[Elecraft] how did I calculate the loss?

[George, W5YR]

Dave, I missed the part where the ladderline and 600-ohm line have to be 270
ft long and the coax only 180 ft.

Could you either repeat that part or attach a copy of your email?

I might mention that TLDetails is also an excellent program for handling
problems of this type. Google will find it for you.

73, George W5YR
w5yr@att.net


----- Original Message ----- 
From: <drcuthbert@micron.com>
To: <elecraft@mailman.qth.net>
Sent: Monday, December 15, 2003 4:05 PM
Subject: [Elecraft] how did I calculate the loss?


You might be wondering how I calculated the line loss with the mismatched
load. I used two methods. NEC (with a physical T-line) and with WinSmith.
But, I remembered a link to an online program that easily solves this type
of problem. Here is the link: http://fermi.la.asu.edu/w9cf/tran/

Let's solve the 30 -j500 ohm load with 180 feet of RG213:
Loss = 9.7 dB
Let's solve the 30 -j500 ohm load with 270 feet of 450 ohm ladder ohm line:
Loss = 2.8 dB
Let's solve the 30 -j500 ohm load with 270 feet of 600 ohm opn line:
Loss = 0.9 dB

Not that bad with 600 ohm line. Less line length means less loss (it's not
linear though). And with 600 ohm line we don't have to avoid any line
lengths to avoid an awkward impedance at the K2, as we might have to with 50
ohm line. For example, a 45 degree, 600 ohm line (68 feet) gives 10 +j50 at
the K2 and only 0.42 dB of line line. I am now of the opinion that feeding
the 8030 with open line, and tuning with the K2, is a viable option.

    Dave WX7G