[Lowfer] Re: New antenna

Mon, 21 Jan 2002 22:26:17 -0500

Ed,

I tried a couple of the low current versions. I think a VN88 and a VN10.
 I am away from my notes on this aspect.)  The intermod performance was
worse than the Burhans J310 design at lower voltage and current.  The gate
capacitance was somewhat higher so the overall sensitivity suffered,  It was
a bad tradeoff.

Also, those low current VMOS devices are about out of production and I could
only find them from NOS stocks but if they had been really great I suspect
we could have found a reliable source.  Since RF performance is not
controlled on these devices designed as relay drivers, we might have found
some makers that made good devices and some that were rotten.

The CP666 seems to give both low gate capacitance and great intermod
performance, that is why it is so unique.  The intermod performance is
speced and controlled by the maker.  Note also the superb noise figure at
VHF for this device.  I hope this will translate to LF but am still working
on measuring noise figure at LF so nothing specific is available yet.

Frank K0BRA

-----Original Message-----
From: Ed Phillips <[email protected]>
To: [email protected] <[email protected]>
Date: Monday, January 21, 2002 9:01 PM
Subject: Re: [Lowfer] Re: New antenna

Snip snip

Wonder if anyone has experimented with using some of the power VMOS or
IRC Hexfets?  Many years ago Bill Oxner (?) from Siliconix gave a talk
at Hughes in which he recommended their VMOS for really wide
dynamic-range applications.  Used POWER devices as RF amplifiers and
active mixers.

Ed
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