Re: problems integrating IC -746 as second radio into commander


Joe Subich, W4TV
 

VSEND had to go to ACC(2) because HSEND was on pin 3 of ACC(1)
already.
Icom's "PTT lines" are strange in that they are bidirectional.
Pulling HSEND or VSEND low puts the rig into transmit *BUT* if
one uses the mic PTT switch (or VOX, or Semi Break-IN CW, etc.)
HSEND (for HF/6m) or VSEND (for 144 MHz) will also "go low".

A better question might be "why did they need two PTT
lines" but I don't have an answer.
Because there are no (known) amplifiers that cover 1.8 - 144 MHz
and one typically needs a separate amplifier keying line (amplifier
PTT) for a 2 meter amplifier!

If you use the 6-pin mini-DIN "DATA" port there appears to be only a
single PTT.
That is a good solution if one has an IC-746Pro (IC-7400 in Europe).
Unfortunately, the mini-DIN6 is not present on the IC-746.

73,

... Joe, W4TV


On 2020-09-21 5:44 PM, Peter Laws / N5UWY wrote:
On Mon, Sep 21, 2020 at 4:30 PM Jim <wa3mej@qsl.net> wrote:

Update - I found something interesting. Apparently the IC-746 needs a special cable in order to use the accessory port for data on vhf. for some odd reason they decided to put vhf data (originally for packet ) on the 7 pin DIN connnector while the HF data connection goes to the 8 pin DIN. Initially I thought this strange but thinking back its not at all. THis radio was designed early to mid 90's for the packet craze. Remember we had DX
The ACC port pinouts for the IC-746Pro are on p21 of the PDF manual.
If you actually have an IC-746 you'd need the correct manual (which I
assume is online if you google hard enough). I expect the ACC ports
are the same because they are pretty much the same across Icoms, at
least the pre-USB models. VSEND had to go to ACC(2) because HSEND was
on pin 3 of ACC(1) already. A better question might be "why did they
need two PTT lines" but I don't have an answer.
If you use the 6-pin mini-DIN "DATA" port there appears to be only a
single PTT. It's truly a pity that the industry never got behind this
standard (see http://www.wa8lmf.net/6-Pin-MiniDin-Data-Connector/index.htm).
The IC-746Pro dates from about 2001. I don't believe the non-Pro was
out for more than a year or two before the Pro came out. The only
difference that I know of is that the Pro has DSP filtering while the
non-Pro requires a fleet of FL filters.

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