On Fri, 04 Feb 2005 13:46:50 -0500, Spam Fighter wrote:

I am looking for a .xls spreadsheet (or something that works under
LINUX), to calculate the equations for matching common maritime mobile
HF whip antennas:

8 ft
10 ft
15 ft
23 ft
40 ft (backstay, approx 5/8 on 20 Meters)

I want to calculate the matching parameters including voltages generated
in the tuner for the 1.8 3.5 7 10.1 14 21 28 MHz ham bands and the 2 4 6
8 12 16 and 22 MHz marine bands.

The ARRL ANTENNA HANDBOOK, 18th edition, chapter 18, has some equations
and a table of calculated values for a 8 ft whip on ham bands. I wish
to duplicate the calculations and figure out the voltage maximums for
component values for, say, 100 W key down power.

Take for example the 1st row of the table:

BASE LOADED 8ft whip
F=1.8 MHz
Loading L = 345 uH
Rc Q=50 = 77 ohms
Rc Q=300 = 13 ohms
Rr =0.1 ohms
Feed R = 23 ohms
Matching L = 3 uH

Now at 1.8 MHz
XL of 345 uH = +j3902 ohms

Do I calculate the current from P=I*I*R so for Rr = 0.1 ohms, I =
sqrt(100/Rr) = 31.6 A so V XL is I*R = 31.6*3902 = over 123 KV? (seems
excessive)

or do I use the R values of 77, 13, or 23 ohms? (4.4 KV, 57 KV, 8.1 KV
)?

Do I multiple all RMS voltages by sqrt(2) to convert RMS to PEAK?

Greg
VE0ACR
gblair _at_ sympatico _dot_ ca

I have it all sorted out. The 2002 ARRL Handbook has a similar
table complete with voltages. However, there was a mistake in the
text. Working backwards from the stated result, we found the text used a
coil capacitance value of 2.5 pF while stating they we using 2 pF. They
also assume Rg (ground) is zero. I can duplicate their table and have
calculated the data I was after for the other whip lengths.

I have a .xls spreadsheet I can email anyone who is interested.

Greg Blair
ve0acr _at_ rac _dot_ ca