On 2/28/2018 8:19 PM, Jack Brindle wrote:
It makes me wonder if perhaps the old Yaesu method should be retired
> and no longer used.
If you're willing to purchase/replace all the pre-1990 Yaesu
transceivers still in use <G>.
Either they get frustrated because the connection doesn’t work and no
harm is done otherwise, or they get really frustrated because the
12V driver blows up their device.
If the device is designed to be +12V tolerant (input current limiting
and properly selected "pull down") there is no damage. The input
current limiting and pull down also keeps any voltage on the inputs
low enough to prevent "false powering." For that matter, the BCD
signals are DC and the third party device could use shunt zener diodes
on the signal lines to limit the input voltage to and prevent false
powering. It's only when the third party device makes assumptions
without understanding the history of the Yaesu "Band Data" (or "Linear")
interface that one has an issue.
73,
... Joe, W4TV
On 2/28/2018 8:19 PM, Jack Brindle wrote:
There is a big problem with this, one that was unusual when Yaesu first created
this setup, but very common now. The issue is that of false powering of
receiving devices. In this day of low power micro controllers and other digital
devices, the device can actually be powered through the I/O port when the
device is supposed to be off. The I/O current flows into the input pin, through
the protective diode and onto the Vcc rail, bypassing the main VCC pin. This
means the device may be partially functional, and not under proper control. It
can lead quickly to the destruction of the device.
This is the big reason for modern-day communications techniques between
devices, and why protective measures must be taken to avoid false powering
other devices. Yes, devices connected to BCD band data _can_ be false powered.
We do see it. It makes me wonder if perhaps the old Yaesu method should be
retired and no longer used. I certainly won’t be buying any of those devices.
There is no reason that BCD data should not be carried at logic levels between
devices if these measures have been taken. There appears to be two separate
“standards” at this point, the Yaesu 12V system, and the 5 volt TTL logic level
system. Devices that play in each should be clearly marked so the buyer can
beware. Unfortunately many are not. This does provide an opportunity for the
creation of interfaces which translate between the two methods, providing
protection to both the transceiver and the device being driven. The problem
comes from hams who don’t realize the issue and try to connect the two. Either
they get frustrated because the connection doesn’t work and no harm is done
otherwise, or they get really frustrated because the 12V driver blows up their
device.
Luckily we don’t see the latter happen that much. But arguing that the “old
ways” are somehow better, when we know otherwise, doesn’t do very much good.
In the Elecraft case, the drive and receivers are 5-volt TTL logic levels. As
long as anything they attach do use those same levels everything works just
fine.
- Jack, W6FB
On Feb 28, 2018, at 11:33 AM, Joe Subich, W4TV <[email protected]> wrote:
On 2/28/2018 12:42 PM, Don Wilhelm wrote:
So are you advocating that all manufacturers of ham gear should adopt the Yaesu
implementation as a "standard"? Icom, Kenwood, Flex and Elecraft may have
other thoughts.
Yes, if another transceiver manufacturer chooses to emulate Yaesu's
protocol (BCD based "band data" with 160M = 1, 80M = 2, 40M = 3,
30M = 4, 20M = 5, 17M = 6, 15M = 7, 12M = 8, 10M = 9 and 6M = 10),
they should also emulate the signal levels.
Icom and Kenwood have spoken, Icom used its own proprietary "Stepped
Voltage" for the IC2KL/IC4KL and certain antenna tuners (which Elecraft
supports in the KPA500 and KPA1500), while Kenwood have never provided
any "band Data" outputs.
I don't know/care what Flex are doing in their current "radios" - their
older products could be made to properly emulate the Yaesu Standard by
running a third party software application that drove an LPT port in
the computer that did the majority of the Flex's "work" - that LPT
sourced sufficient voltage/current (in "full power" ports) to be
compatible with the Yaesu implementation.
73,
... Joe, W4TV
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