[RTTY] FSK interface circuit troubles

[k0bx at arrl.net]

The kenwood TS-940 uses a reverse FSK from everyone else.
In my TS-850 there was a menu setting to reverse the FSK.  I am not sure of the TS-940 but I think it had it.

There is some writeups on FSK and Kenwood on my webpage at:

http://www.qsl.net/k0bx   This is for the TS-850 but applies to most Kenwood.

Joe K0BX

Stop the insanity!
Please do not add me to any distribution lists (Joke, Stories or Junk) without my permission.


--- On Wed, 12/10/08, Alfred Frugoli <ke1fo at arrl.net> wrote:

> From: Alfred Frugoli <ke1fo at arrl.net>
> Subject: Re: [RTTY] FSK interface circuit troubles
> To: rtty at contesting.com
> Date: Wednesday, December 10, 2008, 6:19 AM
> The one thing I didn't mention is that I'm running a
> KW TS-940, this seems
> to be a detail of interest in all the replies I've
> gotten.
> 
> 
> 73 de Al, KE1FO
> 
> -----
> Visit my amateur radio contesting blog at
> ke1fo.wordpress.com.
> 
> 
> On Tue, Dec 9, 2008 at 10:16 PM, Alfred Frugoli
> <ke1fo at arrl.net> wrote:
> 
> > Hello folks,
> >
> > I'm trying to build up the interface listed at the
> bottom of
> >
> http://www.aa5au.com/rttyinterface.html#PNP_Transistor_FSK_Circuit
> using a
> > PNP transistor.  I'm using generic PNP transistors
> from Radio Shack (the
> > package says they're 2n3906 but there are a mix of
> various numbers in the
> > package) and a 1k resistor.
> >
> > I'm building up the circuit for use with Software
> FSK in Writelog (using
> > RTTYwrite not MMTTY).  I originally built the NPN
> circuit at the top of the
> > page and got inverted keying.  Then I built up the PNP
> circuit and all was
> > well.  I then went to build up a 2nd identical
> interface, and it did not
> > work.  I took apart the case of the first interface to
> make sure they were
> > wired identically.  I put it in line without the case
> to make sure it
> > worked, and it did not.  Since that point I have not
> been able to build a
> > working interface, and the original that did work, no
> longer does.
> >
> > I have tested the RTTY port on the rig, and all is
> well there - when I
> > ground the center pin it shifts tones.  I've
> tested the Serial port, and I
> > get either +9v or -9vdc between pin 3 and signal
> ground depening on the
> > state of the serial port.  I've tried a different
> USB/Serial converter, and
> > no joy there, so I'm assuming I've done
> something wrong in the circuit.
> > I've tested my transistors prior to inserting them
> in the circuit and they
> > seem to be good both before being in the circuit and
> after not working (i.e.
> > nothing is zapping them when they get connected to the
> rig and serial
> > port).  I've "reversed" the transistor
> (i.e. swapping emitter and collector
> > leads just in case the transistor is
> miswired/mislabeled).  I've tried
> > connecting the base back to the "ground"
> connection of the RTTY port on the
> > rig rather than to pin 5 of the serial port (signal
> ground).
> >
> > Everything I've tried has resulted in the rig not
> shifting tones.  The
> > USB/Serial converter has an LED to show activity, and
> when I send I can see
> > activity on the prort, but the rig just stays on a
> single tone and does not
> > shift at all.
> >
> > I don't know what else to try, except maybe a
> lower value resistor, but
> > that doesn't seem to make sense since the circuit
> worked once.
> >
> > Thoughts?
> >
> > 73 de Al, KE1FO
> >
> > -----
> > Visit my amateur radio contesting blog at
> ke1fo.wordpress.com.
> >
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