Re: [Elecraft] Using Elecraft KPA-1500 for 2 radios
N3RD (a fellow contester) is very responsive and knowledgeable on Top Ten products. You should contact him if you have any questions or concerns. I am bringing a Top Ten Decoder and 6 way switch to Bonaire for WPX SSB later this month. John KK9A - PJ4R Tom Georgens W2SC wrote: Hi Jim I bought a bunch of these for my station in 8P. When you reported your findings with these devices, I was very concerned. I had one in 8P with me at the time and I measured it in my AIM 4170. I could not reproduce your observations and used it on 10M with no obvious issues. Since I have been home, I took another set of measurements with my DG8SAQ VNA. They were essentially identical to what I measured in 8P. Just so we are clear on definitions, I measured them in in both directions using both ports and a precision 50 ohm load. In-A had a steadily rising SWR with frequency, maxing out at 1.1:1 on 28Mhz. In-B was slightly worse with the same shape and a max SWR of 1.15:1 at 28 Mhz. It was the same in both directions and did not change if the unused port was terminated or open. The isolation was essentially as advertised, over 80 dB up to 28 Mhz. Admittedly 1.15:1 is not world class, and could be better, but I don't consider it unacceptable and I plan on using the switches I bought. Are we drawing different conclusions from the same data? If you had different measurements, I would be curious if there was some design change along the way. I did not open them up. The units I have were bought from another ham, but they were unused. They also make a product called an Op Swapper that has some other functionality. What I am testing is the A/B station selector. 73, Tom W2SC __ 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] Using Elecraft KPA-1500 for 2 radios
I have been using 4 of these switches to share one amplifier between two K3s in an SO2R setup for the past 4 years. I was running two KPA500s in parallel, but recently switched to a KPA1500. No problems. I don’t operate 6 meters, and 10 meters hasn’t been open in so long I can honestly say I don’t operate there either! Ken K6MR From: elecraft-boun...@mailman.qth.net on behalf of Tom Georgens Sent: Monday, March 18, 2019 6:01:04 PM To: j...@audiosystemsgroup.com; elecraft@mailman.qth.net Subject: Re: [Elecraft] Using Elecraft KPA-1500 for 2 radios Thanks Jim I did not go all the way to 50Mhz. You comment indicated a knee at 21 Mhz, I did not see that. I saw a linear rise in SWR with frequency. At 28Mhx, the resistive component was still close to 50 ohms. It looks like a fixed inductance or capacitance that likely could be compensated away if I were so motivated. FWIW - their website only provides specifications up to 30 Mhz. It is possible that the design scope did not contemplate 50Mhz use. With 80db of relay isolation, termination should be moot. I was just verifying that it was. I saw no difference in a 50 ohm load or an open. In my use case, the unused port will be grounded (I think) so I wanted to be sure. They should be fine for my use case, but I can see why they did not work for you. I feel better knowing I was not missing anything in my measurements. Tom -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Jim Brown Sent: Monday, March 18, 2019 4:54 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Using Elecraft KPA-1500 for 2 radios On 3/18/2019 2:38 PM, Tom Georgens wrote: > Admittedly 1.15:1 is not world class, and could be better, but I don't consider it unacceptable and I plan on using the switches I bought. Are we drawing different conclusions from the same data? Hi Tom, Yes, we are. I was using a pair of them to switch inputs and outputs of a KPA500 an Ten Tec Titan. I use the KPA mostly on 6M, and what you saw on 10M was significantly worse there. Another important point. It is totally unrealistic to terminate un-used ports for isolation measurements, because un-used ports are often not matched at the frequency where isolation is of concern. I measure isolation between ports with a VNA (the DG8SAQ VNWA3e). In the case of this unit, I would measure between the two outputs. 73, Jim __ 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 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 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] Using Elecraft KPA-1500 for 2 radios
