This is a real Christmass spirit with OM Ken responding so fast!
Unfortunately the only free control LPT pin with I/O capabilities is strobe
pin 1.
On the other hand, not all 8 data lines are ever used and NA makes a good
use of them in SO2R.
This is all we need to agree for LPT SO2R "Cabrillo" (apart from more
flexible M$ XP driver :-).
73 de Mario, S56A, N1YU
----- Original Message -----
From: "K1EA" <k1ea@contesting.com>
To: "'Marijan Miletic, S56A'" <artinian@siol.net>; "'Tree N6TR'"
<tree@kkn.net>; <k8cc@mediaone.net>; <TOMK5RC@aol.com>; <w5xd@writelog.com>;
<writelog@contesting.com>
Cc: <tree@kkn.net>; <S5ham@yahoogroups.com>
Sent: Sunday, December 23, 2001 8:15 PM
Subject: RE: [WriteLog] 10.69 Fixed the LPT Pin 16 Problem
> For ten years, the original design of CT used strobe (pin 1) and select
> (pin 17) more or less like a printer would: Select(pin 17) was used to
> enable keying by being set high at program startup, and Strobe(pin 1)
> did the actual keying. I think IBM dictated that strobe be high at
> startup for the same reason we like it; they didn't want the printer
> "keyed" at startup, and some printers did not pay attention to the
> select line.
>
> In the CT circuit, the base of an NPN is tied to Select through a
> resistor to provide base current and a logical enable, while the emitter
> was tied to Strobe directly to sink current from the transmitter.
>
> Sometime between January of 1996 and January of 1998, I switched the use
> of
> Select and Strobe. Strobe became the enable and Select became the keyed
> line. I think this was in response to users requesting compatibility
> with TR and the PTT enhancement. The original CW keying circuit worked
> fine for backward compatibility.
>
> As Tree and Dave have pointed out, this means strobe (pin1) has to sink
> an unknown current.
>
> One way to fix this is to use three transistors and three resistors. The
> strobe(pin1) can be buffered by using a PNP transistor in an emitter
> follower configuration. The big drawback is that emitter follower won't
> saturate. The lowest voltage the key or PTT lines would see is now a
> base-emitter drop (0.6 v) plus a collector-emitter drop (up to about .25
> v) or a total of ~0.85 v. This might not key every radio or amp.
>
> I have no tools for drawing this, but I could fax a hand drawing to
> somebody if they wanted it.
>
> As far as the other control lines go, the SO2R transmitter select line
> has moved around from time to time. Originally, CT asserted LPT2, pin 2
> (data bit 0) to select a transmitter to key.
>
> Later, but before PTT was added, the tx select line was moved to LPT pin
> 16. Later still, it was moved to pin 14 at the urging of W6NL and PA3AVV
> because TR had started using pin 16 for PTT.
>
> I would like to see standard pins for controlling the receive audio in a
> SO2R situation. Two pins are needed to select four states:
>
> 1. Radio A in left or right ear
> 2. Radio B in left or right ear
>
> This way, either radio could be sent to both ears, or in stereo mode the
> left and right ears could be swapped, depending on the physical setup of
> the radios and switching circuits.
>
> Ken, K1EA
>
> -----Original Message-----
> From: Marijan Miletic, S56A [mailto:artinian@siol.net]
> Sent: Sunday, December 23, 2001 5:30 AM
> To: Tree N6TR; k8cc@mediaone.net; TOMK5RC@aol.com; w5xd@writelog.com;
> writelog@contesting.com
> Cc: kwolff@charter.net; tree@kkn.net; S5ham@yahoogroups.com
> Subject: Re: [WriteLog] 10.69 Fixed the LPT Pin 16 Problem
>
> I am pleasantly surprised by the response of two distinguished contest
> program writers! K1EA might take a bit longer :-)
>
> My worst hamradio frustrations in 60's were with arcing power amplifiers
> at
> the beginning of CW TX. I use PTT, no annoying full BK. Sorry for few
> seconds of occasional QRM...
>
> Pin 1 might be better used for stereo/mono switching in SO2R environment
> but
> that is another question concerning M$ OS XP and NT limits to LPT
> access.
