So i think I sent my previous email before reading this through, sorry
about that!!
In receive, the amp output jack is connected through the T/R relays to the
input jack. The RF sensing circuit comes from the input so **IF** there is
a large amount of RF being coupled from one antenna to another, it is very
possible that the amp may try to key if the jumper between 5 and 6 are left
in.
So the safe answer is to cut the jumper between pins 5 and 6. Removing the
two diodes that rectify the RF into DC will also render the RF sensing non
operational although a bit overkill.
Terry Price - W8ZN
Directive Systems and Engineering
703-754-3876
On Sun, Dec 15, 2019 at 6:30 PM John Young via VHFcontesting <
vhfcontesting@contesting.com> wrote:
>
> Taking pin 2 to ground turns on the PA with 5 and 6 still internally
> connected.
>
> However with 5 and 6 internally connected the rf sensing is still enabled
> which defeats part of the purpose of the sequencer. The amplifier can turn
> on if RF gets to it even if the PTT ground to rf amp lead from the
> sequencer is not grounded.
>
> I have had my 991A on 6m buzz my 1.25m amp, same thing happened with the
> W4IY Elecraft on 6m in september. If I had been using a hard keyed pre amp
> on 1.25m it would have been fried.
>
> I opened up the amp and there is no obvious sign of the pin 5-6 internal
> shorting wire. Maybe you have to cut a trace now?
>
>
> Calling TE Tomorrow.
>
> 73
> John
> KM4KMU
> On Sunday, December 15, 2019 John Young via VHFcontesting <nosigma@aol.com>
> wrote:
>
> The TE manual gives some simple instruction for hard keying the amplifier
> but out an abundance of caution I want to verify my understanding of them
> before I start cutting wires and adding relays.
>
> The DEMI sequencer gives a sequenced PTT ground to enable the amplifier.
> The TE instructions are to cut the internal shorting wire between pins 5
> & 6 and then connect the PTT ground to pin 2.
>
> To enable the RF amplifier the TE instructions are: 1) Connect pin 5 & 6
> then 2) connect pin 2 to PTT ground.
>
> My interpretation of these instruction are:
> I need to use the PTT ground to close a relay that connects pins 5 & 6 and
> then use an output from this relay to close another relay that connects the
> PTT ground to pin 2 on the amplifier.
>
> Is this correct?
> Is there a better way?
>
> 73
> John
> KM4KMU
>
>
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