Re: LF: 500kHz simple 5W TX/RX transverter >>DATA MODES<<

[Roger Lapthorn <rogerlapthorn@gmail.com>]

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 <alan.melia@btinternet.com>

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 <g8fzk@g8fzk.fsnet.co.uk> wrote:

> From: Graham <g8fzk@g8fzk.fsnet.co.uk>
> Subject: LF: 500kHz simple 5W TX/RX transverter >>DATA MODES<<

> To: rsgb_lf_group@blacksheep.org

> 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: rsgb_lf_group@blacksheep.org
>
>
> 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