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

Sat Dec 3 23:46:49 EST 2005

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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