[NLRS] Sequencer part II

[Scott]

Sounds like a plan!  Glad you found what you need.  I too like simplicity.
My sequencer basically does the same thing (based on a capacitor charging
and then discharging).  Very easy to change a resistor for timing.  I don't
have fast on slow off, but I've allowed enough time for debounce of the
equipment relays in the IF rig and my external T/R relay after the
transverter.

Hope to work you on 10 Gig someday.  With 6 watts I should be able to feel
the air warming up when you come on frequency =:O

Scott N0EDV
Bloomer, WI

----- Original Message -----
From: <W0ZQ@aol.com>
To: <nlrs@mailman.qth.net>
Sent: Saturday, December 06, 2003 8:20 PM
Subject: [NLRS] Sequencer part II


> Thanks to all who provided recommendations for a sequencer.   I've been
> "good" this year so Santa is bringing me a 6 watt amp for 10 GHz.   My
current
> system runs 1 watt and does not use sequencing.   When I put my 1 watt
system
> together I was a bit nervous about the lack of sequencing, but its been OK
so far
> and I haven't blown any receiver inputs.   In talking with KM0T he
mentioned
> that he also did not have any problems at the 1 watt level or so but that
when
> he added more power he did blow the front end ; hence he now uses the
DB6NT
> sequencer.
>
> Thanks everyone for sending me their thought and recommendations for
> sequencers.   One thing that is obvious is that you really need to tailor
design your
> sequencer for your system for what you need it to do .... there are some
very
> good general designs that I'm sure work just fine.   For my 10 GHz
portable
> system I want to control the attack and decay times for both the antenna
relay
> and the Vcc for the 6 watt amp based on the IF rigs PTT control line.
>
> I chose to use the design by G3SEK that Donn pointed me too.   You can
find
> it at http://www.ifwtech.co.uk/g3sek/dx-book/sequencer/index.htm .   The
design
> is based on using a 6 vdc (in my case I used a 5 vdc) DPST relay coupled
with
> a series R and a parallel C time constant, and a 12 vdc DPST relay.   The
IF
> rigs PTT line controls both relays in parallel .... for my design it looks
> like the two relays together are around 150ma of current sink which should
be OK
> as the spec's for my IF rig allow up to 500ma.  The RC time constant
around
> the 6 vdc relay provides a slow ON and slow OFF while the 12 vdc relay
provides
> a fast ON and fast OFF.   Its then just a matter of connecting one pole
from
> each relay in parallel to control the antenna relay (fast ON and slow OFF)
and
> one pole from each relay in series to control the 6 watt amp Vcc (slow ON
and
> fast OFF) .... basically relay "AND" and "OR" logic.
>
> The advantage is that the design is very simple.   You can wire the relay
> poles for whatever job you need (ie; sinking, sourcing, voltage
differences,
> etc.).   The disadvantage is that the relay contact are controlling the
2.5 amps
> to the 6 watt amplifier so the relay needs to be well rated for this task
and
> contact pitting may be a longer term reliability issue .... on the other
hand
> we are talking about maybe a couple of thousand makes/breaks a year (?)
and I
> can alway replace the $5.00 relay.
>
> So, in theory, I'll be QRO on 10 GHz next year !   Again, thanks to
everyone
> for their suggestions.
>
> 73, Jon
> W0ZQ
>
>
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