[Elecraft] Possible doublet configuration

[Don Wilhelm]

Glen,

Yes, you can certainly do that, and it should be quite efficient.
You can bring open wire feeders or ladder line into the shack - the old 
timers did that all the time.  The greatest problem is making the 
conductive path through the wall/window or other part of the structure.  
Replacing a piece of glass with plastic is often done, or with double 
hung windows, put a plastic panel beneath the lower sash and close the 
window on it.  Don't forget to leave a drip loop at the point just 
outside, otherwise rain will drip into the dwelling.

Like any other, the feedline length will act as an impedance transformer 
(a tuner does the same thing with lumped components) - so the matching 
range required may be quite large for some feedline lengths.  The 
switchable balun may help with that, but try to stay away from feedline 
lengths that produce a very low  or very high impedances in the shack 
because the balun can become ineffective at impedances far removed from 
its nominal 50 ohm or 200 ohm design points.

I will not give any specific antenna lengths and feedline lengths, but 
you can experiment with either the real antenna or do some work with the 
TLW software (download from ARRL website) to tell you what lengths will 
work for you.

73,
Don W3FPR

Glen Torr wrote:
> Hello All,
>
> Following this thread with much interest. I need a stealth antena and
> a doublet may do the job.
> Could I feed my K3/100 with ATU into a BL2 right at the antenna
> connector, the output of the BL2
> to home made ladder line, (2 to 4 inch spacing) to a doublet approx
> 1/2 wavelength on the lowest
> freq?
>
> Is it OK to bring ladder line into the shack?
>
> The 1:1 or 4:1 of the BL2 might provide matching options in difficult cases.
>
> Thanks for any thoughts,
>
> Glen VK1FB
>   
>