Date   : Wed, 11 Feb 2004 21:41:40 +0000
From   : Tony <kilm02@...>
Subject: Re: Teletext adapters and VHF?

On Wed, 11 Feb 2004 20:54:18 +0000, you wrote:

>L.S.
>
>Does anyone know if the Morley and/or Acorn TT adapters can be easily
>modified for VHF reception? I want to get teletext from channels on
>cable that are placed around 200MHz. The morley can be set to any value
>with the support ROM but it doesn't seem to detect anything below ca.
>450MHz (and the ATS3.10 ROM starts at a too high channel, can't seem to
>change that)
>
>Regards,
>
>Wouter

It is possible as we built a prototype multistandard version but
you'll need to replace the tuner. The Morley adapter should use a U344
which is a UHF-only tuner. If you can find something like a UV412 /418
from an OLD scrap TV (and these were used in sets made about 15-20
years ago) or any B/G/I tuner with a /256 prescaler output for the
SAB3036 and direct SAWF drive (and a datasheet) then it could be done.
The IF output is slightly out but the SAWF on the teletext adapter
might be wideband enough to cover it - if not you could use one from
the same source as the tuner.

U344 pins from the aerial end are:

1- Aerial
2-+12v
3-AGC
4-Tuning voltage
5-n/a
6-+12v
7,8- prescaler out
9-+5v for prescaler
10-IF out

Tony.