Topband: To clamp or NOT...that IS the question

[Petr Ourednik]

Hello Jim,

3x fast relays, 2x switching transistors, 3x resistors and box with
connectors...
You have KD9SV front-end saver. No diodes, no RX performance
degradation.
I never had issue on my K3 with KD9SV saver in ext.RX front-end.
Let me know I will send You the drawing.

Hope it helps my friend,
best regards,

73 - Petr, OK1RP
http://160mband.blogspot.com

On Fri, Jan 17, 2014, at 06:37 PM, James Rodenkirch wrote:
> 
> 
> 
> A friend of mine is building me a switching arrangement with a reed relay
> to switch between my transmit antenna and a receive delta loop to the one
> antenna input for my Ten Tec Jupiter (I operate at QRP levels for
> contests).
> As an added measure of protection for the KD9SV low noise pre-amp I use
> with my 160/80 delta loop antenna, he believes clamping the RX antenna
> port or shunting to ground during TX sounds like a nice thing.  But, he's
> seen arguments that clamping receiver input with diodes degrades the
> receiver performance. He find this believable, but I don't know how true
> it is, e.g., he knows KD1JV claims his RX performance is achieved by
> using 2N7000 FETs to do T/X switching.
> He has a bunch of 2N7000 and will probably use one to turn on the relay. 
> He can turn on another one along with the relay driver that will shunt
> the RX antenna port to ground but he wonders if that would degrade
> receiver performance.
> Thoughts?  72/72, Jim Rodenkirch K9JWV
> 
>  		 	   		  
> _________________
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