Hi Roger yes you are right of course its the drift within a qso period or even an over that is most important. Very Good.

I wonder whether the use of 10MHz as an "IF" would be a possibility? This would allow readily available TCXOs or even OCXOs to be used for the LO. I guess the split should be enough to allow your filter/diplexor to work. It obviously only removes one source of drift, one cant do much about the 817, but that also should be less at 10MHz?

Alan G3NYK

--- On Wed, 9/12/09, Roger Lapthorn <[email protected]> wrote:

> From: Roger Lapthorn <[email protected]>
> Subject: Re: LF: 500kHz simple 5W TX/RX transverter >>DATA MODES<<

> To: [email protected]

> Date: Wednesday, 9 December, 2009, 23:27

> With the transverter "in the
> open" (rat's nest) on the desktop there is a
> warm-up drift of about 40Hz HF until things settle down.
> This has not been an issue with WSPR as the drift in a
> single TX slot is only about 1-2Hz usually (WSPR copes with
> this) and it soon settles down to 0Hz drift. I have not
> tried QRSS but imagine you'd have to ensure the xtal
> oscillator is made more thermally stable for v.slow QRSS,
> but would guess it would be OK for some moderate QRSS
> operation. Putting the whole unit in a box should help.
>
>
> My little circuit works, but is surely capable of much
> improvement, HI.
>
> 73s
> Roger G3XBM
>
> 2009/12/9 ALAN MELIA <[email protected]>
>
> Sounds good Roger and Graham...
> what it the stability like the problem with
> transverters/upconverters normally is that while ok for some
> modes they are  often not stable enough for the very weak
> signal modes. These are modes where you need to know the
> frequency of a station very accurately because you will not
> hear it, or it will only pop above the noise for short
> periods.
>
>
>
>
> Alan G3NYK
>
>
>
>
>
> --- On Wed, 9/12/09, Graham <[email protected]>
> wrote:
>
>
>
> > From: Graham <[email protected]>
>
> > Subject: LF: 500kHz simple 5W TX/RX transverter
> >>DATA MODES<<
>
> > To: [email protected]
>
> > Date: Wednesday, 9 December, 2009, 22:13
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > All
>
> >
>
> > This  latest
>
> > addition to  the
>
> > HF / MF  tx convertor  opens the  door
>
> > to  data
>
> > communications  on 500 ... ranging  from
>
> > 'all'  the K1JT systems
>
> > through to  the  single carrier
>
> > multi  tone
>
> > systems  of
>
> > MFSK  ,  DOMINO and THOR  .. even
>
> > the  almost
>
> > forgotten  Amtor-arq  and Packtor modes , anyone
>
> > still  have
>
> > there pk232
>
> >
>
> > listed  are
>
> > data  modes that  may be  used with
>
> > non-linear systems :-
>
> >
>
> >
>
> > http://groups.google.com/group/uk500khz/web/meat-grinder-comms
>
> >
>
> > G..
>
> >
>
> >
>
> >
>
> >
>
> > From: Roger
>
> > Lapthorn
>
> > Sent: Tuesday, December 08, 2009 12:20 AM
>
> > To: [email protected]
>
> >
>
> >
>
> > Subject: LF: 500kHz simple 5W TX/RX
>
> > transverter
>
> >
>
> > Dear All,
>
> >
>
> > My WSPR tx up-converter has now been modified to
>
> > a full TX/RX tranverter suitable for WSPR, QRSS and
>
> > CW  in a
>
> > very simple way, making use of the FT817 split
>
> > facility which allows you
>
> > to RX on 500kHz and TX on 28MHz. By adding a series
> LC
>
> > between the TX PA and the
>
> > FT817 input/output RF connection (with back-to-back
> diodes
>
> > at the L and C
>
> > junction, this allows "pass through" from
> the
>
> > 500kHz ATU to the FT817 on RX
>
> > (tuned to 500kHz). On TX, the diodes conduct and the C
> part
>
> > is in parallel with
>
> > the first cap in the TX low pass filter. This scheme
> is now
>
> > working really well
>
> > with good RX sensitivity and no change in TX power
> out.
>
> >
>
> > Schematic of the
>
> > transverter is on my blog at http://g3xbm-qrp.blogspot.com/
>
> > . My
>
> > attempt to add it as an attachment to an email here
> earlier
>
> > failed.
>
> >
>
> > This more or less concludes my 500kHz experimenting,
> apart
>
> > from
>
> > getting a few more CW QSOs in the log. It's been
> great
>
> > fun all the way with lots
>
> > of support from folks here. I was going to try 136kHz,
> but
>
> > think I will now give
>
> > this a miss for now.
>
> >
>
> > 73s
>
> > Roger G3XBM
>
> > --
>
> >
>
> >
> -------------------------------------------------------------
>
> > http://g3xbm-qrp.blogspot.com/
>
> > http://www.g3xbm.co.uk
>
> > G3XBM
>
> >  GQRP 1678      ISWL G11088
>
> >
>
> >
>
> >
>
> >
>
> >
>
>
>
>
>
>
> --
> -------------------------------------------------------------
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
>
> G3XBM    GQRP 1678      ISWL G11088
>
>