Thanks Jim I did not go all the way to 50Mhz. You comment indicated a knee at 21 Mhz, I did not see that. I saw a linear rise in SWR with frequency. At 28Mhx, the resistive component was still close to 50 ohms. It looks like a fixed inductance or capacitance that likely could be compensated away if I were so motivated. FWIW - their website only provides specifications up to 30 Mhz. It is possible that the design scope did not contemplate 50Mhz use. With 80db of relay isolation, termination should be moot. I was just verifying that it was. I saw no difference in a 50 ohm load or an open. In my use case, the unused port will be grounded (I think) so I wanted to be sure. They should be fine for my use case, but I can see why they did not work for you. I feel better knowing I was not missing anything in my measurements. Tom -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Jim Brown Sent: Monday, March 18, 2019 4:54 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Using Elecraft KPA-1500 for 2 radios On 3/18/2019 2:38 PM, Tom Georgens wrote: > Admittedly 1.15:1 is not world class, and could be better, but I don't consider it unacceptable and I plan on using the switches I bought. Are we drawing different conclusions from the same data? Hi Tom, Yes, we are. I was using a pair of them to switch inputs and outputs of a KPA500 an Ten Tec Titan. I use the KPA mostly on 6M, and what you saw on 10M was significantly worse there. Another important point. It is totally unrealistic to terminate un-used ports for isolation measurements, because un-used ports are often not matched at the frequency where isolation is of concern. I measure isolation between ports with a VNA (the DG8SAQ VNWA3e). In the case of this unit, I would measure between the two outputs. 73, Jim __ 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 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] Using Elecraft KPA-1500 for 2 radios
On 3/18/2019 2:38 PM, Tom Georgens wrote: Admittedly 1.15:1 is not world class, and could be better, but I don't consider it unacceptable and I plan on using the switches I bought. Are we drawing different conclusions from the same data? Hi Tom, Yes, we are. I was using a pair of them to switch inputs and outputs of a KPA500 an Ten Tec Titan. I use the KPA mostly on 6M, and what you saw on 10M was significantly worse there. Another important point. It is totally unrealistic to terminate un-used ports for isolation measurements, because un-used ports are often not matched at the frequency where isolation is of concern. I measure isolation between ports with a VNA (the DG8SAQ VNWA3e). In the case of this unit, I would measure between the two outputs. 73, Jim __ 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] Using Elecraft KPA-1500 for 2 radios
Hi Jim I bought a bunch of these for my station in 8P. When you reported your findings with these devices, I was very concerned. I had one in 8P with me at the time and I measured it in my AIM 4170. I could not reproduce your observations and used it on 10M with no obvious issues. Since I have been home, I took another set of measurements with my DG8SAQ VNA. They were essentially identical to what I measured in 8P. Just so we are clear on definitions, I measured them in in both directions using both ports and a precision 50 ohm load. In-A had a steadily rising SWR with frequency, maxing out at 1.1:1 on 28Mhz. In-B was slightly worse with the same shape and a max SWR of 1.15:1 at 28 Mhz. It was the same in both directions and did not change if the unused port was terminated or open. The isolation was essentially as advertised, over 80 dB up to 28 Mhz. Admittedly 1.15:1 is not world class, and could be better, but I don't consider it unacceptable and I plan on using the switches I bought. Are we drawing different conclusions from the same data? If you had different measurements, I would be curious if there was some design change along the way. I did not open them up. The units I have were bought from another ham, but they were unused. They also make a product called an Op Swapper that has some other functionality. What I am testing is the A/B station selector. 73, Tom W2SC -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Jim Brown Sent: Sunday, March 17, 2019 8:12 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] Using Elecraft KPA-1500 for 2 radios Not a great choice. SWR gets increasing nasty above 15M because the construction uses chassis as signal return rather than carrying it on the circuit board. It's a two-sided board, but the "ground" layer is broken under the traces that carry the RF, so return current can't flow on that layer. I didn't have the heart to try to measure crosstalk. 5-6 years ago, I bought several of them for antenna switching, and learned that the hard way. I modified them by paralleling copper braid from the connectors to the board and following the RF paths through the relays across the board as best I could. That reduced the SWR by about half. I've since replaced all of them, and they're for sale. :) 73, Jim K9YC On 3/17/2019 6:15 PM, Bill Steffey wrote: > i use topten a/b coax switches to switch between the kpa500 & > acom 2000 ... one in front of the amps , one in back also > have them switching between K3 & an Icom > > https://toptendevices.com/products/ab-station-selector/ __ 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 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] Using Elecraft KPA-1500 for 2 radios
