[Elecraft] Any way to automatically bypass K3 ATU when using KPA500?

[Guy Olinger K2AV]

There are a lot of engineering issues in a choice to do it with a unit
switchout.  It's not clear that a 5 inch piece of coax has less loss than 5
inches of printed circuit board, so presuming extra loss with the tuner
going into "neutral" is not warranted.  Constant routing through the ATU
saves two relays, and whatever is necessary to drive them, thus saving
space, saving cost, and removing two possible failure points.  And one of
the antenna possibilities is that on a particular frequency, that the
antenna will present 50 ohms resistive, while other frequencies on the same
band and antenna require kicking in coils and/or caps.  So the 50 ohms
resistive setting, for all purposes a bypass, has to be in the ATU's
toolbox.  Bypass on the K3 just means set the ATU internal path and
connections at the 50 ohms resistive setting and leave it there.

Loss at this point is probably irrelevant any way.   Using the KPA500, you
would be setting the K3 power level to bring the KPA output to your chosen
level, and any loss or lack of it in the ATU path is simply accounted for
by where you set the power knob.

73, Guy.

On Fri, Jun 15, 2012 at 9:14 AM, <AC6JA at aol.com> wrote:

>
> Of course the KAT500 is on order! I placed my order over the phone the
> first day it became available, hihi!
> I just think the internal K3 ATU should not be tuned into the theoretical
> 50 ohm input of the KPA500. Aren't there internal losses through the ATU
> components that don't need to happen if the tuner is bypassed?
> I "assume" a firmware change could allow the ATU status to follow the OPER
> and STBY modes like the different power levels?
> Just wonder how everyone else has their K3/KPA500 set up?
>
> Mike AC6JA
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