Re: [Elecraft] Interesting observations after installing antenna switch
Ken; I just did an analysis of the circuit you described using the RAAS-4A schematic from the WA4MCM web site, and my local docs for both the K3S and KPA500. This is rather interesting, but with the antenna selector in the circuit, the band voltage will never go above about 0.6 volts. Thus, if you use the BCD or K3 settings on the KPA500, it will always think it is on 60 meters. That isn’t completely true. As K9YC states, the KPA500 always does a frequency count of the input signal, and will change to that band, ignoring the BAND inputs, if it is different. Thus you have been transmitting on the correct bands, but the band inputs have pretty much been ignored. The analysis: The K3S band outputs use a 2.2K resistor in series with a BAT-54 schottky diode to the +5V rail. The diode will drop just a few tenths of a volt. The band lines have a 220 ohm resistor in series for RFI protection. This needs to be considered whenever an external device has a pull-up or pulldown resistor, as the RAAS-4A does. All this is driven by a TPIC6C595 I/O chip, which has open-drain outputs. Thus it switches between ground and float. When floating, the pull-up is the main source of 5V for the band lines. For the record, the 2.2K pull-up resistor is not in play when the TPIC drives the BAND line to ground, but the 220 series resistor is still in play. The KPA-500’s inputs are a bit more simple since they do not drive the BAND lines. The input goes through a 100 uH RF choke, to the cathode of a BAT-54 diode. The anode is connected to the microcontroller input with a 10K pull-up applied to +5V. This does a very good job of isolating the micro from the band lines - it either sees a ground or the +5V pull-up. This really means that the “ground” (low input) MUST go below the microcontroller’s input threshold for it to be recognized at being low. The voltage drop of the diode (somewhere around 0.3 volts or so) must also be considered. The RAAS-4A itself has circuitry that modifies the band levels. It has a 1K series resistor to a 3V zener diode in parallel with a 10K resistor to ground. This protects the base of a 2N3904 transistor from extraneous voltage excursions. The diode clamps the input voltage at 3 volts. When the K3S indicates the band voltage is high, we have a circuit thus: +5V - 2.2K - 220 - 1K - +3V. The voltage at the junction of the 220 and 1K resistors will go no higher than about 0.6 ohms. The KPA500 and other devices are listening at this junction, and will never see a BAND input go high. (The threshold is about 2 volts per spec). The correction would be to eliminate any low-value resistance that will modify the K3S’s BAND levels. A series diode with pull-up on its anode does this quite nicely. You might also consider driving the band outputs with a non-inverting quad driver, with the outputs going to the band switch. And be sure to add significant RFI protection (0.01 cap to ground, 100 uH RF choke, etc). By the way, when BAND is low, the line will actually be about 0.1V. That is from the KPA500 providing a 10K pull-up to +5V, through a schottky diode drop to the 220 ohm resistor in the K3S to ground. That 220 ohm resistor really does have an effect on the band lines when third-party devices come into play! This isn’t the first time we have come across this problem with external equipment in the system, and won’t be the last. I just hope that in the future, designers will give a lot more thought to how they do things (and why). I think the question here isn’t how WA4MCM should fix his design (he should), but how Ken will get his device to work the way he wants it to work. 73, Jack, W6FB > On Aug 29, 2023, at 2:25 PM, ken.k...@gmail.com wrote: > > Hi Ray. Either I was unclear in my description, or it was mis-read. > According to the display of the amplifier, it is ALWAYS set for the 60 meter > band, regardless of what band I am actually operating. > > > > 73, > > Ken, KJ9B > > > > From: Ray > Sent: Tuesday, August 29, 2023 3:06 PM > To: ken.k...@gmail.com; Elecraft@mailman.qth.net > Subject: RE: [Elecraft] Interesting observations after installing antenna > switch > > > > The 60 meter band is 100 Watts ERP Legal Limit ! > > The RAAS4a is Trying to keep you out of Trouble… > > > > Ray WA6VAB K3 > > > > > > From: ken.k...@gmail.com <mailto:ken.k...@gmail.com> > Sent: Tuesday, August 29, 2023 11:58 AM > To: Elecraft@mailman.qth.net <mailto:Elecraft@mailman.qth.net> > Subject: [Elecraft] Interesting observations after installing antenna switch > > > > Hi all. I recently put a remote antenna switch in my HF system. This > > switch (a WA4MCM kit, RAAS-4a) is capable of reading band data from several > > radios, including my Elecraft K3S. For several years I have had a KPA-500 > > ampli
Re: [Elecraft] Interesting observations after installing antenna switch