Nope. The key inputs of both amps are buffered. Partial schematic of Titan is here. http://k9yc.com/TitanKeyingLogic.pdf K4XU once told me that it was his initials on the published schematics, and I think he later worked for Alpha. For operation with most rigs, the PTT position of the PTT/KEY switch is used for all modes. The QSK position is for a keying method used by early Ten Tec rigs where the operator keys the amp and the amp keys the rig. 73, Jim On 3/17/2019 5:56 PM, j...@kk9a.com wrote: So the different voltage sources from each amp do not bother each other when connected together with a Y or was only one amp turned on at a time? John KK9A Jim Brown K9YC wrote: Most of the rigs I've owned use a short on the key line to key the amp. If both of yours do that, you can probably connect them in parallel to the Key input of the power amp using an RCA Y-cable. I've done that for years to switch my K3 between my KPA500 and a 1500w tube amp (for many years a Ten Tec Titan, now an 87A). 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 __ 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] Using Elecraft KPA-1500 for 2 radios
Not a great choice. SWR gets increasing nasty above 15M because the construction uses chassis as signal return rather than carrying it on the circuit board. It's a two-sided board, but the "ground" layer is broken under the traces that carry the RF, so return current can't flow on that layer. I didn't have the heart to try to measure crosstalk. 5-6 years ago, I bought several of them for antenna switching, and learned that the hard way. I modified them by paralleling copper braid from the connectors to the board and following the RF paths through the relays across the board as best I could. That reduced the SWR by about half. I've since replaced all of them, and they're for sale. :) 73, Jim K9YC On 3/17/2019 6:15 PM, Bill Steffey wrote: i use topten a/b coax switches to switch between the kpa500 & acom 2000 ... one in front of the amps , one in back also have them switching between K3 & an Icom https://toptendevices.com/products/ab-station-selector/ __ 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] Using Elecraft KPA-1500 for 2 radios
i use topten a/b coax switches to switch between the kpa500 & acom 2000 ... one in front of the amps , one in back also have them switching between K3 & an Icom https://toptendevices.com/products/ab-station-selector/ On 3/17/2019 8:56 PM, j...@kk9a.com wrote: So the different voltage sources from each amp do not bother each other when connected together with a Y or was only one amp turned on at a time? John KK9A Jim Brown K9YC wrote: Most of the rigs I've owned use a short on the key line to key the amp. If both of yours do that, you can probably connect them in parallel to the Key input of the power amp using an RCA Y-cable. I've done that for years to switch my K3 between my KPA500 and a 1500w tube amp (for many years a Ten Tec Titan, now an 87A). 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 __ 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] Using Elecraft KPA-1500 for 2 radios
So the different voltage sources from each amp do not bother each other when connected together with a Y or was only one amp turned on at a time? John KK9A Jim Brown K9YC wrote: Most of the rigs I've owned use a short on the key line to key the amp. If both of yours do that, you can probably connect them in parallel to the Key input of the power amp using an RCA Y-cable. I've done that for years to switch my K3 between my KPA500 and a 1500w tube amp (for many years a Ten Tec Titan, now an 87A). 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
Re: [Elecraft] Using Elecraft KPA-1500 for 2 radios
