[K3] K3 driving KK1L band decoder
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[K3] K3 driving KK1L band decoder
 
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Is anyone else running a K3 with a KK1L band decoder? The K3 manual
states that "earlier K3s may require external pull-up resistors to 5 vdc." Did you need to do this? My KK1L board (built in 2006) seems to be loading down the K3 band outputs. Before I add the pull-up resistors, I just want to make sure that this isn't a sign of impending doom... Thanks and 73, --Ethan, K8GU/3. (K3 S/N 6714, TS-930S S/N 5010245) -- http://www.k8gu.com/ Repair. Re-use. Re-purpose. Recycle. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: [K3] K3 driving KK1L band decoder
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The PS2501-4 in the inputs of the KK1L band decoder are opto isolators. Pull up resistors will be required in the K3 in order to provide drive to the LEDs in the optos. > My KK1L board (built in 2006) seems to be loading down the K3 band > outputs. The K3 band data outputs are open drain - they can not be "loaded down" as they do not source voltage. Note: the KK1L design uses 3K3 Ohm series resistors to limit current to optos. Depending on the sensitivity (current transfer ratio) of the PS2501-4 you may need to reduce the resistance of those resistors in order obtain enough current through the LED. 73, ... Joe, W4TV On 9/6/2012 12:05 AM, Ethan Miller K8GU wrote: > Is anyone else running a K3 with a KK1L band decoder? The K3 manual > states that "earlier K3s may require external pull-up resistors to 5 > vdc." Did you need to do this? My KK1L board (built in 2006) seems > to be loading down the K3 band outputs. Before I add the pull-up > resistors, I just want to make sure that this isn't a sign of > impending doom... > > Thanks and 73, > > --Ethan, K8GU/3. (K3 S/N 6714, TS-930S S/N 5010245) > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: [K3] K3 driving KK1L band decoder
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As Joe mentioned you will need to do the pull up resistor update for
this to work. I run a splitter cable off the ACCY port on the K3 with one side going to my Quadra amp and the other side to the KK1L board. Due to the different impedences between the two it did not work (driving one by itself was fine...but not both). I had to add a buffer circuit between the ACCY output and the band decoder input. Once I did that the KK1L board worked great with the K3 connected to the Quadra at the same time. I don't recall what IC I used but it was easy to get...think I got it at radio shack. If you are only going to be connected to the band decoder you should not need the buffer. 73 Greg AB7R On 9/6/12, Joe Subich, W4TV <[hidden email]> wrote: > > The PS2501-4 in the inputs of the KK1L band decoder are opto isolators. > Pull up resistors will be required in the K3 in order to provide drive > to the LEDs in the optos. > >> My KK1L board (built in 2006) seems to be loading down the K3 band >> outputs. > > The K3 band data outputs are open drain - they can not be "loaded > down" as they do not source voltage. Note: the KK1L design uses > 3K3 Ohm series resistors to limit current to optos. Depending on > the sensitivity (current transfer ratio) of the PS2501-4 you may need > to reduce the resistance of those resistors in order obtain enough > current through the LED. > > 73, > > ... Joe, W4TV > > > On 9/6/2012 12:05 AM, Ethan Miller K8GU wrote: >> Is anyone else running a K3 with a KK1L band decoder? The K3 manual >> states that "earlier K3s may require external pull-up resistors to 5 >> vdc." Did you need to do this? My KK1L board (built in 2006) seems >> to be loading down the K3 band outputs. Before I add the pull-up >> resistors, I just want to make sure that this isn't a sign of >> impending doom... >> >> Thanks and 73, >> >> --Ethan, K8GU/3. (K3 S/N 6714, TS-930S S/N 5010245) >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: [K3] K3 driving KK1L band decoder
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> Due to the different impedences between the two it did not work > (driving one by itself was fine...but not both). I had to add a > buffer circuit between the ACCY output and the band decoder input. The Quadra has 1K series resistors and its inputs are clamped with diodes to +5V/Ground driving a CMOS buffer/line driver configured as a switch (input 1/input 2) . The KK1L decoder has 3.3K series resistors to the opto. In all probability the Quadra is "hogging" the available current from the band data outputs and the PS2501 optos are not getting enough drive. Replacing the 3K3 Ohm with 1K Ohm input resistors would probably have been preferable. Even without any loading by the Quadra, with the K3's 2K2 pull-up and 3K3 current limiting resistors LED current will be less than 1 mA which is marginal for a PS2501/4N32 type opto that has a typical current transfer ratio between 300 and 500% (current gain of only 3 to 5). 