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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

73 and maybe you will "upgrade" someday too!


----- 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>
> >
> >
> >> 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
> >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
> >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
> >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
> >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
> >the
> >interface, and the red lead on the computer side of the base
> > 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
> > 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
> >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)
> >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
> >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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