From: Gerhard Hickl <gerhard.hickl@aon.at>
To: rsgb_lf_group@blacksheep.org
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Date: Thu, 23 Sep 2010 06:41:27 +0200
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Subject: Re: LF: PA0RDT miniwhip in TX?
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Marco !

The 100nF is just to remove DC from the pad (6V)....
I wonder if static cracks will induce enough voltage to clamp the diodes
but I will find out as Roelof said in his post.

Roelof !

It's not only about the costs it's also to avoid the work one has to
repair the antenna.

73 es gl

OE3GHB
Gerhard



Am Mittwoch, den 22.09.2010, 22:34 +0200 schrieb Marco IK1ODO:
> Hello Gerhard,
> 
> the 100n capacitor will do nothing, it is in series with the input 
> pad capacitance (a few pF).
> The diodes will clamp at 0.6 V, that is too low (every static "crack" 
> will send the diodes in conduction) and limits the dynamic range.
> More, they will add capacity (2 pF each?) at the very critical point 
> of the amplifier input, decreasing the gain.
> I think I will leave the gate alone, as in the original design.
> 
> Possibly the idea of a small reed relay to be closed in TX may be 
> better; those have very low C. But I will do that only after the 
> ninth burnt J310 - they are so cheap from Roelof :-) (just jocking, 
> of course, I could not resist)
> 
> 73 - Marco IK1ODO
> 
>