[Elecraft] KPA500 and KAT500 Ports

Wed Jul 13 20:25:08 EDT 2011

I admit, I have a dog in this fight but I see the calls for all manner
of add-on antenna switching hardware for the KAT-500, and/or KPA-500
as more than a little lily gilding ... and too much cost/effort for
very little benefit.

1) antenna switches *after* a tuner are problematic to start with.
    The switch/relay needs to be designed to handle a substantial
    excess voltage and excess current if it is to be reliable at
    high SWR.  Some of that can be mitigated by limiting the power
    levels (e.g., 600 W from the KPA-500) but I've already seen posts
    where US stations want to be able to handle their "legal limit"
    amplifiers.

    Realistically, at even 3:1 SWR that a couple KV and/or nearly 10A
    on peaks.  Relays to handle those levels with good impedance match
    and reliability don't come cheap.

2) there is no way that any antenna switching logic built into the
    K3, KPA-500 or KAT-500 can provide switching for multiple antennas
    per band ... perhaps the ANT1/ANT2 logic of the K3 can be hijacked
    *IF* the second antenna port of the KAT-3 is disabled but that
    still limits the choice to two - not three or more antennas as
    some have expressed a "need" for.

3) there are another group that express a need for "matrix" switch
    capability ... to be able to select and route multiple antennas
    to multiple transceivers, possibly with the option to select one
    amplifier for each transceiver from among a pool of amplifiers.

4) adding the ability to switch any of several antennas to either
    of two antenna ports or the K3 or KAT-500 is a prime example
    of lily gilding ... particularly since both antenna ports are
    not used at the same time.  However, that switching capability
    is already available in "SO2R" antenna switches from several
    sources - it only takes a little bit of decoding the K3 DIGOUT1
    and band data lines if one were so inclined.

All of these, and other "wants" are nice on their own but not as a
"standard" capability for the K-line.  Most of the wants can/should
be satisfied with already announced/available products that deal
with antenna switching/station management.  After all, these are
system integration items/issues that are not specific to the K3,
KAT-500 or KPA-500 ... integrating the capability into those products
increases their cost for all users *and* limits the use of those
capabilities to those with the Elecraft specific hardware.  Any good
businessman will tell you that increasing cost and limiting the
market are a bad combination ...

Much of this reminds me of someone trying to renovate a kitchen in
the morning and restore a classic car in the afternoon and expecting
Craftsman or Kobalt to provide them a single "Swiss army knife" with
all of the tools to do both jobs.  It's neither practical nor logical.

73,

    ... Joe, W4TV

On 7/13/2011 7:22 PM, Brendan Minish wrote:
> I think that 2 Antenna ports on the KAT500 is a good fit, after all 2
> ports is what the K3 (+ATU) has so many of us have configured our
> stations to work with this configuration
>
> I would suggest however that there be an (optional?) module (s) for the
> KAT500 that provides for sink or source outputs, one per band (plus a
> few more?) that can be further configured via software to to clever
> things (like selecting 2 different antennas for 80/75m, or multiple
> bands on one antenna )
> It would be even nicer if this was duplicated for the second antenna
> output either in the same module or as a second user installable module.
>
> These would be driven by the auxbus data that will presumably be fed to
> the KANT500 and decoded by it's CPU anyway.
> An input (per antenna port) that can be used to indicate to the KAT500
> that the requested antenna is not available might also be a good idea so
> that the KRC500 can then select the second choice on the other port
> (complete with recalling the last used tunings for the secondary ) would
> also be nice.
>
> Think of this as the functionality of (2x ?) KRC2's built in and it
> would make for superb versatility since the KRC500 could then be
> configured to automate pretty much any external automatic antenna
> switching arrangement.
>
> I don't know if this is practical to fit into the box but it sure would
> be nice.
> The KRC2 may already form the basis for much of the required
> circuitry/firmware.
> The Sink/source outputs could be selected sink/source by internal jumper
> and the output could be on DB15 or DIN connectors to minimise rear panel
> real estate. (perhaps with pre-made breakout cable supplied )
> Another option might be to have the 'Glue' internal to the KPA500 and
> the Sink/source drivers in a 'dongle' to conserve internal space and
> provide for easier breakout.
>
> 73
> Brendan EI6IZ
>
>
>
>
> On Tue, 2011-07-12 at 15:34 -0700, Eric Swartz - WA6HHQ, Elecraft wrote:
>> Hi Gary,
>>
>> Having 4-5 RG8 antenna cables, plus the input cable, hanging out the
>> back of the desktop ATU is both likely to pull the ATU off the desk, and
>> will easily not fit in the box size we are planning. It also adds a lot
>> of complexity and cost to the basic ATU in order to accommodate more
>> connections with the needed isolation etc. We certainly do not want to
>> price the ATU out of the range of most hams, or make it too large.
>>
>> Many of us use manual or automatic switches external to the amp / tuner
>> to provide these functions.
>>
>> A much better solution for those needing more than two auto-selected
>> antennas is to use an external relay switch box, controlled by the
>> radio. This has the advantage of getting the cables, clutter, and
>> switching network off the desktop and either under the table or outside.
>> There are certainly a number of external antenna switches out there that
>> can do this, but if we offered something that was tightly integrated
>> with the K3 (and KPA500/KAT500) as a product, what features would be
>> desirable? (Number of antennas, rigs inputs, switching options etc.)
>>
>> 73, Eric WA6HHQ
>>
>> ---
>> www.elecraft.com
>>
>>
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