>
> You can use L as shunt to ground to allow static bleed off.
This is absolutely my choice whenever I can use it...possibly first and
foremost because it's nearly free.
You just need one more little homemade coil of wire, you tweak the coil tap
on the big inductor in series with the antenna element to get your resonant
frequency, and tweak the shunt coil to get 50 ohms.
No special components or cores required. Of course, in the case of a base
loaded 18m tall vertical, one coil tap just doesn't get you much frequency
agility.
But, if you set up the L-network to give you a perfect match at 1850 or so
you can probably go 1800-1900 using a shack tuner without too much loss...
I actually ran the numbers for a network set up at 1830 and found that at
1800 you actually have LESS LOSS in 50 feet of RG-8/X with the mismatch than
with a perfect match (0.110 dB to the matched loss of nearly 0.2dB). No
kidding. It's a rare quirk, but it can happen. Of course, the resulting
3:1 SWR doesn't make your rig happy, so you have to kick in the tuner with a
little bit of loss.
At 1.9MHz the line loss rises from 0.2dB to 0.9dB and the impedance is
probably a little harder to match, but it can be done.
So you might consider that as an easy option that just requires you to wind
a couple coils (and starting point values, both in microhenries and in
physical dimensions are available on my website)
73,
Dan
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