Coaxial dB Loss

[W0AJA]

I picked up 2 new rolls of LMR-400 solid center for a good price, factory installed PL-259's.

When I roll the m out on the ground, I get a straight 1.4 dB loss on 146.000

However when I send it up the pole or in the tree I get about 7-11dB of loss. Factory has no idea, and I figure I would ask the only nice group for some elmering. Am I missing some thing with coax?

W3WN: Ron, I can hit the 146.640 and the 147.090 now but wish the loss was lower, doesn't make real sense.

Feel free to ask your questions to help answer my question!

Thanks!

[PA5COR]

Some questions arise, length of coax?
How did you measure loss on the ground and when the coax was up to the tower?

[N2CHX]

Some questions arise, length of coax?
How did you measure loss on the ground and when the coax was up to the tower?

Yup, this is the first question I have. What method did you use for arriving at the numbers?

[W0AJA]

1.) 100 Feet (Solid Core)
2.) I have a MFJ 259C and it was in the settings to measure coax loss.

[K7SGJ]

Are you measuring the coax terminated (or shorted), or open at the end? If you are measuring it unterminated, put a 50 ohm resistor or dummy load on the end it, and measure again and see if it changes radically.

ETA I heard of several people having weird readings using the coax loss function on the 259B. It appears to be very erratic over small frequency excursions. However, that was with the B series, which is what I have. I'm not familiar with the C series as I've never used it.

[W0AJA]

Yes, it was unterminated, just a PL-259 on it, no dummy load or antenna.

But when it goes vertical it is connected to a antenna.

[K7SGJ]

Yes, it was unterminated, just a PL-259 on it, no dummy load or antenna.

But when it goes vertical it is connected to a antenna.

Let me see if I have this right, you're reading it when it is vertical AND hooked up to the antenna? Or is the coax just supported vertically and open at the end when you measure it?

[N2CHX]

So when measuring on the ground you leave it open and unconnected, but when measuring it in the air you have the antenna connected to it?

[W0AJA]

Yes?....

Well, now that I think about it you would get a higher coaxial loss because of the antenna element and radials. I just thought of that now that I re-read these bottom 2. So, to get a true loss measurement, it should be unterminated or terminated with a dummy load. Correct?

I haven't played much with coax measurements and im just getting my feet wet.

[W2NAP]

LMR-400 about 1.4 loss per 100 @ 146.

ignore the connected to the antenna..