Re: [Elecraft] USB/3.5mm Extension?
Yes. At the point for the extension, the signals are RS-232, not USB. You should be able to use a much longer cable if need-be. Be sure to read through the manual - it should give you a much better feel for each connection. Enjoy the KAT500! 73, Jack, W6FB > On Nov 25, 2023, at 2:59 PM, W2HX wrote: > > Hi all, > > I have acquired my KAT500 and I am starting to play with it. I am trying to > use the KAT utility to control it which it does fine. Now I want to place it > between a transmitter and cable. Can I use a 10 foot 3.5mm TRS male to female > extension cable to extend the USB connector? My computer is farther away from > the antenna switching than the included cable can stretch. I think the REMOTE > capability might be in my future, but for now just trying a simple set up. > > > 73 Eugene W2HX > Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to jackbrin...@me.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
Andy, you do a great job of keeping me on my toes. But... Indeed, it is NOT true that the KAT500 uses TTL signal levels for the serial port. The KAT500 has voltage translation circuitry that allows for the use of quasi-RS232 signal levels. Quasi? Yes, the transmit data goes to +12 Volts, but it only goes down to chassis ground levels. This actually gets the RS-232 specification which has a transition band in the 1-2 volt range. The receive circuitry is fully capable of translating RS-232 signal levels to the +5, ground levels used internally to the KAT500. Note that the KAT500 can receive TTL-level signals, but it does not drive them. What this means is that if you were to drive TTL chips directly from the KAT500’s data port you would probably have to replace a lot of those chips until you realize they cannot withstand the +12V on their inputs. So yes, the extension cable may be used. Just don’t use a high-capacitance cable (which usually means a very long one), as the KAT may not be able to drive the load on the far end. 73, Jack, W6FB > On Nov 28, 2023, at 8:46 AM, Andy Durbin wrote: > > "Yes. At the point for the extension, the signals are RS-232, not USB. You > should be able to use a much longer cable if need-be." > > Isn't it true that the KAT500 USB cable uses RS-232 protocol but TTL signal > levels? TTL may not be as tolerant of length extension as true RS-232. > Certainly no problem with about 10 ft extension though as my KAT500 > USB/Serial extension is close to that long when my KAT500 is connected to the > PC . > > The KAT500 PC interface is a bit unusual as it seems to be designed to use > TLL but also accepts true RS-232 levels with no problem. A true RS-232 > receiver may not operate with a single ended TTL input. RS-232 signals swing > positive and negative and are only zero volts when the driver is not powered. > TTL swings between 0 V and 5 V. RS-232 compliant transmitters are also > required to tolerate continuous short circuit without damage. > > Elecraft was careful not to describe the KAT500 PC port, or the USB cable, as > RS-232. > > These details will only be of interest to anyone considering making a device > that interfaces directly with KAT500. > > 73, > Andy, k3wyc > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to jackbrin...@me.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
"Indeed, it is NOT true that the KAT500 uses TTL signal levels for the serial port. " Ah, but I said "Isn't it true that the KAT500 USB cable uses RS-232 protocol but TTL signal levels? " Perhaps I should have been more specific. My recollection is that the USB/Serial cable transmits a TTL signal. I have no way to know the receiver characteristics of that interface dongle. I did study the KAT500 I/O schematic to understand that end of the connection. Anyway, not posting to "keep you on your toes". I was confused by this interface when I first decided to work with it so didn't want people to assume it was RS-232 compliant. 73, Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
So that everyone reading understands, the KAT500 IS RS-232/IEEE-232 compatible in its voltage levels. It is NOT TTL (0,5v) compatible. 73, Jack, W6FB Sent from my iPhone > On Nov 28, 2023, at 10:14 AM, Andy Durbin wrote: > > > "Indeed, it is NOT true that the KAT500 uses TTL signal levels for the serial > port. " > > Ah, but I said "Isn't it true that the KAT500 USB cable uses RS-232 protocol > but TTL signal levels? " Perhaps I should have been more specific. My > recollection is that the USB/Serial cable transmits a TTL signal. I have no > way to know the receiver characteristics of that interface dongle. I did > study the KAT500 I/O schematic to understand that end of the connection. > > Anyway, not posting to "keep you on your toes". I was confused by this > interface when I first decided to work with it so didn't want people to > assume it was RS-232 compliant. > > 73, > Andy, k3wyc > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
