Re: [Elecraft] KX3 Operating Tip: Determining the ATU's L/C values and L-net configuration
Wayne wrote: You can't get L-network information via the menu. But you can send an AK; (ATU relay settings) command from the KX3 Utility Command Tester. The response format is AKaabbcc;, where: aa = inductance bitmap in ASCII hex format bb = capacitance bitmap in ASCII hex format cc = misc relays bitmap in ASCII hex format At present only bit 0 of byte cc is defined: 00 = capacitance on antenna side 01 = capacitance on transmitter side Example: Suppose you get back AK031A01;. First convert the hex quantities to binary: 03 = 0011 (L) 1A = 00011010 (C) 01 = 0001 (network selection) Now compare these values to the KXAT3 schematic. 0011 for L means that two smallest inductors are switched in. Add these together to determine the total L value. Similarly, add up the selected capacitors based on the binary value 00011010. Finally, you can determine the network configuration from the value 0001. In this case, the capacitance is on the transmitter side of the series inductance. There is a quick way to convert the AKaabbcc word to actual L and C values and configuration that does not require looking at a binary bit pattern, correlating each set bit to a specific relay and reactance on a schematic, and then adding up the connected values. The KXAT3 has a maximum ATU inductance L = 15.93 uH. The eight ATU inductance switching relays divide this into 256 (almost) identical steps. When the ATU has found its best match, a hexadecimal value is set in aa that is the number of those steps used by the current ATU inductance setting. So: 1L. The inductance step size is 15.93 uH / 256 = 0.0622 uH. 2L. Convert the hexadecimal value aa to the decimal value AAA. 3L. Total inductance connected is AAA x 0.0622 uH. The KXAT3 has a maximum ATU capacitance C = 2683 pF. The eight ATU capacitance switching relays divide this into 256 (almost) identical steps. When the ATU has found its best match, a hexadecimal value is set in bb that is the number of those steps used by the current ATU capacitance setting. So: 1C. The capacitance step size is 2683 pF / 256 = 10.48 pF. 2C. Convert the hexadecimal value bb to the decimal value BBB. 3C. Total capacitance connected is BBB x 10.48 pF. That's all it takes to compute the effective L and C values. The only iffy part for a few may be converting a hexadecimal value to its decimal equivalent. Once the L and C values are known, all that remains is to determine if the capacitor is connected on the antenna side (cc = 00) or the transmitter side (cc = 01). For Wayne's example of AK031A01: The ATU inductance byte is 03(hex) = 003(decimal). The ATU inductance thus is 3 x 0.0622 uH = 0.1866 uH. The ATU capacitance byte is 1A(hex) = 025(decimal). The ATU capacitance thus is 25 x 10.48 pF = 262 pF. The ATU capacitance connection byte is 01(hex). The ATU capacitor is thus on the transmitter side. So, the ATU reactance is a series inductance of 0.1866 pF with a capacitance of 262 pf from the transmitter end of the inductance to common. NOTE: Because the eight inductances or capacitances are not always *exact* factors of 2 from each other due to practical individual manufacturing or value availability issues, there will sometimes be very slight differences between the results from this quick approach, and that from determining which bits are set in two bytes and applying that to relay configuration with associated reactance values in the ATU. Applying that painstaking approach to Wayne's example yields an inductance value of 0.18 uH (vs. 0.1866 uH) and a capacitance value of 264 pF (vs. 262 pF). Pretty darn close! Were one very often interested in this detail about KXAT3 settings, it would be great if firmware did the required work. If the ATU is not installed, or if the ATU MD menu entry parameter is set to one of the L/C test values, AK00; is returned. If the ATU is in bypass mode, quasi-bypass values are shown. (These were selected to approximately cancel out the ATU's own stray reactance on each band.) In AUTO mode, the working auto-tuned values are shown. I admire the attention to small detail that the description of the bypass function shows. 73, Mike / KK5F __ 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
Re: [Elecraft] KX3 Operating Tip: Determining the ATU's L/C values and L-net configuration
Mike Morrow wrote: That's all it takes to compute the effective L and C values. Good idea. I should also have pointed out that knowing the L and C values used doesn't necessarily tell you what your antenna impedance is. On higher bands, in particular, all ATUs have strays that make them look like a higher-order network than just an L-net (e.g., it can be modeled as a pi-net in some cases). We've done some modeling of the KAT500, which is similar, to aid in tracking the antenna impedance. It's a very complex set of calculations. The only iffy part for a few may be converting a hexadecimal value to its decimal equivalent. Many scientific calculators will do this. You can also find hex- decimal calculators on the web. 73, Wayne N6KR __ 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
[Elecraft] KX3 Operating Tip: Determining the ATU's L/C values and L-net configuration
Heinz (OE5EEP) wrote: The KXAT3 internal ATU works really great! I can match a dipole of 2x 6.8m with 7m of double-wire feedline erected as inverted V on all bands from 40 to 6m I wonder if there is a way to retrieve the L/C combinations and values used to achieve a match. Is this somewhere hidden in the menu? You can't get L-network information via the menu. But you can send an AK; (ATU relay settings) command from the KX3 Utility Command Tester. This command is intended for use during automated factory test but may be of interest to operators as well. The response format is “AKaabbcc;”, where: aa = inductance bitmap in ASCII hex format bb = capacitance bitmap in ASCII hex format cc = misc relays bitmap in ASCII hex format At present only bit 0 of byte cc is defined: 00 = capacitance on antenna side 01 = capacitance on transmitter side Example: Suppose you get back AK031A01;. First convert the hex quantities to binary: 03 = 0011 (L) 1A = 00011010 (C) 01 = 0001 (network selection) Now compare these values to the KXAT3 schematic. 0011 for L means that two smallest inductors are switched in. Add these together to determine the total L value. Similarly, add up the selected capacitors based on the binary value 00011010. Finally, you can determine the network configuration from the value 0001. In this case, the capacitance is on the transmitter side of the series inductance. If the ATU is not installed, or if the ATU MD menu entry parameter is set to one of the L/C test values, “AK00;” is returned. If the ATU is in “bypass” mode, quasi-bypass values are shown. (These were selected to approximately cancel out the ATU's own stray reactance on each band.) In AUTO mode, the working auto-tuned values are shown. Wayne __ 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
Re: [Elecraft] KX3 Operating Tip: Determining the ATU's L/C values and L-net configuration
Wayne == Wayne Burdick n...@elecraft.com writes: Wayne You can't get L-network information via the menu. But you can send an Wayne AK; (ATU relay settings) command from the KX3 Utility Command Wayne Tester. This command is intended for use during automated Wayne factory test Wayne but may be of interest to operators as well. Will you please make this available on the K3 as well, at some point? Pf -- Pierfrancesco Caci, ik5pvx __ 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
Re: [Elecraft] KX3 Operating Tip: Determining the ATU's L/C values and L-net configuration
Noted for a future release. Thanks, Wayne N6KR On Aug 2, 2012, at 11:39 AM, Pierfrancesco Caci wrote: Wayne == Wayne Burdick n...@elecraft.com writes: Wayne You can't get L-network information via the menu. But you can send an Wayne AK; (ATU relay settings) command from the KX3 Utility Command Wayne Tester. This command is intended for use during automated Wayne factory test Wayne but may be of interest to operators as well. Will you please make this available on the K3 as well, at some point? Pf -- Pierfrancesco Caci, ik5pvx __ 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
