[TenTec] OMNI VI and fast switching amp hook up ?

Sun Dec 4 08:37:46 EST 2005

You can install a second vacuum relay that most likely has the same pick
time as the first relay and use this for the QSK timing.  Or better yet use
a relay that is just a tiny bit slower for the txen txout return path.  The
radio shack 12 volt spdt relays have a 10 msec pick time.  This would work
to be used just as a timing relay.

Carl Moreschi N4PY
Franklinton, NC
----- Original Message ----- 
From: "Hank Phillips" <aa4hp at titustek.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Saturday, December 03, 2005 11:46 PM
Subject: Re: [TenTec] OMNI VI and fast switching amp hook up ?

> Carl and the Group,
>
> I agree that this is an excellent strategy if you have that illusive
unused
> contact which usually does not exist in fast vacuum relays.
>
> Can you give me a supplier for a dpdt/spst (minimum 5 contacts total)
> vacuum relay that has a closure speed of under 6 milliseconds?  If so,
I'll
> install it in my amplifier.
>
> For those of you contemplating the modification of an amplifier for QSK, I
> recommend contacting the folks at Gigavac at the following URL:
>
> http://www.gigavac.com/products/relays/ham/index.htm
>
> They are Ham Friendly and make a good product.  If you don't want to make
a
> 26 (or higher if you subscribe to switching faster) volt supply to modify
> your amp for vacuum relays, they will supply a vacuum relay with a 12 volt
> coil.  At a 6 ms closure time, if you can solve the timing problems we
have
> discussed here, it will be more than fast enough.  Their DPDT relay is
> significantly slower at 15 ms, a tough haul on full QSK cw.
>
> The premier model for full QSK amplifiers is the old Alpha 77.  In that
> machine, the closure of the output relay is sensed at DC level, compared
to
> the presence of RF drive (as a disable signal),  and fed back to control
> the closure of the input relay, completely preventing hot switching in the
> amp.  That was, and still is, the finest amplifier ever made.
>
> Let me know if anyone can duplicate that capability in a non TEN-TEC amp.
>
>
> 73,
>
> Hank
>
> AA4HP
>
> At 09:05 PM 12/3/2005 -0500, you wrote:
> >Hank,
> >
> >Let TXOUT pick the antenna relay of your amplifier.  Then also have TXOUT
> >wired through an unused normally open contact of the amp antenna relay.
> >Then bring TXOUT back to the Omni VI TXEN line through this normally open
> >contact and you have everything just fine.  Now with this setup the Omni
VI
> >cannot transmit without both TXOUT active and the amp antenna relay
picked
> >or energized.  There is really no solid state components to fail in this
> >path.  You may need a diode on TXOUT so it can be used to both pick the
> >antenna relay and return to TXEN for isolation on this path.
> >
> >This is exactly how a QSK amplifier is wired for the tentec txen txout
> >scheme.
> >
> >Carl Moreschi N4PY
> >Franklinton, NC
> >----- Original Message -----
> >From: "Hank Phillips" <aa4hp at titustek.com>
> >To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> >Sent: Saturday, December 03, 2005 6:53 PM
> >Subject: Re: [TenTec] OMNI VI and fast switching amp hook up ?
> >
> >
> > > Lots of good comments on the reflector already, but I will pass along
my
> > > observations.
> > >
> > > Getting an amplifier to close relays quickly enough is not a problem,
> >maybe
> > > even without resorting to the vacuum relay speed-up circuits.  Even
> > > sequencing them to close and open in the correct order is relatively
easy,
> > > depending on the relays you have available.  All of this has been
covered
> > > in excellent detail by Rich Measures, AG6K and others.
> > >
> > > Background:
> > >
> > > When you go key down on the Omni 6+, after some setup delay in the
> > > transceiver, the "TX OUT" line on J-1 goes low (to ground).  When the
> > > factory jumper is installed, it pulls "TN ENABLE NOT" on J-2 down and
the
> > > transmitter goes on the air.
> > >
> > > This is important:   In my Omni 6+, if you pull "TX ENABLE NOT" down
on
> > > J-2, no matter what the state of the operator's mind or the condition
of
> > > the remainder of the station, the transmitter goes on the air.  This
> >allows
> > > a failure external to the transceiver to put Omni into transmit, even
> > > though that may not be what you had in mind.
> > >
> > > I believe the optimal solution would be for the Omni to go into
transmit
> >if
> > > both J-2 and J-1 were driven low, that way only a response to the Omni
> > > transmit request would put the transmitter on the air.  That would
require
> > > additional logic in the transceiver.
> > >
> > > I tried to the "Y-cable" trick, and the Omni didn't like the pull-up
> > > voltage on the opto-isolator I ground to key the amplifier.  You might
be
> > > able to get around that with either an emitter-follower or FET input
to
> >the
> > > amplifier that didn't confuse the existing Omni signalling.  Another
> > > possibility might be to pick off the collector of Q-16 and bring it
out to
> > > an external connection, and you could still keep the TXHang
> >programmability.
> > >
> > > Anyway, I wimped out before solving the problem, settling out of court
for
> > > the relatively inoffensive built-in relay.  If anyone nails this, I
would
> > > like to hear your approach.
> > >
> > > Very 73,
> > >
> > > Hank
> > >
> > > AA4HP
> > >
> > >
> > > At 01:59 AM 12/1/2005 +0000, you wrote:
> > > >Hi-
> > > >  I have an OMNI VI and a TL-922a amp which I just finished wiring
with
> > > > vacuum relays for QSK fast switching. Works great but, the OMNI
relay
> > > > used to key non Ten Tec amps is annoying on CW. (Not real annoying
> >but....)
> > > >  Of course when not using the amp, which is 99.9% of the time I can
> > > > switch the relay off and have quiet CW.
> > > >  Is there any reason why I can't tap into the TX EN and TX OUT
jumper
> > > > with a "Y" connection and run the quiet transistor switching to
ground
> > > > since TX OUT does go to ground when its active and then leave the
relay
> >OFF?
> > > >
> > > >73 de Dave in NH  K1OPQ
> > > >
> > > >_______________________________________________
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> > >
> > >
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