[Laser] Retro-Reflector test

[Chuck Hast]

On 5/12/07, Jens-Peter Gärtner <lev1985 at web.de> wrote:
>  >Wouldn't a high frequency fm-modulated carrier solve the problem? It
> >> >also would give you more flexibility. Perhaps you would like to
> >> >transmitt some tv-signals later...
> >>
> >> No! Using an FM modulation scheme means your detector has to be
> >> dumbed down so that it admits the carrier frequency plus the width of
> >> the modulating signal (sidebands). The NEP varies (is reduced) by the
> >> square of the overall bandwidth-very bad!
> That's a point I didn't thought about yet.
>
> How do your keying-amplifiers look like?
>

At the speeds I am using out of a TNC (38k4-128kb) I am using a VN-10
MOSFET. It switches the 5mw diodes just fine. Average switching times
are ON = 7ns, OFF = 9ns. Vds=60v, Id=.21 to .27 amps continuous (there
are various packages, so that is why there are various current ratings) Id
pulsed = 1 amp.

As you can see this transistor will switch currents well up to where I will
be working, so I do not look at having to replace it until I start moving up
to really high signaling speeds.



-- 
Chuck Hast  -- KP4DJT --
To paraphrase my flight instructor;
"the only dumb question is the one you DID NOT ask resulting in my going
out and having to identify your bits and pieces in the midst of torn
and twisted metal."