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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