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[ct-user] LPT Keying Cable? Problem

To: <ct-user@contesting.com>
Subject: [ct-user] LPT Keying Cable? Problem
From: John" <nfn06110@naples.net (John)
Date: Fri, 4 Aug 2000 14:35:38 -0400
Why not just plug a straight key into the rig or have you all forgotten
what they are!!!!!!!!!

As a flunky ex tech plus even I remember what a straight key does and
how to work it!

Also that is the reason we dumped CT and all bought WriteLog which works
great.

73 and maybe you will "upgrade" someday too!

WA3TIH


----- Original Message -----
From: <k2qmf@juno.com>
To: <ludal@dmv.com>
Cc: <ct-user@contesting.com>; <n5nj@gte.net>
Sent: Friday, August 04, 2000 2:09 PM
Subject: Re: [ct-user] LPT Keying Cable? Problem


>
>
> I would also like to find out just what was the fix!!
>
> 73,  Ted  K2QMF
>
> On Fri, 4 Aug 2000 09:48:08 -0400 "Dallas Carter" <ludal@dmv.com>
writes:
> >
> >
> >> I missed it.
> >>
> >> What is the solution ?
> >>
> >> What was positive - what was negative ??
> >>
> >> After all of this, please share the details.
> >>
> >> Robert E. Naumann
> >> N5NJ / V26O
> >
> >I have seen several requests for a repeat of the suggestions that I
> >provided
> >with regard to Franks keying problem.  Hope this reprint of the
> >message to
> >him sheds some light on the solution.  W3PP...
> >
> >Frank, I think I have read most of the responses to your query, and
> >your
> >responses to them.  I take it you are still in a quandry as to what
> >the
> >problem is.  I am not the worlds best theorist, and usually just
apply
> >emperical solutions, so forgive me if I am not theoretically pure in
> >my
> >comments.
> >It would seem to me that first you  must determine whether the
problem
> >lies
> >in the s/w, computer, interface or the radio.  Here is the process
> >that I
> >would adopt, then I will provide, what I believe is background,
> >explaining
> >some relativily common problems.
> >
> >    Unplug the keying interface from the radio.  With an ohm meter on
> >the x1
> >ohms scale, connect one lead to the keyed element (ring or tip) and
> >the
> >other to the sleeve of the phone plug.  Send a message and note if
the
> >meter
> >moves to the rythm of morse.  You may have to reverse the leads.
> >            If the meter is moving, you know that the s/w and
computer
> >are
> >ok, and that the interface is doing something.  You have obviously
> >checked
> >to see that shorting these two points together while connected to the
> >radio,
> >keys the radio.  If so, then it is the interface that, while working,
> >is not
> >sufficient to key your radio.  I will explain this later.
> >
> >    If the meter is not moving, put the meter on a low voltage, ie
> >10vdc
> >scale, and put the black lead on the emitter lead of the transistor
in
> >the
> >interface, and the red lead on the computer side of the base
resistor.
> > Send
> >another message and check to see if the meter reads the keying
> >voltage.  If
> >it is, then you have again confirmed that the s/w and computer are
ok.
> > If
> >not, then you need to check out that computer & s/w.
> >
> >    In both cases above, if the meter is responding, the problem lies
> >between the computer and the radio, or, the interface.  As I recall,
> >the
> >interface is an NPN transistor with a base resistor of 1K or so that
> >is
> >connected to an LPT pin (the keying source).  The emitter is
grounded,
> >and
> >the collector is connected to the radio key line.  The base resistor
> >limits
> >base current so that you dont burn up the transistor, and as the
> >voltage on
> >the base goes positive, the transistor turns on, shorting the
> >collecter to
> >ground, keying the rig.  Collector voltage (VCC) is provided by the
> >rig, and
> >is normally plus 12 vdc.  Here is the point...   If the Beta (gain)
of
> >the
> >transistor is low, and the base resistor is too high, there will not
> >be
> >enough base current to turn on the transistor.  This may also be a
> >function
> >of the radio limiting the collector current and/or voltage.  If this
> >is what
> >you are seeing, lower the value of the base resistor and see if that
> >corrects the problem, else try a different transistor.
> >
> >    I have eight interfaces that I use here.  Some of them will key
my
> >FT-1000MP's but not all of my TS-940's.  One in particular would not
> >key a
> >guest ops 940, and for the contest I just swapped it out with the
> >cable from
> >one of my 940's.  I ultimately got it to work on his rig by changing
> >the
> >base resistor.  His 940 keying circuit aparently takes more keying
> >current
> >than my other rigs.  One more thing.  If you dont see the voltage at
> >the LPT
> >pin, first suspect that the transistor base is not grounded.  It may
> >be that
> >the computers lpt port is not wired like most.  Should be easy to
> >check that
> >and find a ground source.  This is by no means a complete trouble
> >shooting
> >effort that I have outlined for you, but I hope it gives you some
> >ideas.
> >
> >    very 73,
> >Dallas  W3PP
> >
> >
> >
> >--
> >WWW:                      http://www.k1ea.com/
> >Submissions:              ct-user@contesting.com
> >Administrative requests:  ct-user-REQUEST@contesting.com
> >Problems:                 owner-ct-user@contesting.com
> >
>
> ________________________________________________________________
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> --
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>
>


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