I use a KR5L switch, but can no longer find on the internet. Possibly there is a circuit available that you could duplicate. I use mine to select rigs and a choice of Two amps, I only have one. 73, Bill K9YEQ https://wrj-tech.com/ -Original Message- From: elecraft-boun...@mailman.qth.net On Behalf Of Charlie Wirth Sent: Sunday, March 17, 2019 3:27 PM To: elecraft@mailman.qth.net Subject: [Elecraft] Using Elecraft KPA-1500 for 2 radios I own a Flex 6400 and an Icom 7700. I currently have the amplifier connected to the Flex. There may be times I want to use the Icom 7700. Other than disconnecting the send and control cables from the 1500 that go to the Flex and plugging in the same cables from the 7700 is there any other way to have both sets of cables connected to the amplifier safely? I would only be using one radio at a time and the other one would be turned off. I know that I would have to go into the menu settings of the amplifier to change the baud radio and radio when I use the other radio. Thanks, Charlie W3DDF __ 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 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] Using Elecraft KPA-1500 for 2 radios
I have a KPA/KAT500 combo connected to my Flex 6600 and K3. The K3 has all of the cables connected, so when it’s on, it controls the package with full integration. I use the “key interupter” to break out the key line. It’s “Y’d” with the key line from the Flex as Jim mentions into the KAT500. I switch input coaxes via a two port manual selector. That could be automated using one of several options if desired. Works great. tnx Mike / W5JR Alpharetta GA > On Mar 17, 2019, at 4:53 PM, Jim Brown wrote: > >> On 3/17/2019 1:26 PM, Charlie Wirth wrote: >> Other than disconnecting the send and control cables from the 1500 that go >> to the Flex and plugging in the same cables from the 7700 is there any other >> way to have both sets of cables connected to the amplifier safely? > > Several thoughts. First, both of Elecraft's power amps nearly instantaneously > detect the frequency of the drive signal, no there is no need for the rig to > send band information to the amp. Second, ALC should never be used to set TX > power -- that should always be done by setting the output power of the rig. > > The only necessary connections are the "amp key" line that puts the amp in > transmit mode and the coax between the rig and the amp input. Switching the > coax is easy with a SPDT coax switch or relay. > > Most of the rigs I've owned use a short on the key line to key the amp. If > both of yours do that, you can probably connect them in parallel to the Key > input of the power amp using an RCA Y-cable. I've done that for years to > switch my K3 between my KPA500 and a 1500w tube amp (for many years a Ten Tec > Titan, now an 87A). > > 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 __ 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] Using Elecraft KPA-1500 for 2 radios
On 3/17/2019 1:26 PM, Charlie Wirth wrote: Other than disconnecting the send and control cables from the 1500 that go to the Flex and plugging in the same cables from the 7700 is there any other way to have both sets of cables connected to the amplifier safely? Several thoughts. First, both of Elecraft's power amps nearly instantaneously detect the frequency of the drive signal, no there is no need for the rig to send band information to the amp. Second, ALC should never be used to set TX power -- that should always be done by setting the output power of the rig. The only necessary connections are the "amp key" line that puts the amp in transmit mode and the coax between the rig and the amp input. Switching the coax is easy with a SPDT coax switch or relay. Most of the rigs I've owned use a short on the key line to key the amp. If both of yours do that, you can probably connect them in parallel to the Key input of the power amp using an RCA Y-cable. I've done that for years to switch my K3 between my KPA500 and a 1500w tube amp (for many years a Ten Tec Titan, now an 87A). 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
[Elecraft] Using Elecraft KPA-1500 for 2 radios
I own a Flex 6400 and an Icom 7700. I currently have the amplifier connected to the Flex. There may be times I want to use the Icom 7700. Other than disconnecting the send and control cables from the 1500 that go to the Flex and plugging in the same cables from the 7700 is there any other way to have both sets of cables connected to the amplifier safely? I would only be using one radio at a time and the other one would be turned off. I know that I would have to go into the menu settings of the amplifier to change the baud radio and radio when I use the other radio. Thanks, Charlie W3DDF __ 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