73, ... Joe, W4TV On 9/6/2012 11:07 AM, Greg wrote: > As Joe mentioned you will need to do the pull up resistor update for > this to work. > > I run a splitter cable off the ACCY port on the K3 with one side going > to my Quadra amp and the other side to the KK1L board. Due to the > different impedences between the two it did not work (driving one by > itself was fine...but not both). I had to add a buffer circuit > between the ACCY output and the band decoder input. Once I did that > the KK1L board worked great with the K3 connected to the Quadra at the > same time. I don't recall what IC I used but it was easy to > get...think I got it at radio shack. > If you are only going to be connected to the band decoder you should > not need the buffer. > > 73 > Greg > AB7R > > > On 9/6/12, Joe Subich, W4TV <[hidden email]> wrote: >> >> The PS2501-4 in the inputs of the KK1L band decoder are opto isolators. >> Pull up resistors will be required in the K3 in order to provide drive >> to the LEDs in the optos. >> >>> My KK1L board (built in 2006) seems to be loading down the K3 band >>> outputs. >> >> The K3 band data outputs are open drain - they can not be "loaded >> down" as they do not source voltage. Note: the KK1L design uses >> 3K3 Ohm series resistors to limit current to optos. Depending on >> the sensitivity (current transfer ratio) of the PS2501-4 you may need >> to reduce the resistance of those resistors in order obtain enough >> current through the LED. >> >> 73, >> >> ... Joe, W4TV >> >> >> On 9/6/2012 12:05 AM, Ethan Miller K8GU wrote: >>> Is anyone else running a K3 with a KK1L band decoder? The K3 manual >>> states that "earlier K3s may require external pull-up resistors to 5 >>> vdc." Did you need to do this? My KK1L board (built in 2006) seems >>> to be loading down the K3 band outputs. Before I add the pull-up >>> resistors, I just want to make sure that this isn't a sign of >>> impending doom... >>> >>> Thanks and 73, >>> >>> --Ethan, K8GU/3. (K3 S/N 6714, TS-930S S/N 5010245) >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> 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:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
Re: [K3] K3 driving KK1L band decoder
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As Joe suggested, I lowered the 3.3k resistors and now it works great.
Thanks for all the input! 73, --Ethan, K8GU/3. On Thu, Sep 6, 2012 at 4:07 PM, Joe Subich, W4TV <[hidden email]> wrote: > >> Due to the different impedences between the two it did not work >> (driving one by itself was fine...but not both). I had to add a >> buffer circuit between the ACCY output and the band decoder input. > > The Quadra has 1K series resistors and its inputs are clamped with > diodes to +5V/Ground driving a CMOS buffer/line driver configured > as a switch (input 1/input 2) . The KK1L decoder has 3.3K series > resistors to the opto. > > In all probability the Quadra is "hogging" the available current > from the band data outputs and the PS2501 optos are not getting > enough drive. Replacing the 3K3 Ohm with 1K Ohm input resistors > would probably have been preferable. Even without any loading by > the Quadra, with the K3's 2K2 pull-up and 3K3 current limiting > resistors LED current will be less than 1 mA which is marginal > for a PS2501/4N32 type opto that has a typical current transfer > ratio between 300 and 500% (current gain of only 3 to 5). > > 73, > > ... Joe, W4TV > > > On 9/6/2012 11:07 AM, Greg wrote: >> As Joe mentioned you will need to do the pull up resistor update for >> this to work. >> >> I run a splitter cable off the ACCY port on the K3 with one side going >> to my Quadra amp and the other side to the KK1L board. Due to the >> different impedences between the two it did not work (driving one by >> itself was fine...but not both). I had to add a buffer circuit >> between the ACCY output and the band decoder input. Once I did that >> the KK1L board worked great with the K3 connected to the Quadra at the >> same time. I don't recall what IC I used but it was easy to >> get...think I got it at radio shack. >> If you are only going to be connected to the band decoder you should >> not need the buffer. >> >> 73 >> Greg >> AB7R >> >> >> On 9/6/12, Joe Subich, W4TV <[hidden email]> wrote: >>> >>> The PS2501-4 in the inputs of the KK1L band decoder are opto isolators. >>> Pull up resistors will be required in the K3 in order to provide drive >>> to the LEDs in the optos. >>> >>>> My KK1L board (built in 2006) seems to be loading down the K3 band >>>> outputs. >>> >>> The K3 band data outputs are open drain - they can not be "loaded >>> down" as they do not source voltage. Note: the KK1L design uses >>> 3K3 Ohm series resistors to limit current to optos. Depending on >>> the sensitivity (current transfer ratio) of the PS2501-4 you may need >>> to reduce the resistance of those resistors in order obtain enough >>> current through the LED. >>> >>> 73, >>> >>> ... Joe, W4TV >>> >>> >>> On 9/6/2012 12:05 AM, Ethan Miller K8GU wrote: >>>> Is anyone else running a K3 with a KK1L band decoder? The K3 manual >>>> states that "earlier K3s may require external pull-up resistors to 5 >>>> vdc." Did you need to do this? My KK1L board (built in 2006) seems >>>> to be loading down the K3 band outputs. Before I add the pull-up >>>> resistors, I just want to make sure that this isn't a sign of >>>> impending doom... >>>> >>>> Thanks and 73, >>>> >>>> --Ethan, K8GU/3. (K3 S/N 6714, TS-930S S/N 5010245) >>>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[hidden email] >>> >>> 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:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html -- http://www.k8gu.com/ Repair. Re-use. Re-purpose. Recycle. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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