Using a MFJ antenna analyzer

[Wyandotte]

So I put up a 2 meter antenna on the house. Used Belden 9913 coax. I hook up the MFJ 259B analyzer, says the match is a beautiful thing. But also says I have 5.8 dB loss in the coax.

I'm sure folks here have used the MFJ, is this thing saying that I'm losing half my signal in the coax? Is the "loss in the coax" reading an accurate reading? If I remember right, 6dB is double the signal, so a 6dB loss is half the signal. (I think).

It's only about a 30' run, if that. I'm full copy on machines 50 miles away.

[N_Jay]

In power 6, dB is 3/4 of the signal lost. (Not that it matters).
6dB is typically only one "S Unit".

[nd5y]

I have one of those and they don't seem to be real accurate.
Are you measuring coax loss with the antenna connected? It won't work.

[Wyandotte]

Originally Posted by nd5y

I have one of those and they don't seem to be real accurate.
Are you measuring coax loss with the antenna connected? It won't work.

Yes, that's exactly what I am doing. Oh well, I'll never know then. I'm not going to go back up and disconnect the feedline from the antenna just to find out what the coax loss is. Thanks for the help.

[n8emr]

I beleive the line loss must be done with the antenna disconnected form the coax. I suspect its attached in your measurements. 30ft of 9913 has about 1db of loss, even at 1000ft is only has 4db of loss. Either you have a bad cable or are not using the meter correctly.

[mrweather]

In power, a 3 dB decrease means a loss of about 50% of your original signal. A 5.8 dB loss means your signal is almost 1/4 of its original strength. That's large but practically 3 dB represents about one S-unit so you're down almost two S-units. Not huge but not insignificant either.

9913 is known to be good coax provided it is properly waterproofed. If you have an old and "wet" piece it's going to be all screwed up.