On 8/29/2023 11:58 AM, ken.k...@gmail.com wrote: The designer of the switch says that each band data channel only draws around 4 mA, with each channel buffered by a transistor switch in an attempt to isolate the band data voltage from the radio. In my working days in the entertainment industry, I would use a distribution amp to give me multiple audio outputs when needed. Is there such a "distribution amp" available for the band data signals? Would the Elecraft KRC2 accomplish this? There are multiple formats for band data. I suspect that the one used by your switch is one that is not compatible with Elecraft's. It's been a while since I worked with the KRC2 that's in W6GJB's contesting trailer, but I think I remember that it can be set for all of the common band data formats. I suggest studying the manual for the KRC2 -- most if not all Elecraft manuals are on their website. Your KPA500 is probably throwing an alarm because it's not being band-switched. However -- I've never sent band data to my Elecraft amps or tuners -- all it takes is a single dit or tap on the mic for them to detect frequency and switch on their own. I don't see mention of a tuner, so I suspect all of your antennas are reasonably matched to coax. If not, remember that any transmission line transforms any mismatched load to some different complex impedance (that is, resistance and reactance), depending on its length. So if line lengths changed as a result of the switch, it could change that impedance, and some impedances with the same VSWR look different to the transmitter than others. 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] Interesting observations after installing antenna switch
Download (or look at) the schematic for the switch/controller. It has 3.3V zener diodes across each of the BCD inputs. The K3/K3S has pull-up resistors to *5 V* on each of the BCD outputs. The switch is not allowing the inputs to the KPA500 to reach the 5V necessary to resister as "High" thus the input is always (or 60 Meters). I suggest you contact the designer/manufacturer of your switch and ask him what hi will do to fix his defective product (since he claims compatibility with Elecraft). 73, ... Joe, W4TV On 8/29/2023 3:37 PM, W3FPR wrote: Ken, Check the voltage/current ratings on the band data lines for both the amp and your antenna switch. It sounds like they may not be compatible. 60 meters is encoded as "", so if the voltage is not high enough (perhaps due to insufficient current), it will show 60 meters. 73, Don W3FPR On 8/29/2023 3:25 PM, ken.k...@gmail.com wrote: Hi Ray. Either I was unclear in my description, or it was mis-read. According to the display of the amplifier, it is ALWAYS set for the 60 meter band, regardless of what band I am actually operating. __ 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] Interesting observations after installing antenna switch
Ken, Check the voltage/current ratings on the band data lines for both the amp and your antenna switch. It sounds like they may not be compatible. 60 meters is encoded as "", so if the voltage is not high enough (perhaps due to insufficient current), it will show 60 meters. 73, Don W3FPR On 8/29/2023 3:25 PM, ken.k...@gmail.com wrote: Hi Ray. Either I was unclear in my description, or it was mis-read. According to the display of the amplifier, it is ALWAYS set for the 60 meter band, regardless of what band I am actually operating. __ 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] Interesting observations after installing antenna switch
Hi Ray. Either I was unclear in my description, or it was mis-read. According to the display of the amplifier, it is ALWAYS set for the 60 meter band, regardless of what band I am actually operating. 73, Ken, KJ9B From: Ray Sent: Tuesday, August 29, 2023 3:06 PM To: ken.k...@gmail.com; Elecraft@mailman.qth.net Subject: RE: [Elecraft] Interesting observations after installing antenna switch The 60 meter band is 100 Watts ERP Legal Limit ! The RAAS4a is Trying to keep you out of Trouble… Ray WA6VAB K3 From: ken.k...@gmail.com <mailto:ken.k...@gmail.com> Sent: Tuesday, August 29, 2023 11:58 AM To: Elecraft@mailman.qth.net <mailto:Elecraft@mailman.qth.net> Subject: [Elecraft] Interesting observations after installing antenna switch Hi all. I recently put a remote antenna switch in my HF system. This switch (a WA4MCM kit, RAAS-4a) is capable of reading band data from several radios, including my Elecraft K3S. For several years I have had a KPA-500 amplifier in line, working seamlessly with my K3S, band switching automatically, etc. In order to get band data for the new switch, I installed the "Y" cable that came with the KPAK3AUX Cable set that I purchased with the amp. After installing the new switch, everything works fine, with a couple of small "quirky" things. For the past year or so, I have had my amp set to automatically go into stand-by when I switch bands. After installing the new switch, I noticed that when changing bands, the amp no longer automatically goes to stand-by. Furthermore, after making a band change and transmitting for the first time on the new band (with the amp in "operate" mode), the amp will drop out of "operate" shortly after keying up. No error message or error beep happens, it just drops out. After manually putting the amp back in "operate" mode, everything was fine. After I noticed that, I just disabled the automatic switch to stand-by feature of the KPA-500, and that took care of that. Another interesting, and possibly more significant, anomaly I noticed after installing the new switch is according to the display on the amplifier, the amplifier is always on the 60 meter band, displaying "5.3 MHZ". I normally only display the temperature of the amplifier, but my son noticed this when he was operating from my station and changed the display. When he noticed this, we were operating a special event station and had operated on most bands other than 60 meters for quite some time with the amp apparently set for 60 meters, with no obvious ill effects. The designer of the switch says that each band data channel only draws around 4 mA, with each channel buffered by a transistor switch in an attempt to isolate the band data voltage from the radio. In my working days in the entertainment industry, I would use a distribution amp to give me multiple audio outputs when needed. Is there such a "distribution amp" available for the band data signals? Would the Elecraft KRC2 accomplish this? I appreciate any input offered on my situation. 73, Ken, KJ9B __ 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 wa6...@gmail.com <mailto:wa6...@gmail.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] Interesting observations after installing antenna switch
