Topband: BCB Filter (related to Antenna Analyzer question)

[Rick Karlquist]

Michael St. Angelo wrote:
> Rick,
>
> 900 feet? What type of coax are you using?

Open wire line, 4 AWG aluminum, 450 ohms.  A few .1 dB's
of loss on 160.

>
> You could probably cancel out the coax by using a VNA like the AIM4170 of
> N2PKVNA and performing a OSL calibration at the antenna end. You would get
> lots of exercise walking back forth to to switch between the open, short,
> 50ohm and actual load!

Yes, the AIM4170 can calibrate out both the 160 meter BCB filter and
the open wire line, including baluns at each end and residual coax.
It is tedious and slow and not perfect, but it does work.  I have
350 feet of RG218 going to my MonstIR, and I tried to calibrate that
out with the AIM4170.  It sort of worked, but there were ripples in
the response.

And yes, I do get a lot of exercise doing the calibration.  I recently
acquired a lap top so I can locate the AIM4170 out at the antenna.
I had quite a bit of trouble getting the USB to serial port adapter
to work with the AIM4170, but eventually got a special driver file
that worked on my lap top at least.

Rick N6RK