Joe Subich, W4TV, wrote:
However, all three changes could have been incorporated in the K3 for
pennies in parts instead of requiring user modifications or "add on"
boxes with just a little "market research" beyond the tight-knit group
of insiders who do not push the operating envelope.
While I agree with Joe's technical analysis, the problem wasn't really
about a group of field testers who "do not push the operating envelope".
On the contrary, many of them do, in various areas. The problem was
simply that, on the issue of compatibility with existing technical
standards in the market, nobody picked up the ball.
This is another symptom of the paradigm shift that the company is having
to go through, from its origins serving the QRP community to becoming a
supplier in a much wider market. Many of these new customers will be
integrating the K3 into existing stations, and will not be pleased by
the incompatibilities of the ACC interface.
1. Reverse polarity on the ALC input. The industry standard is a
negative-going voltage because that made perfect sense in the era of
tube rigs when it was first introduced. Most solid-state transceivers
convert the ALC input to a positive-going signal for internal use, but
they don't attempt to buck the negative-going interface standard.
In the K3, the ALC input appears to connect through to the input of an
ADC, whose data sheet specifies an absolute maximum of 0.3V in the
negative direction. If someone connects a normal negative-going ALC
signal to this input, there is a risk of internal damage.
2. Reverse logic for the TX inhibit input. The standard here was set by
Yaesu (TTL or open-collector input to the transceiver, logic 1 to
inhibit TX, logic 0 to enable). Originally this facility was provided as
an the interface to Yaesu's own-brand amplifiers; but third-party
providers have adopted it too, which is how such standards come to
exist.
In the K3, this incompatibility could be easily fixed by a config
option.
3. Reverse logic in the band data output. Again, this 4-bit encoding was
originated by Yaesu, and has since been adopted and extended by a range
of third-party providers. The standard band data output is TTL, logic 1
= 5V, logic 0 = 0V.
The K3 uses industry-standard band encoding, but the output interface is
not standard. Use of open-drain pulldowns in the K3 means that existing
non-Elecraft band data interfaces will not work without some
modifications and a user-provided positive supply rail.
Whether or not any of those interface facilities is "really needed" is a
side issue. Those interfaces exist in the K3, so the relevant discussion
is about compatibility with users' existing stations.
At the technical level, these are all fairly trivial problems. My
holiday project was already going to be a breakout box for the 15-way
cable from the ACC connector, where the interfaces with several
different parts of the station can be patched in. The inverters and
level shifters that will be needed to give the K3 an industry-standard
interface to the outside world can go in there. It's just a little more
work than anyone would really have wanted.
--
73 from Ian GM3SEK
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
