Jim, > The problem comes when I add the KPA500. The RCS12 continues to read > and follow the band changes from the K3 but the KPA500 switches to 5.3 > (60m) and stays there regardless of K3 front panel switches.The KPA500 > also operates properly when the cable is connected to the Y connector > but not the RCS12. So the cable is not at fault.
It is likely that the RCS-12 is loading the band data lines preventing the KPA-500 from seeing the data from the K3. This has been reported before ... you may want to look in the archives for a solution: http://mailman.qth.net/pipermail/elecraft/ I do not remember if the solution is as simple as blocking diodes in each line or if the RCS-12 requires a high impedance line driver for isolation. 73, ... Joe, W4TV On 11/23/2012 9:39 AM, Jim Miller wrote:
I've recently added an MFJ RCS12 controller to my K3/KPA3 setup and I'm having some problems. I've built and checked the BANDDATA cable and it only has the four BCD lines plus ground. I'm using the Elecraft Y-cable and Keyline interrupter. (The KEYOUT signal is connected to the KPA500 via the supplied RCA cable directly. This will change of course as the RCS12 becomes operational and again when the KAT500 is added...) The RCS12 reads the BANDDATA <0-3> lines and switches the relay outputs as expected. The problem comes when I add the KPA500. The RCS12 continues to read and follow the band changes from the K3 but the KPA500 switches to 5.3 (60m) and stays there regardless of K3 front panel switches.The KPA500 also operates properly when the cable is connected to the Y connector but not the RCS12. So the cable is not at fault. The K3 and RCS12 respond properly to the front panel band selection switching of the KPA500 but the KPA500 doesn't change from the 60M indication. It seems that the KPA500 is reading zeros on the K3 band data outputs yet capable of sending via AUXBUS band data change requests to the K3 which is then transmitted via the BANDDATA <0-3> lines to the RCS12 yet the KPA500 remains stuck at 60M. My K3 is serial number 1210 and further reading of the K3 owners manual shows: "BAND0-3 provide band selection signals. Their behavior is controlled by the CONFIG:KIO3 menu entry (see below). Band data is based on VFO A. Earlier K3s may require external pullup resistors to 5 V on these lines, typically 2.2-10K." BTW, I have a KIO3A and since it is the interface to the AUXBUS and BANDDATA I would have guessed that it has sufficient drive and pullup to do the interface without external pullups. Correct? So it appears the KPA500 is reading band data rather than AUXBUS and finding a value of zero. This may be the result of inadequate pullups on the K3. I thought AUXBUS was bidirectional and the KPA500 would have been using that for its band info input. I'm soon adding a KAT500. Since the KAT500 outputs AUXBUS to the KPA500 I'm wondering if it does any buffering? If so I could pass the K3 to the KAT500 which presumably would read the BANDDATA <0-3> properly then pass it along with sufficient strength to drive the KPA500 as well as the RCS12 correctly. There aren't any schematics yet for the KAT500 to determine this. Thanks jim ab3cv ______________________________________________________________ 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
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