[Laser] TX Circuit for high speed data.

[Chuck Hast]

On 7/1/07, James Whitfield <n5gui at cox.net> wrote:
>
> From: "Chuck Hast"
>
>
> > I have been working with the K3PGP TX circuit to run high speed data. I
> have
> > found that when my data speed goes much above 150Khz the data starts
> > getting rounded off........  Is there any problem with removing the 1K
> resistors
> > and driving the gate directly with the TTL buffered data output? ....
>
> Sorry to reply so slowly.  It took me a while to look up the schematic on
> the circuit.
>
> I suggest that you try a capacitor between the modulation input and the gate
> of the FET to restore the rounded off waveform.  Selection of value would be
> a trial and error method, but I suggest that you start with a capacitor that
> will have one tenth the reactance at the desired data rate as the resistance
> of the two 1K resistors.  It probably will not push the data rate to 10 MHz
> like bypassing the resistors completely, but should not offset the operating
> point of the circuit as much either.
>
James:
I am feeding it a square wave, and it is getting rounded off. I want to keep it
nice and square,

-- 
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."