[Elecraft] KAT500 power question

[Jack Brindle]

Godo questions. The power sequencing key is that the KAT500 must be powered before the K3 initializes the Auxbus. You actually have a little bit of time after the K3 powers on before this happens, and the KAT500 powers up quickly to wait for this activity, so if you were able to power the KAT500 from the K3’s power jack, it will work just fine. I do this in my own station by powering a relay from the K3. The relay then switches power to the remaining peripherals, including my KAT500, K3  and  KRC2. I can’t answer the question as to whether the upgraded K3 can directly power a KAT500 - my own has not been upgraded and with the power setup I have I don’t need it.

As for the KRC2, we have not seen any problem of this sort so far (and it has been a long time…). The KRC2’s Auxbus circuitry is slightly different from the KAT500, which seems to allow it. Before anyone asks, the KPA500 does not have this problem at all. It only transmits on the Auxbus, and the isolation driver transistor it uses very effectively prevents any problem.

As for the interconnect, I highly recommend using the Auxbus connection, especially if a KPA500 is in use. When properly configured, the three devices work very well together to provide an excellent user experience. To borrow a phrase, they just work.

73!

Jack B, W6FB

> On Oct 4, 2014, at 6:59 PM, Wes (N7WS) <wes at triconet.org> wrote:
> 
> Let me clarify some issues before leaving this subject.
> 
> 1) There are apparently multiple versions of the manual that show different KAT500 power requirements.  The current one, Rev C, states on page 2 that the voltage should be 11 to 15 VDC at a current of 1.0 A max (200 mA typical).
> 
> 2)  A modified K3 will output 1.0 A. See *K312MDKT.
> 
> 3) *After further digging I see the warning that if the K3 and KAT500 are interconnected via the AUX bus, the KAT500 must be power before the K3 is or *the K3* won't initialize properly. (p 14)  So there is my integration/timing issue.  Imagine having to have your printer powered up before booting your computer to avoid latch-up. Does this mean that other peripherals (KRC-2) hanging on the AUX Bus will have the same effect?
> 
> 4) On a positive note, it went together nicely (not too pleased with the paint on the top cover) and seems to work fine using just the K3 without interconnects, just r-f sensing.  The clattering relays are a little frightening though when my only prior experience with autotuners was the quiet whirring of the motors in my TS-870SAT.
> 
> Wes, N7WS
> 
> 
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