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From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <290328.96637.qm@web25405.mail.ukl.yahoo.com> <007901c7cab3$6071b590$0b646a58@wgt01>
Date: Fri, 20 Jul 2007 11:21:46 +0100
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Subject: Re: LF: 500 RTTY first 2 way
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Status: O

Hi Gary I was thinking you might do as well to use the old Hamcom for
transmit, but of course you have the same problem switching programs though
you should be able to run two windows as Hamcom doesnt use the sound card. I
had wondered about RTTY having been an old adherent, indoctrinated
originally by Brian in the late 1960s !! I ran a non-linear PA on 70cms
quite successfully, and my synth get will easily generate proper FSK. All
that was with real mechanical decoders though !!

Cheers de Alan G3NYK

----- Original Message -----
From: Gary - G4WGT <g4wgt@tiscali.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: 20 July 2007 10:50
Subject: Re: LF: 500 RTTY first 2 way


> Hi Brian, LF,
>
> Thanks for your mail Brian.
>
> I have previously received Graham's several transmissions using PSK but as
> that required a linear Tx I was unable to reply, Graham pointed out to me
> that the RTTY program MMTTY featured a setting for FSK output via the COM
> port which would anable me to drive my DDS VFO using the CW offset as I do
> for DFCW & the G0MRF class D Tx.
>
>  I looked at the possiblity & found that I only required to modify my
> QRSS/DFCW interface by switching the FSK drive from DTR to TxD so I fitted
a
> switch to allow both modes when required. That worked fine but I had to be
> able to Tx & Rx narrow shift. The prog MMTTY allowed me to Tx down to
> whatever shift I set in the DDS VFO offset so I tried the preset 23 Hz
shift
> but found I could not Rx very narrow shifts with MMTTY. I downloaded
MixW218
> & that produced 100% copy down to 30 Hz shift so I set that as my
standard,
> Tx with MMTTY & Rx with MixW218 but it was hard work swapping programs for
> Tx/Rx.
>
> Graham used MMTTY  prog at 25 Hz shift frequency  503.6 KHz using a audio
> feed (AFSK) to the MA1723 exciter (I think that is RACAL) followed by a
> linear amp. I think that if Graham could bring his shift up to 30 Hz I may
> get a more solid copy.
>
> The MixW218 will not do the COM FSK drive like the MMTTY so I must try to
> use MMTTY for both Rx & Tx if I can get the profile right or maybe go for
a
> linear Tx design.
>
> I hope that helps.
>
> 73
>
> Gary - G4WGT - IO83qp
>
> ----- Original Message -----
> From: "brian hodgson" <g3ykb@yahoo.co.uk>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Thursday, July 19, 2007 10:47 PM
> Subject: Re: LF: 500 RTTY first 2 way
>
>
> > Hi Gary & Graham -
> >
> >  Congratualtions on the 500 kHz RTTY QSO.
> >
> >  I once tried to stir up interest in RTTY on 136 KHz but got no takers.
> >
> >  I've used PSK on 136 but that needs linear amps and not many LF ops
have
> > such kit.
> >  However, almost any transmitter can be used for FSK RTTY. I'd be most
> > interested to hear how you produce the FSK signal.
> >
> >  Regards - Brian
>
>