Dave,
Explaining my findings will be
difficult via email, but I'll try.
The FT-736 presents some obstacles
to making the sequencing foolproof.
To make any system foolproof we
should sequence the system in the following order:
Pressing the mic PTT starts the
sequencer events.
Event #1 - Bypass the preamp
Event #2 - Key amplifier
Event #3 -
Event #4 - Key transceiver to apply
RF. (Most new rigs have an a port that can be used to hold off all RF
until an external signal is applied. Unfortunately, the FT-736 doesn't
have this valuable circuitry)
I asked the Moon-Net forum for any
suggestions on sequencing the FT-736 and got many replies and
solutions. Most are simple and only require a modification to the mic
to place its PTT in series with the sequence's Event #4, allowing Event
#4 to be routed to the rig's mic input. These solution will not allow
CW operation.
Others were footswitches and
external PTT buttons mounted on the desktop and these allowed CW to be
used.
The real problem, and this is where
is becomes non-foolproof, is the MOX (Manually Operated Transmit)
button on the front panel of the FT-736. It will not start a sequence
and will immediately apply RF to the system and burn the preamp out. I
have seen this button used in normal operation and it has made me
kringe.
Moon-Net, provided some solutions to
that issue. The solutions ranged from disabling the MOX button to the
modification of internal circuitry to hold of RF until Event #4 enabled
it. Both of these were not diffcult, but in our case require some
approval.
Another solution is to educate users
to not use the MOX button or CW. We have the potential for many users
of the system, some may be unaware of the limitations.
I could use any help you guys can
provide.
My TS-790 sequencing is not
foolproof, but I put it together and know its limitations and have so
far avoided catastrophy.
73
John
----- Original Message -----
Sent:
Thursday, May 21, 2009 6:39 AM
Subject:
[sarcmembers] Re: Help!...Need 220Mhz yagi for ARRL June 12-13 VHF
Contest
John
What do you need for the 736 interface. I may be able to help out.
Dave KA6BFB
John Maetta wrote:
Hi George,
Since my time before the contest is
short, I have set my own agenda for Saturday. When I get done and if
there is time, I would be glad to help wherever I can.
Here are the tasks I have to get ready
for the contest:
Repair broken element on 50Mhz yagi.
Assemble 220Mhz yagi.
Build and run feed lines for 50Mhz yagi
and 220Mhz yagi.
Assemble Cushcraft 13B2.
Test portable tower rotator.
I have the sequencer built, but I am
struggling with how to interface it to the 736. The 736 offers some
challenges to properly, safely and foolproof the switching.
John
