[linux-dvb] Re: 13/18V voltage with DVB-S 1.6 (Grundig 29504-491)

["Dr. Werner Fink" <werner@suse.de>]

On Tue, Jun 01, 2004 at 10:55:24AM +0200, Johannes Stezenbach wrote:
> Dr. Werner Fink wrote:
> > 
> >      this card in the subject does have sometimes problems
> > with horizontal transponder, especially with the that of
> > ZDF and KiKa.  It seems that the voltage may be to less
> > (< 18V).  If I use a so called inline amplifier the no
> > of the horizontal transponders are visible whereas the
> > vertical are really perfect and very fast switched.
> 
> What good can such an inline amplifier do? It will only add noise.
> I don't know much about the Grundig FE, but probably you
> should check your cables and LNB?

Already done: All F connectors are clean and dry. The cable
is high shielded one and a so caled 100dB coax.  Beside this
there are no shorts between the shield and the conductor.
The LNB works perfectly with a normal receiver. Only the
window cross cable reduce the signal strengh about 3dB
and slightly increase the noise.  This was the reason for
me to give the inline amplifier a try directly behind the
LNB out connector ... and it really increase signal strengh
and the noise is not measurable changed ... but only on the
vertical transponders.  The horizontal are simply lost with
this amplifier. I guess that the power for the amplifier
(got from the receiver in this case from the DVB card)
reduce the power for the LNB and it drops under the
required switching voltage.

Without amplifier it depends on the weather ... if the
weather is fine, the signal of the ZDF transponder
(11954 MHz horizontal on Astra S19.2E) is good enough but
with some rain or heavy clouds the signal is worse short
after switching on to this transponder, some seconds after
switching on the signal gets better.  Heavy rain kills
the signal on this transponder, and other horizontal go
also worse but stay mostly visible.

> > Is there something like a phantom powering available to
> > help the DVB-S cards with their weak powering.  Or should
> > I use a multi-switch for this single LNB/LNC flat dish?
> > 
> > Maybe the register 0x20 could get an other value than
> > 0x11 (first and fifth bit) within tda8083_set_voltage()
> > to get 18.5V instead of 18V ... if this is possible
> > with the Grundig tuner.
> 
> I have no idea, because I don't have a data sheet for the
> NIM. TDA8083 register 0x20 only defines four of the six
> general pupose i/o pins, it depends on the NIM what is
> connected to them.




         Werner