looked up the losses for lmr 400 at 100 ft. at 30 megahertz and it shows 0.7 so at my 150 foot run I am looking at around 1.4 db loss which comes out under 25% loss if we use 3db at 50 % loss per previous post . Even Heliax is only a little better at around .5 for the 1/4 inch reasonably priced stuff . So I guess I will stick with my antenna , 50 ground radials, 150' of lmr 400 and 1.4db loss . unless there are any other suggestions. thanks to all . John Molenda
Where are you getting those figures from? Your losses are far more than that. 1.4dB is for a 1:1 SWR. Your SWR isn't 1:1
From the eHam article quoted you have the following:
160m - 30dB loss or approximately 99.9% of your power being lost. Basically for 1kW out of the amp, barely ONE WATT will make it to the antenna. If you're making contacts on top band you're proving QRP works!!
80m - 11.4dB loss or approximately 90% of your power being lost.
40m - 1.6dB loss or approximately 25% of your power being lost.
30m - 5.2dB loss or approximately 70% of your power being lost.
20m - 5.6dB loss or approximately 75% of your power being lost.
15m - 4.6dB loss or approximately 60% of your power being lost.
10m - 1db loss - negligible.HOWEVER you not only lose on transmit but receive as well
so on 160m, a signal would only be 1/1000th of the strength it should be if you used an antenna coupler.
If you used the MFJ you mentioned then your losses would be 1.4dB or thereabouts but as you can see from the above, they're a shedload more than that at the moment.
A friend of mine changed from a shack ATU to an antenna coupler at the feedpoint of his long wire after being sick of listening to me banging on about ATUs being pointless to use except for matching small mismatches such as 3:1 or lower. He not only hears stuff he has never heard before on it but can get out further with 100W than he used to with 1kW.