Well to be pedantic the RS-232 (EIA-232) spec says the following: " Valid signals are either in the range of +3 to +15 volts or the range −3 to −15 volts with respect to the "Common Ground" (GND) pin; consequently, the range between −3 and +3 volts is not a valid RS-232 level." So the spacing signal should not be ground if you want to adhere strictly to the standard. Having said that, I'm sure it all works very well! 73 Eugene W2HX Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Jack Brindle via Elecraft Sent: Tuesday, November 28, 2023 11:48 AM To: Andy Durbin Cc: Elecraft@mailman.qth.net Subject: Re: [Elecraft] USB/3.5mm Extension? So that everyone reading understands, the KAT500 IS RS-232/IEEE-232 compatible in its voltage levels. It is NOT TTL (0,5v) compatible. 73, Jack, W6FB Sent from my iPhone > On Nov 28, 2023, at 10:14 AM, Andy Durbin wrote: > > > "Indeed, it is NOT true that the KAT500 uses TTL signal levels for the serial > port. " > > Ah, but I said "Isn't it true that the KAT500 USB cable uses RS-232 protocol > but TTL signal levels? " Perhaps I should have been more specific. My > recollection is that the USB/Serial cable transmits a TTL signal. I have no > way to know the receiver characteristics of that interface dongle. I did > study the KAT500 I/O schematic to understand that end of the connection. > > Anyway, not posting to "keep you on your toes". I was confused by this > interface when I first decided to work with it so didn't want people to > assume it was RS-232 compliant. > > 73, > Andy, k3wyc > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to w...@w2hx.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
Scope traces for a typical KAT500 serial data interface can be found here - https://www.dropbox.com/scl/fi/ypk0ks16rl03d55ugm4t9/KAT500-signal-levels.pdf?rlkey=7iahis4xp0jnua3c8s577cxjq&dl=0 I can also confirm that KAT500 works just fine when interfaced with a genuine MAX 3232 RS-232 line driver. 73, Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
On 11/28/2023 6:46 AM, Andy Durbin wrote: Isn't it true that the KAT500 USB cable uses RS-232 protocol but TTL signal levels? T RS-232 is NOT a matched transmission line -- it's a low-Z source and high-Z input. The limitation on line length is not signal strength, but rounding of the pulses by cable capacitance. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
Andy’s point that the KXUSB actually has 0 to 5V output on its TxD line is correct. This is most likely the limiter in how long of a cable you can have between the KXUSB and the KAT500. The actual length is probably best derived by trial and error. As K9YC points out, the rise and fall times of the signals will be the limiting factor, and will actually determine the maximum length. The rise and fall times need to be pretty short due to the data rate used by the KAT500 (38400 bps). As an educated guess, I would suspect that an extension of 5 or maybe even 10 feet should work, depending on the cable capacitance. If you see any strangeness to the communications, use a shorter cable. One other thing - Andy is a good friend, someone with whom I enjoy having deep technical discussions. We learn a lot from each other, and he contributes quite a bit to the technical nature of the list. His presence here is very much welcome. 73, Jack, W6FB > On Nov 28, 2023, at 10:14 AM, Andy Durbin wrote: > > "Indeed, it is NOT true that the KAT500 uses TTL signal levels for the serial > port. " > > Ah, but I said "Isn't it true that the KAT500 USB cable uses RS-232 protocol > but TTL signal levels? " Perhaps I should have been more specific. My > recollection is that the USB/Serial cable transmits a TTL signal. I have no > way to know the receiver characteristics of that interface dongle. I did > study the KAT500 I/O schematic to understand that end of the connection. > > Anyway, not posting to "keep you on your toes". I was confused by this > interface when I first decided to work with it so didn't want people to > assume it was RS-232 compliant. > > 73, > Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
"Scope traces for a typical KAT500 serial data interface can be found here - https://www.dropbox.com/scl/fi/ypk0ks16rl03d55ugm4t9/KAT500-signal-levels.pdf?rlkey=7iahis4xp0jnua3c8s577cxjq&dl=0"; The depicted voltage levels for KAT500 driving the KXUSB were not typical. In my station the KAT500 serial port transmitter connects to both the KXUSB receiver and a MAX3232. The MAX3232 terminates the input with 5k which is almost identical to the KAT500 transmitter source impedance. The observed voltage is higher when this 5k load is not present. Thanks to Jack, W6FB, for spotting this error. 73, Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] USB/3.5mm Extension?
On 11/29/2023 7:47 AM, Andy Durbin wrote: The MAX3232 terminates the input with 5k which is almost identical to the KAT500 transmitter source impedance. The impedance that must be matched to preserve waveshape is that of the transmission line. The RS232 protocol does not do that. Most other protocols do. Zo of practical cables is in the range of 50-100 ohms. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
