[Lf] [Fwd: LF: beacon power control]

[Andre' Kesteloot]

Rik Strobbe wrote:

> Hello André,
>
> Apart from having the different powerlevels Marco has als the problem that
> he has to retune his antenna when the WX changes. This is a problem when he
> is running an unattended beacon. Therfore I suggested to have some feedback
> from the amp-meter (antennacurrent) in order to have always antennacurrent
> (= same ERP) at the different powerlevels, independent from WX.
> Meanwhile I received mails from 2 other OM that are interested to install
> low-power beacons, so it might be a good idea to develope a beacon
> providing constant ERP (indepent from antenna detuning) levels.
> Any interest for this project in the US ?
>
> 73, Rik ON7YD
>
> At 08:17 3/05/00 -0400, you wrote:
> >Rik Strobbe wrote:
> >
> >> [...]
> >> As the beacon is meant to be low-power (10mW and less) a relative small TX
> >> power can be used (50 Watts and less), so it can easily be overdimensioned
> >> to provide extra safety.
> >
> >Maplin has a small class A amplifier using a LM 1875 that easily puts out 25
> >watts at 136 Khz. It is stable, has automatic current limiting and
> overheating
> >protection
> >Because it operates in class A, the output can  be controlled simply by a
> step
> >attenuator at the  _input_   of the amplifier.
> >>Just a thought
> >>73
> >Andre' N4ICK