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.
73,
Don W3FPR
On 2/28/2018 11:15 AM, Joe Subich, W4TV wrote:
> THe point is that the two do not work together.
The point is that the devices don't work together because the third
party manufacturers did not bother to understand the Yaesu design
and take the necessary steps to be compatible. Yaesu's only purpose
was to provide band switching data from the transceiver to a Yaesu
amplifier. Their was no reason to design their system according to
some inapplicable "standard" from the data processing world.
Third party manufacturers need only provide a low impedance source
of +12V for a logic high and open circuit for a logic low on the
"transmit" side to emulate the Yaesu transceiver.
On the receive side, any device that would connect to a Yaesu
compatible transceiver needs to tolerate +12V on the input and have a
moderately
high (1 - 2K) pull down on any logic inputs (if it uses logic inputs);
opto-isolator inputs simply need the appropriate current limiting
resistors for 12V inputs (or +5V inputs given that many transceivers
have failed to provide +12V logic high outputs).
The bottom line is that this is not a "standards based" application.
If one is going to provide (or use) BCD "band data" the device must
closely emulate the Yaesu transceiver or clearly state that its
signaling levels are not [guaranteed] compatible with Yaesu.
73,
... Joe, W4TV
On 2/27/2018 10:53 PM, Don Wilhelm wrote:
Joe,
You do admit that many amateur products do not conform to typical
communications standards in the digital world. My experience does go
back to my design and evaluation of IBM terminal communication
between a DCE and a DTE device. Although this was not necessarily
RS-232 levels, the same thing is true. The drivers provide the low
and high levels to the line (an open circuit or a ground) while the
receiver at the far end of the line provides the logic high level.
All other receivers will not provide voltage, but can listen in on
the communication. This is not consistent with amateur products with
one providing pullup resistors ath the driver location and some
receive locations requiring the opposite I.E, those providing pullup
resistors to +12 volts.
THe point is that the two do not work together. It is not a systems
approach.
73,
Don W3FPR.
On 2/27/2018 10:09 PM, Joe Subich, W4TV wrote:
You're dealing with a "standard" that was originally developed for use
only within one company's products - much like Elecraft's Aux Bus.
As such, any "industry standard" is moot. The design is for active
high/voltage source (to +12V originally) and was not intended for any
purpose than providing band switching for the FL-700 then the Quadra.
It would seem to me that any product that claims to inter-operate with
the Yaesu "Band Data" would emulate or at least be compatible with
that behavior - including the ability to *source* sufficient current
at +12V.
These devices are not operating in the "communications (non-ham)
world",
they are strictly amateur products.
73,
... Joe, W4TV
On 2/27/2018 9:28 PM, Don Wilhelm wrote:
The problem is that most devices (in the ham world) expect the
driver device to provide voltage.
In the communications (non-ham) world, the expectation is that the
driver device produces either a logic low (short to common) or a
logic high ( open circuit).
Look at the data sheets for "line drivers" and "line receivers" to
check out what I am saying.
Open collector or open emitter does not make a difference in
function, it is only a circuit design decision. Yes, open
Collector (or open drain) is commonly use in logic where the active
state is zero volts (transistor or FET conducting to ground).
The open emitter design is the opposite. A conducting device will
provide a voltage on the line (or signal) being driven.
The point is that in a properly designed communications system, the
drivers provide either conduction to ground or an essentially open
circuit to the communications line (think of a relay being either
open or closed). The receiver provides the voltage to detect
whether the driver is in an open circuit or closed circuit state.
If there are multiple receivers in the system, only one can be
"boss", and that one determines the open circuit voltage and
contains the pullup resistors for the system. Other receivers work
in listen mode and will contain no pullup resistors or active drivers.
This whole situation goes back to the "one driver, one receiver"
condition.
Only one driver can exist on a communications system without conflict.
Multiple receivers are possible, but only one (at the far end of
the line) should provide the pullup resistors. All other receivers
must be only in the listen mode.
73,
Don W3FPR
On 2/27/2018 8:06 PM, Joe Subich, W4TV wrote:
> But many (most) ham devices do not do it that way, they expect the
> pullup resistors will be provided by the driver gear.
Actually, most devices that use BCD "band data" expect an open
emitter driver not an open collector driver. Open emitter will
*source* voltage for logic high and be open circuit for logic
low. This is the convention from the early Yaesu rigs which
were the first devices to support "band data" (it is the way
the FL-7000 and Quadra amplifiers operate).
You will find the W9XT BCD10/BCD14 decoders with their opto-isolator
inputs work just fine with the "open emitter" drivers. Other devices
designed with Yaesu transceivers in mind have appropriate current
limiting (series) on the input lines and "pull down" (parallel)
resistors on the logic gates. Some "standard" devices (Top Ten
BD-Y and the original microHAM Band Decoder) will provide both
current limiting resistors and internal pull-ups but I have not
seen any amateur product with series diodes in the band data lines.
73,
... Joe, W4TV
On 2/27/2018 4:17 PM, Don Wilhelm wrote:
Knut,
That is the way it *should* be, and was that way in the K3
originally.
But many (most) ham devices do not do it that way, they expect
the pullup resistors will be provided by the driver gear.
So, because of that, Elecraft added pullup resistors to the band
data outputs of the K3 long ago.
So yes, we are left with a situation that often requires steering
diodes.
73,
Don W3FPR
On 2/27/2018 3:48 PM, ab2tc wrote:
Hi Don and all,
Hear,hear, Don. The receivers should have the pullup resistor to
whatever
the appropriate voltage needed (within reason) *and* a steering
diode in
series with the input. This will prevent another device with a
higher
voltage from feeding current back into the device which could
damage
semiconductors. Without the steering diode all receivers must
use the same
pullup voltage. Of course a single receiver is not a problem
either.
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