[Elecraft] KAT500 assembly

[Don Wilhelm]

George,

Yes, the current from the K3 12V output is limited to 500 ma. for older 
K3s and 1 amp in later K3s.  Older K3s can be upgraded with the Elecraft 
kit to provide 1 Amp capability.

The KAT500 spec maximum draw is determined by how many relays are being 
activated by any particular antenna solution, so I would use the maximum 
value for the design point because you do not know which L/C 
combinations will be necessary for any particular antenna, and yes that 
maximum is greater than what the K2 12V output can supply (even with the 
upgrade).

I would suggest that you power your KAT500 directly from your power 
supply rather than trying to use the K2 12 volt output.

If you wish to use the K3 12 volt output so the power to the KAT100 (and 
other accessories) would be powered on when the K3 is turned on, I would 
suggest that you use the K3 12V output to drive a relay, whose contacts 
in turn provide power to those accessories (KAT500 included).

Safety note - install fuses in each power cord (near the power source) 
with the fuse rated at 1.5 to 3 times the maximum expected current draw 
by that device.  In-line fuseholders can be obtained an auto parts 
store.  I prefer the ATC-3 blade type fuses, but YMMV.

73,
Don W3FPR
On 6/6/2014 4:07 PM, GDanner wrote:
> My understanding is the KAT500 will overcurrent the K3 Aux DC output.
> The KAT500 specification is 1.5A max (200 mA typ) from my IB (page 2 
> Rev B3 Nov 20, 2012. The 200 mA should be ok but the 1.5A is greater 
> than the K3 1 amp mod is rated for.
>
> I power my KAT500 from my station power supply. Therefore it comes on 
> prior to the K3; as required by the KAT500 IB (page 3 item 2 under 
> Elecraft K3 Transceiver and KPA500...).
> Also see !IMPORTANT: note on the top of page 10 - "If you are using 
> the KAT500 with an Elecraft K3 transceiver connected using the DB15  
> cables as shown I Figure 1 or Figure 2, you must apply power to the 
> KAT500 before turning the K3 on.
> 73
> George
> AI4VZ