Re: LF: Noise cancelling by using optic transmission of RX signals

[Dexter McIntyre W4DEX <dmcintyre@att.net>]

James Moritz wrote:

> I think the role of the ground with active whips is often neglected - 
> the output of the whip preamp is the voltage differential between the 
> whip element and the circuit ground, so the ground connection is just as 
> much part of the antenna as the whip element itself is. Clearly, an 
> electrically quiet ground is needed for the active whip, whether this is 
> provided by the coax feeder or a separate local ground connection.
Years ago I built a simple MPF-102 active whip into a gutted VHF coil enclosure 
of a NMO mobile antenna.  I quickly noticed the antenna performed much better 
when mounted on a vehicle roof than when mounted on a mast.  Even when the whip 
was elevated up to 10 meters above the vehicle the roof mount received much better.
As for the optical link, I attempted to link a remote VLF-3 by IR back to the 
shack.  I never got that to work very well but I feel sure someone that knows 
what they are doing could perfect it.
Dex