[Elecraft] KPA1500 ATU - ability to handle more than two antennas

[K9MA]

I don't think it's desirable to have the amplifier controls external 
antenna relays.  One might sometimes want to operate barefoot.  Besides, 
there are external antenna relay boxes available, as well as 
programmable controllers.  (And a few of us dinosaurs are using homebrew 
antenna controllers.)  In any case, an external controller can easily be 
made to switch antenna relays, bandpass filters, etc. Another advantage 
of doing all the antenna switching external to the amplifier is it 
allows using a single coax, which can easily be disconnected when 
there's lightning about.

If one already has the antenna switching and control set up, the ONLY 
new thing the amplifier has to do is to be able to switch the ATU among 
2 or more sets of parameters for each band, and have some way the 
external control system can tell the amplifier which set to use.  My 
preference would be some logic inputs to the amplifier, say 3 bits, 
which would allow 8 sets of parameters for each band.  (That might be 
excessive, but maybe not for some of the big muli-multi stations.  I'd 
settle for 2 bits, or even 1.) Using a serial port forces the user to 
use either a computer or a controller with a serial port, not compatible 
with simple homebrew systems.

My system, for example, has a toggle switch to select one of my two 
tribanders.  I can switch back and forth several times in a second when 
trying to determine which direction the signal is coming from.  I can't 
possibly manipulate more than one switch that fast, nor to I want to 
have to reach over to wherever the amplifier happens to be, and I 
certainly don't want to be messing around with a mouse.  (While all this 
antenna switching is going on, the other hand is running the radio.)

73,
Scott K9MA


On 1/26/2018 16:25, Matt NQ6N wrote:
> I think this is a very important aspect of station design and a big 
> consideration for any future amp purchase I make.
>
> I'd like to respectfully suggest that Elecraft consider designing a 
> bulletproof 16x2 antenna switch rated for 5KW and 10:1 SWR (and lots 
> of isolation between ports) that integrates seamlessly with the amp 
> and tuner.
>
> There is typically a need to switch both antennas and high power 
> bandpass filters, or at least the high cost of high power bandpass 
> filters makes using only one for each band (via switching) very useful.
>
> So when the amp QSYs to 40m the ideal scenario allows the switching in 
> of a 40m bandpass filter after the amp, and then whichever antennas 
> are usable on 40m, with the tuner knowing which antenna was chosen so 
> that it can switch to the previously known settings for instant TX.
>
> 73,
> Matt NQ6N
>
>
>
> On Fri, Jan 26, 2018 at 1:45 PM, K9MA <k9ma at sdellington.us 
> <mailto:k9ma at sdellington.us>> wrote:
>
>     How about using an external switch to select which ATU settings
>     the amp uses?  Perhaps with a digital INPUT line?
>
>     Scott K9MA
>
>
>     On 1/26/2018 11:15, Wayne Burdick wrote:
>
>         This is definitely doable from the amp. All it takes is an
>         external antenna switch with a control port compatible with
>         RS232, Ethernet, USB, or one of the amp’s multi-purpose
>         digital output lines. (These have other uses, too, such as SWR
>         alarm output.)
>
>         To select among antennas from the amp, you could do any of the
>         following:
>
>         - tap the ANT switch to go between two or more antennas in
>         rotation
>
>         - tap ANT then use the UP/DN switches
>
>         - assign two frequently-used antennas to the front-panel PF1
>         and PF2 switches
>
>         In all cases, the LCD would show your selection from among N
>         external antenna jacks.
>
>         We can adapt the firmware to handle any such scenario.
>
>         Wayne
>         N6KR
>
>
>             On Jan 25, 2018, at 7:58 PM, K9MA <k9ma at sdellington.us
>             <mailto:k9ma at sdellington.us>> wrote:
>
>             I'm concerned about the same issue:  Multiple antennas on
>             one band. I have an automated antenna selection system. 
>             In addition to following the band data from the
>             transceiver, there are switches to select antennas.  I
>             frequently have to very quickly switch antennas, so it
>             must involve only a single switch.  Using a mouse with the
>             computer is nowhere near fast enough and I really don't
>             want to make it dependent on the computer, anyhway. 
>             However, my antennas have different impedances, so require
>             different ATU settings.  So, how can I tie the KPA1500 ATU
>             into my antenna control switch so it automatically
>             switches settings?  All the antenna switching is external
>             to the amp, so only a single amp output is used.  The
>             ideal would be a control line to the amp, controlled by
>             the same switch that selects antennas, which would select
>             ATU settings. I really don't want to make it dependent on
>             the computer.  I expect others have the same issue.  Can
>             the KPA1500 be made to do something like this?
>
>             73,
>             Scott K9MA
>
>             -- 
>             Scott  K9MA
>
>             k9ma at sdellington.us <mailto:k9ma at sdellington.us>
>
>
>

-- 
Scott  K9MA

k9ma at sdellington.us