>
> I am glad this discussion takes place at Writelog reflector after a nice
> W5XD article explaining his common sense approach to program changes.
>
> MX & HNY & 73 de Mario, S56A, N1YU ( STROBE=PTT)
>
> ----- Original Message -----
> From: "Tree N6TR" <tree@kkn.net>
> To: <artinian@siol.net>; <k8cc@mediaone.net>; <TOMK5RC@aol.com>;
> <w5xd@writelog.com>; <writelog@contesting.com>
> Cc: <kwolff@charter.net>; <tree@kkn.net>
> Sent: Sunday, December 23, 2001 6:34 AM
> Subject: Re: [WriteLog] 10.69 Fixed the LPT Pin 16 Problem
>
>
> > > I always assumed that K1EA used pin 1 (strobe) for the emitter of
> the
> > > keying transistor because the state of pin 17 (CW out) is unknown
> when
> the
> > > computer is started. I'm not sure if this is a random condition or
> a
> BIOS
> > > issue, but on many computers pin 17 is high when booted which causes
> a
> CW
> > > radio to go key down (very annoying). By keeping pin 1 unasserted,
> the
> > > logging program can prevent keying until the pin 17 is low. Indeed,
> if
> I
> > > recall correctly early versions of CT keyed only pin 1.
> >
> > I had always assumed the same thing - or perhaps someone was having
> problems
> > with a leaky transistor, and this was a way to keep it off. However,
> the
> > "no CW" at power up is nice.
> >
> > > Some years later, N6TR introduces PTT control on pin 16. This pin
> has
> the
> > > same problem as pin 17 - an undetermined state at startup. To
> prevent
> > > unintentional PTT assertion at bootup, an duplicate of the CW
> keying
> > > circuit was used. However, since pin 1 has to be shared now, it
> can't
> be
> > > keyed for CW so positive keying on pin 17 is introduced.
> >
> > Yes - I think I actually "or'd" the PTT signal into the Pin 1, so that
> > you could have the same "no key" on boot feature.
> >
> > > I've always been concerned about the current handling capacity of
> the
> > > circuit connected to pin 1. This was designed as a ~STROBE signal
> to a
> > > printer, now we hang CW keying circuits and PTT on it. The CW line
> is
> > > almost certainly low current, but who knows about PTT? You never
> know -
> > > with certain radio types that line might directly pull in a relay
> coil.
> >
> > Yup - this can be a problem - and I have found some computers just
> can't
> > handle the current.
> >
> >
> > > In most of my CW interfaces now I've added a CMOS logic IC to allow
> pin
> 1
> > > to inhibit the CW keying and PTT in the signal path. The output
> devices
> > > interfacing to the radio can sink directly to ground without the
> currents
> > > going into the LPT port. One added advantage is that the key-down
> > > saturation voltage is lower, thus ensuring full power out on CW.
> (Don't
> > > laugh - I tried to use a Darlington output optocoupler to key/PTT
> one of
> my
> > > radios and it would not work!).
> >
> > I have essentially done the same thing. I just put a double inverter
> on
> > pin 1, and use that to sink the current in the emitters.
> >
> > > BTW, CW out has always been pin 17, not 16. Pin 16 is PTT. This is
> the
> > > way NA has been for years and I've just been copying everybody. I
> just
> > > checked this against a reasonably recent TRLog manual.
> >
> > Yup. I am the one who added the PTT as Dave says, and I tried to do
> it
> > in such a way that everyone else could copy it. I was trying to seel
> TR
> > Log to W3LPL once, and I guess he was impressed enough with the PTT
> concept
> > (which I think is really an important thing that most people don't
> know
> > they need) that he got Ken to add it to CT?
> >
> > > Not to embarrass anyone, but you can't count on WX0B to get the pins
> > > right. He got his NA pinouts second hand and they were incorrect
> (Jay
> told
> > > me this).
> > >
> > > Jeez...I thought we had all settled on a standard :-(
> >
> > I think we mostly have. No harm in making the STROBE go low during
> PTT in
> my
> > book.
> >
> > Tree
> >
> >
>
|