable and the RF chokes on the KPA100 board (RFC6, RFC7) I meaured > voltages on the MAX1406 chip. Except for the 5 and 12v supply > voltages they were not what the chart in the manual described. The > pin voltages on the MAX1406/U4 chip were: > > 1 - +12.54 2 - -0.43 3 - > -0.03 4 - -0.43 > 5 - -0.44 6 - 0.44 7 - > -0.44 8 - -5.87 > 9 - 0.00 10 - 0.00 11- > 0.10 12 - -0.13 > 13 - -0.09 14 - 0.00 15- > -0.09 16 - 4.96 Pins 3, 5 and 7 of the MAX1406 are RS232 Tx Outputs. They should either be at a level above +3 volts, or below -3 volts. More specifically, the inputs for T1 and T3 are at ground, meaning that the outputs should be at the +12V rail. The measured voltages are NOT valid for a properly working circuit. I bet the chip is getting pretty hot, or has already disconnected itself (internally) from the pertinent supply. On another note, removing C38 should cause the amplifier to return to its normal operating voltages except for the RS-232 circuit. Now the question is that if indeed the MAX1406 is bad, how did it happen? -Jack Brindle, W6FB ======================================================================= _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Van W1WCG
You're right, Frank, I did misread P1 pin1 as coming from the AUXBUS.
However, the measurements I gave you for U4 Pin 12 is correct. On My board, it swings from 3.5V to 5V with communications under way and a steady 5V with the PC disconnected. Pin swings from 0 to -8V only if communications are underway, otherwise it sits at -10V. Pins 2, 3, 4, 7, 13 & 15 are all floating (unconnected) and Pin 6 should read whatever is coming from the PC. I noticed that Pin 6 is tied to the high voltage bias on the KIO2, but is left floating on the KPA100. On Sat, 25 Jun 2005 20:27:30 -0400, "Frank Van Cleef W1WCG" <[hidden email]> wrote: >Hi Matt, > >Thanks for your quick response! > >Looking at the schematic on page 62 of the KPA100 manual, in the lower >left-hand quadrant, I believe pin 12 of U4 is the input side of the TXD >inverter that drives the RS232 interface, and should be 0 or +5v depending >on the state of the RS232 serial signal going from the K2 to the interface. >The AUXBUS lead comes in on the pin of P1 on the opposite side of the >connector from the TX lead and goes to the MCU and pin 6 of J8 (the 9-pin >RS232 connector)through RFC 9, but does not actually connect to U4. I >believe the AUXBUS is OK because the KAT100 works just fine. I have not >looked at U4 pin 12 with a scope to see if it varies at all, but it is >slightly higher in voltage at 0.13v than the others, which suggests that >it's receiving a logic zero from the K2. The output on pin 5 (T2OUT) should >be near one of the RS232 supply voltages of either +12.54 or -5.87 (as >measured at pins 1 and 8) but instead there's only 0.44v. It's also very >strange that the voltages on pins 2, 4, 6 and 7 are all about the same, as >well as pin 3 which is an anomaly -- all these pins should be at one RS232 >level or the other. That's why I'm thinking the chip may be kaput. The >other really bad thing is that connecting the receive side from the computer >(which works fine with other devices such as a chip programmer) drags the >voltage on the receive line almost to zero -- this line is an input to the >MAX chip and the input should be high-impedance and not affect the voltage >on the line at all -- but it does. Gotta keep looking, I guess. > >Thanks again for your response, Matt, and I'll put a note on the reflector >when I do find out what happened. Any suggestions always welcomed!!! > >73, Van W1WCg > > >----- Original Message ----- >From: "Matt Osborn" <[hidden email]> >To: "Frank Van Cleef W1WCG" <[hidden email]> >Sent: Saturday, June 25, 2005 5:46 PM >Subject: Re: [Elecraft] RS232 problems with KPA100 > > >The high voltage bias supply on the KIO2 is between -6v to -12, so >your 19.4 is probably sufficient, but the KIO2 Vss, U4 pin 8 is -9v on >my KIO2. The MAX1406 wants from -13.2 to -10.8, but the absolute max >ratings are from +0.3 to -14.0, so you're probably OK with the -5.87. > >The real suspect is that U4 pin 12 should be reading +5V from the >AUXBUS on the control board. The only other use of AUXBUS on the >KPA100 is U1 pin 28 (RB7 Serial Programming Data). > >It would be worth checking out AUXBUX line for a short (C25) or an >open P1 pin 1. > >On Sat, 25 Jun 2005 16:06:46 -0400, "Frank Van Cleef W1WCG" ><[hidden email]> wrote: > >>Greetings, all you I/O experts out there -- I need some advice, please.... >> >>I'm using K2 #2634 with a KPA100 and KAT100; therefore the RS232 I/O is >>done by the MAX1406 chip on the KPA100. I've done computer control in the >>past but not for some months, so today I was rather surprised when I went >>to try out a new CAT program and could not get it to control or read out >>from the K2/KPA100. A breakout box showed no signal coming from the >>KPA100, and the TXD line from the computer indicated signals until I >>connected the KPA100; then the line seemed to be dragged down almost to 0v >>by the KPA100. >> >>After verifying continuity between the computer end of the RS232 cable and >>the RF chokes on the KPA100 board (RFC6, RFC7) I meaured voltages on the >>MAX1406 chip. Except for the 5 and 12v supply voltages they were not what >>the chart in the manual described. The pin voltages on the MAX1406/U4 chip >>were: >> >> 1 - +12.54 2 - -0.43 3 - -0.03 >> 4 - -0.43 >> 5 - -0.44 6 - 0.44 7 - -0.44 >> 8 - -5.87 >> 9 - 0.00 10 - 0.00 11- 0.10 >> 12 - -0.13 >> 13 - -0.09 14 - 0.00 15- -0.09 >> 16 - 4.96 >> >>The voltage on pin 8 (-5.87) is at the very low end of the expected -5 >>to -25v range shown on the schematic, and even the +30v on the HV bias >>supply is low at 19.54v --almost as though whatever is wrong in the chip is >>dragging >>down the -25v and and the rest of the HV bias. >> >>Resistance on the TXD/RXD leads at the chip is about 100 ohms to ground >>with the power removed. >>All measurements made with a FLUKE 87 DMM. >> >>I don't know how but I'm afraid I've somehow crisped the MAX1406. Is there >>anything else I should try before replacing the chip??? >> >>TIA, all >> >>Van, W1WCG >>_______________________________________________ >>Elecraft mailing list >>Post to: [hidden email] >>You must be a subscriber to post to the list. >>Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >>Help: http://mailman.qth.net/subscribers.htm >>Elecraft web page: http://www.elecraft.com > > > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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All,
I have a built Elecraft K2 tvtr for sale.... working tested and aligned on commercial test gear for NF. you can buy it for the kit price 360 USD, 200 UKP or 300 eu plus shipping will ship worldwide email me at gm4plm .a.t. hotmail.com thanks Simon _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I also meant to say it was for 2m!
doh! >From: "Simon Lewis" <[hidden email]> >To: [hidden email] >Subject: [Elecraft] 2m tvtr FS - built/tested >Date: Sun, 26 Jun 2005 19:18:57 +0000 > >All, > >I have a built Elecraft K2 tvtr for sale.... working tested and aligned on >commercial test gear for NF. > >you can buy it for the kit price 360 USD, 200 UKP or 300 eu plus shipping > >will ship worldwide > >email me at gm4plm .a.t. hotmail.com > >thanks > >Simon > > >_______________________________________________ >Elecraft mailing list >Post to: [hidden email] >You must be a subscriber to post to the list. >Subscriber Info (Addr. Change, sub, unsub etc.): >http://mailman.qth.net/mailman/listinfo/elecraft > >Help: http://mailman.qth.net/subscribers.htm >Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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