[Lowfer] 17.8 kHz TACAMO

[riese-k3djc at juno.com]

Never ever be E probed

HAR

Bob K3DJC


On Tue, 6 Mar 2012 14:39:36 -0600 "JD" <listread at lwca.org> writes:
> Even 200 feet of the skinniest coax will scarcely exhibit a couple dB 
> loss 
> below 500 kHz; coax is not the real problem below the BC band.  It's 
> the 
> impedance of the antenna not being anywhere near the input impedance 
> of the 
> radio, let alone the transmission line.  If you can tune or (better 
> yet, 
> IMO) buffer the antenna to something closer to 50 ohms at LF before 
> the 
> signal goes into the cable, you'll get much better results.
> 
> This is, after all, the secret to getting anything out of small 
> active whips 
> (I refuse to use the misnomer "e-probe").  They pick up far, far 
> less of the 
> available signal than a more typical size antenna, but because they 
> 
> transform the impedance to 50 ohms or thereabouts, they deliver more 
> of what 
> they capture to the receiver than an inherently mismatched bigger 
> antenna 
> can do by itself.
> 
> John 
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