There are links at the bottom of EVERY message leading to the QTH Mailman page, where you can enter you email address and click 'unsubscribe'. On 2023-08-29 15:08, Steven Ayers wrote: How do you unsubscribe __ 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 n8...@densbe.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] Interesting observations after installing antenna switch
How do you unsubscribe On Tue, Aug 29, 2023, 13:59 wrote: > Hi all. I recently put a remote antenna switch in my HF system. This > switch (a WA4MCM kit, RAAS-4a) is capable of reading band data from several > radios, including my Elecraft K3S. For several years I have had a KPA-500 > amplifier in line, working seamlessly with my K3S, band switching > automatically, etc. In order to get band data for the new switch, I > installed the "Y" cable that came with the KPAK3AUX Cable set that I > purchased with the amp. After installing the new switch, everything works > fine, with a couple of small "quirky" things. For the past year or so, I > have had my amp set to automatically go into stand-by when I switch bands. > After installing the new switch, I noticed that when changing bands, the > amp > no longer automatically goes to stand-by. Furthermore, after making a band > change and transmitting for the first time on the new band (with the amp in > "operate" mode), the amp will drop out of "operate" shortly after keying > up. > No error message or error beep happens, it just drops out. After manually > putting the amp back in "operate" mode, everything was fine. After I > noticed that, I just disabled the automatic switch to stand-by feature of > the KPA-500, and that took care of that. Another interesting, and possibly > more significant, anomaly I noticed after installing the new switch is > according to the display on the amplifier, the amplifier is always on the > 60 > meter band, displaying "5.3 MHZ". I normally only display the temperature > of the amplifier, but my son noticed this when he was operating from my > station and changed the display. When he noticed this, we were operating a > special event station and had operated on most bands other than 60 meters > for quite some time with the amp apparently set for 60 meters, with no > obvious ill effects. > > > > The designer of the switch says that each band data channel only draws > around 4 mA, with each channel buffered by a transistor switch in an > attempt > to isolate the band data voltage from the radio. In my working days in the > entertainment industry, I would use a distribution amp to give me multiple > audio outputs when needed. Is there such a "distribution amp" available > for > the band data signals? Would the Elecraft KRC2 accomplish this? > > > > I appreciate any input offered on my situation. > > > > 73, > > Ken, KJ9B > > __ > 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 emtstevenay...@gmail.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] Interesting observations after installing antenna switch
__ 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
[Elecraft] Interesting observations after installing antenna switch
Hi all. I recently put a remote antenna switch in my HF system. This switch (a WA4MCM kit, RAAS-4a) is capable of reading band data from several radios, including my Elecraft K3S. For several years I have had a KPA-500 amplifier in line, working seamlessly with my K3S, band switching automatically, etc. In order to get band data for the new switch, I installed the "Y" cable that came with the KPAK3AUX Cable set that I purchased with the amp. After installing the new switch, everything works fine, with a couple of small "quirky" things. For the past year or so, I have had my amp set to automatically go into stand-by when I switch bands. After installing the new switch, I noticed that when changing bands, the amp no longer automatically goes to stand-by. Furthermore, after making a band change and transmitting for the first time on the new band (with the amp in "operate" mode), the amp will drop out of "operate" shortly after keying up. No error message or error beep happens, it just drops out. After manually putting the amp back in "operate" mode, everything was fine. After I noticed that, I just disabled the automatic switch to stand-by feature of the KPA-500, and that took care of that. Another interesting, and possibly more significant, anomaly I noticed after installing the new switch is according to the display on the amplifier, the amplifier is always on the 60 meter band, displaying "5.3 MHZ". I normally only display the temperature of the amplifier, but my son noticed this when he was operating from my station and changed the display. When he noticed this, we were operating a special event station and had operated on most bands other than 60 meters for quite some time with the amp apparently set for 60 meters, with no obvious ill effects. The designer of the switch says that each band data channel only draws around 4 mA, with each channel buffered by a transistor switch in an attempt to isolate the band data voltage from the radio. In my working days in the entertainment industry, I would use a distribution amp to give me multiple audio outputs when needed. Is there such a "distribution amp" available for the band data signals? Would the Elecraft KRC2 accomplish this? I appreciate any input offered on my situation. 73, Ken, KJ9B __ 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
