W3FPR posted:
Just as a reminder to those of you who are contemplating SO2R operation with
the K2 - the stock K2 cannot properly use PTT for steering between the
transceivers when in CW mode because the PTT line is the same as the DOT
input. If the SO2R enabled program steer CW by switching the keying, things
will work fine, but I believe there are some that key both rigs and depend
on the PTT routing to select the proper transceiver. I am investigating the
methods used by various programs right now.
As one may be using any of a variety of radios, amplifiers, antenna
switching & the like, the way it is done is by forcing the radio into
transmit mode first. Amplifiers & anything else downstream has T-R
switching driven by the radio. The logging program then goes key down
after a short period of time. The process is reversed when going from
transmit back to receive.
The transition from transmit to receive on one radio may be followed
immediately by the second radio doing the opposite (operator CQs on
one band whilst listening for replies to just finished CQ on the other).
If during the CQ on the second band a reply is heard to the CQ on the
first band, the second CQ is aborted & the logging program jumps back
to first radio.
As different radios behave somewhat differently & timing is critical,
some logging programs allow tweaking of PTT-to-key-down delay,
as well as adjustable timing for polling the radio for frequency
information (or to even not poll the radio during transmit as some
just cannot keep up with everything that is going on).
Ultimately, all the major contest logging programs implemented CW
PTT to avoid hot switching amplifiers, though there is more to it than
that.
Little things matter & add up after a while if you are running stations
at a fair clip (like 100/hour average for an entire weekend, with peaks
well over 200 - short spurts of up to six QSOs/minute are even
possible from my apartment station). Some logging programs even
vary PTT-to-key-down delays based on whether the operator is
sending with the paddles instead of from the program's memories,
optimizing timing of the station's T-R switching times whilst also trying
to minimize unnecessary T-R transitions on relays in the amplifier.
This is all done by asserting the two lines that the vast majority of
radios have - even my first station that wasn't even a transceiver
(SX-100/Viking II) - one to put the radio into transmit mode & the other
to go key-down. The three major logging programs do it this way. If
something out there achieves this functionality in another way, I doubt
you will find it in use by other than a few & most likely even fewer who
are serious about radiosport.
Like serious VHF & above work, what we do relies on being able to
_control_ T-R switching & CW keying externally - an analogy might be
T-R switching in a radio itself: various bits need to do certain things
in the correct sequence & with correct timing. Just like inside the K2
itself, switching between transmit & receive in a radiosporting station
can't really be done in any other way. This is why, although I was
thinking of something like Don has done up with the 74AC153, this
treats only treats the "symptom" by keeping CW keying from getting
to the K2 unless PTT is asserted. I look forward to the firmware fix
that addresses the "disease".
Hopefully Elecraft will include CW PTT in any future products that
might be of interest to the radiosporting segment of the market. In
the consumer electronic product industry, usually the product is
designed to interface like similar products where that product is used,
as opposed to the product requiring the consumer to adopt everything
to that product. An exception to this is SONY, but one can only get
away with being so unique if you are as dominant in the market as
they are. The amateur equipment portion of the consumer electronics
industry really isn't a good place to do mainstream products like radios
so differently, unless one wants to stay out of the mainstream (where
most of the water flows ;^).
It's good to see radiosporting applications of the K2 being better
embraced here by the Elecraft "community". Like the car one drives,
there are a lot of improvements & refinements to the product for those
with more pedestrian applications that can come about from competitive
use of the product. With the keen interest the K2 has created in the
radiosporting community, hopefully any future products might take
advantage of this interest to catch stuff like CW PTT earlier on.
73, VR2BrettGraham
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