[NLRS] More on sequencers

[Dr. Gerald N. Johnson]

On Mon, 2006-03-27 at 17:25 -0600, Chris Elmquist wrote:
> On Monday (03/27/2006 at 05:15PM -0600), Dr. Gerald N. Johnson wrote:
> > 
> > You run key and PTT leads to the sequencer and don't run VOX. You run
> > the rig keying line from the sequencer to the rig which gets keyed at
> > the last stage of the sequence. E.g. you run microphone and key through
> > the sequencer.
> 
> OK.  Understood that you do not INTENTIONALLY run VOX...  but looking
> at the front panel of my FT-736, there is a huge VOX button just asking
> to be accidentally pressed as one example.

That is a case of rig design not believing it has to fit with anything
else. 
> 
> I know I am being picky-- but I am trying to draw out the more elegant
> solutions which solve this problem in the general case.

I don't know of any elegant solutions. I do know such a slip on my
FT-726 years ago melted the GaAsFET in my 2m preamp when I keyed up on
FM. The external key line in the 726 come from a relay, but the RF is
keyed by DC direct the key out line has 5 to 10 milliseconds delay from
RF. Truly obnoxious with external stuff.
> 
> A sequencer that has a dummy load in it-- to take any RF that comes out
> of the IF rig until all the sequencing is done seems close to my ideal
> solution perhaps.  Then you are down to just racing the one relay that
> switches the dummy load across the IF rig's output.

If going to a transverter that needs milliwatts, then one can delay the
transverter keying until last and let the initial output from the 736
dump to the attenuator/dummy load on the transverter, but still give the
amplifier and preamp relays time to seat before hitting them with RF.
But that doesn't solve the PA/preamp protection needs on the bands not
needing a transverter.

I'll have to check, but I think the control outputs (by band) from the
736 essentially are simultaneous with RF output in CW (KOX) or FM modes.
There's often a delay on SSB with manual PTT, but its not guaranteed
that we will wait for the PTT button to hit bottom before shouting at
DX.
> 
> Thanks.
> 
> Chris NØJCF
> 

It might be drastic, but probably only a couple wire cuts inside the
radio could prevent the KOX, VOX, and front panel buttons from working.
Then those functions need to be implemented in the sequencer whose last
output turns on the exciter. That's as elegant as I can get today. Be
sure that the characteristics of the exciter have caused much cursing in
the past and unless cure will do so in the future. And what works for
one model doesn't help another model. The custom built exciter probably
has the versatility though, but the bands would be very quiet if the
only successful rigs were home built.

-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer