[Elecraft] KPA-1500 wish list

[K9MA]

Bill is touching on an issue I've raised before: A way to select 
multiple ATU settings for the same frequency and antenna output. I had 
to build a tri-band tuner to switch between my two tribanders so they 
would both present the amplifier with the same impedance. The internal 
ATU would have been able to do that, if only there were a way to store 
and recall two different sets of settings. In the case of automated 
antenna switching systems like mine, there also has to be a way to 
electronically tell the amplifier which settings to use: Having to press 
a front panel switch is not acceptable, as that would require two 
operations to switch antennas, which is way too slow. (I sometimes have 
to flip the antenna switch several times during a call to determine 
which antenna to use.)

73,
Scott K9MA



On 11/19/2019 13:02, K8TE wrote:
> Another issue not explicitly mentioned is using an external antenna switch
> with different conjugate matches already trained withing the KPA1500 ATU.
> Those different matches mean when one selects a "new" (different) antenna
> than already selected on a particular frequency (same band or not), the
> KPA1500 doesn't know this fact until power is applied.  Then, due to a high
> VSWR, the amplifier faults.
>
> With just two antenna ports on the KPA1500, there are only two quickly
> accessible tuning solutions per frequency if using both ports.  If using
> only one port and an external antenna switch, a common choice in many
> stations, finding the correct tuning solutions can't be done fast enough to
> prevent a fault.
>
> As alluded to in previous messages on this topic, perhaps the solution,
> unfortunately, is an external box that could contain the appropriate data so
> that, when a new frequency/antenna combination, that has a previously tuning
> solution, is selected, the external box will tell both the KPA1500 ATU to
> select the appropriate solution and transceiver to make appropriate power
> level adjustments, both PRIOR to actually transmitting.
>
> This is done (approximately, but with no power level changes) by the KAT500
> in selecting one of the three antenna ports and the appropriate tuning
> solution.  This assumes no other antenna choices on each of the three ports
> for the same frequency.  The KPA1500/K3S combination is (currently) not
> sufficiently "smart" to accomplish this.
>
> Of course, if we had "perfect" antennas that provided resonant matches on
> all bands/frequencies, we wouldn't be discussing this.  If we had those, we
> wouldn't need the KPA1500 ATU either.  73, Bill, K8TE
>
>
>
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-- 
Scott  K9MA

k9ma at sdellington.us