Hi Owen

I would like to put a question regarding a previous discussion.

Not having your e-mail address, I have to catch you on another thread.

I report below what you wrote at that time:

QUOTE
From TLLC, the matched line loss in dB of LMR400 (a foam coax of similar OD to
RG213) is
3.941e-6*f^0.5
+1.031e-11*f
The first term is due to R and the second due to G.

At 144MHz, the percentage of power lost per meter due to R is
(1-10^-(3.941e-6*f^0.5)/10)*100 is 1.08%. If you do similar for G, the loss is
0.034%, so loss in R is more than 30 times loss in G
UNQUOTE

I put those formulas on a spreadsheet, but I only obtain the 0.034% figure if I
change the second formula into +1.031e-5*f (instead of +1.031e-11*f)

Any comment?

Thanks and 73

Tony I0JX
Rome-Italy

"Antonio Vernucci" wrote in
:

Hi Owen

I would like to put a question regarding a previous discussion.

Not having your e-mail address, I have to catch you on another thread.

I report below what you wrote at that time:

QUOTE
From TLLC, the matched line loss in dB of LMR400 (a foam coax of
similar OD to RG213) is
3.941e-6*f^0.5
+1.031e-11*f
The first term is due to R and the second due to G.

At 144MHz, the percentage of power lost per meter due to R is
(1-10^-(3.941e-6*f^0.5)/10)*100 is 1.08%. If you do similar for G, the
loss is 0.034%, so loss in R is more than 30 times loss in G
UNQUOTE

I put those formulas on a spreadsheet, but I only obtain the 0.034%
figure if I change the second formula into +1.031e-5*f (instead of
+1.031e-11*f)

Any comment?

Thanks and 73

Tony I0JX
Rome-Italy



Ok, firstly, there was a mistake in my formula... it is missing a pair of
parentheses, and should be (1-10^(-(3.941e-6*f^0.5)/10))*100.

That correctly finds 1.08%/m for R loss.

From my spreadsheet check, =(1-10^(-(0.00000000001031*f)/10))*100
correctly calculates 0.034%/m. Note the exponent of f is 1 in the G case.

Apologies for the parenthesis omission. I wrote down what I 'did' on an
RPN calculator rather than copying an expression that evaluated properly.

Does this answer your question?

Owen

Ok, firstly, there was a mistake in my formula... it is missing a pair of
parentheses, and should be (1-10^(-(3.941e-6*f^0.5)/10))*100.

That correctly finds 1.08%/m for R loss.

From my spreadsheet check, =(1-10^(-(0.00000000001031*f)/10))*100
correctly calculates 0.034%/m. Note the exponent of f is 1 in the G case.

Apologies for the parenthesis omission. I wrote down what I 'did' on an
RPN calculator rather than copying an expression that evaluated properly.

Does this answer your question?

Owen,

I simply pasted and copied your formulas in my Excel.

For f=144:

- the first formula gives me 0.00108893 that is 0.108%, which is 10 times lower
than your figure
- the second formula gives me 3.41851e-08 that is 0.0000034%, which is 10,000
times lower than your figure

I did that three times, same results.....

I cannot understand what can be wrong....

Tony I0JX

"Antonio Vernucci" wrote in
:

Ok, firstly, there was a mistake in my formula... it is missing a
pair of parentheses, and should be (1-10^(-(3.941e-6*f^0.5)/10))*100.

That correctly finds 1.08%/m for R loss.

From my spreadsheet check, =(1-10^(-(0.00000000001031*f)/10))*100
correctly calculates 0.034%/m. Note the exponent of f is 1 in the G
case.

Apologies for the parenthesis omission. I wrote down what I 'did' on
an RPN calculator rather than copying an expression that evaluated
properly.

Does this answer your question?

Owen,

I simply pasted and copied your formulas in my Excel.

For f=144:

- the first formula gives me 0.00108893 that is 0.108%, which is 10
times lower than your figure
- the second formula gives me 3.41851e-08 that is 0.0000034%, which is
10,000 times lower than your figure

I did that three times, same results.....

I cannot understand what can be wrong....

Tony I0JX



Ok, you have calculated for 144Hz. Try f=144e6 and don't format the cells
with %.

Owen

Ok, you have calculated for 144Hz. Try f=144e6

Yes it works fine now

Thanks for help.

Tony I0JX