[sarcmembers] Sequencing the FT-736
- From: "John Maetta" <j.maetta@xxxxxxxxxxx>
- To: <sarcmembers@xxxxxxxxxxxxx>
- Date: Thu, 21 May 2009 17:25:21 -0700
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 -----
From: David Dowler
To: sarcmembers@xxxxxxxxxxxxx
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
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