[TenTec] OMNI VI and fast switching amp hook up ?
Tommy
aldermant at alltel.net
Sun Dec 4 06:46:32 EST 2005
I'm not sure why, suddenly, there is a perceived 'problem' with Ten
Tec radios and/or amplifiers running full QSK?
I have been doing QRQ CW for over 30 years with their equipment,
running CW at speeds in excess of 100 wpm. And I personally can not
operate CW without full QSK, be it 20 wpm or 80 wpm. I have owned
Corsair's, Omni C's, Omni 6's, Omni 6 Plus's, and Icom IC-781
transceivers. I have owned Ten Tec amplifier's only, primarily
because they have shown me to be the amplifier with the best and most
reliable amplifiers for full QSK. Probably the quickest full QSK
amplifier for full QSK is the Alpha 87A with it's PIN diode
switching, however you better make sure you never make the mistake of
keying it into a high SWR. The Ten Tec amplifiers I have owned are
the Hercules 444, Titan 425, and now a Titan 3.
Ten Tec makes full QSK, with their transceiver/amplifer's extremely
easy to configure with their TX OUT/TX EN circuitry in both the xcvr
and the amplifiers. I have never found any need at all to make any
modifications whatsoever to any Ten Tec rig or amplifier in order to
have it run full QSK at any speed I choose to operate. The QSK
circuitry, especially in the Titan 3, in very complex and very
complete. With the Titan 3, there is no possible way you 1) can
damage the amplifier, 2) can damage the xcvr, 3) can have any timing
problems at all.
Ten Tec's reputation has been built over the years as having what
most users call 'silky smooth full QSK'. That is a well deserved
reputation! The discussion of modifying Ten Tec's QSK circuitry, in
my opinion, is based upon not understanding how well it performs and
how reliable it is and has been for many years. The discussion of the
'problem' with being able to inadvertently key a Ten Tec xcvr by
placing an incorrect signal to TX EN has to be based upon one's
inability to follow Ten Tec's simple instruction's in every one of
their products manuals.
Vacuum relays can be a problem. If you run no more than about 40 wpm,
the vacuum relay's in Ten Tec amps most likely will last forever. If
you run QRQ CW full QSK, you may have fatigue failure with them.
This, of course, is a relay manufacturing problem and not a Ten Tec
design problem.
"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 believe the present
design is the optimal solution! If you drive both J1 and J2 low, then
transceiver, as designed, will not key. Basically, if it ain't broke,
don't try to fix it !
Tom - W4BQF
At Saturday 11:46 PM 12/3/2005, you wrote:
>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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> > > >TenTec at contesting.com
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> > >
> > >
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