I may be way off base with this thought but , what if I put my antenna analyzer at the base of the antenna and take readings will these readings indicate what I might see with a remote antenna tuner at the base ? Always thinking :>) John kb2huk
The MFJ 259 series is not terribly accurate away from 50 ohms, and really most Ham type gear is not that good away from 50 ohms. You can really come out closer with a model, short of actually measuring the antenna on a VNA.
Long feedlines below upper UHF are dominated by resistive loss in coductors, so the loss is CURRENT related. Since loss is current related we cannot really use SWR on lines that are not near a half wave long or longer. There have to be at least a few standing wave impedance cycles along the line for SWR based loss calculation to be accurate.
You have a long transmission line, 150 feet. SWR works fine determining loss when the feedline is long in wavelengths, so for 80 meters and up SWR values are very useful for predicting loss. On 160 SWR might not be completely useful on your 150 foot line. 160 will be terrible anyway, so why worry about it no matter what the line loss is?
Move the tuner to the antenna base, or switch in a base loading coil for 160 and 80. Do NOT expect to get away with 1500 watts on 160.
According to the eham article the loss for 150' of LMR400 feeding a 43' vertical is:
80 meters 11 dB
40 meters 2 dB
20 meters 5 dB
15 meters 5 dB
10 meters 1 dB
That's reasonable and the only bad bands 80, 15, and 20 meters. 160 will be terrible.
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.
First of all, we should remember the RECEIVER end of the system sets SWR on receiving. Not the antenna. On receiving the radio is the load and the antenna is the source.
More important, it takes a horrible receiver for line SWR or antenna mismatch to hinder or affect reception. A loss in efficiency or gain does not affect receiving so long as the antenna pattern does not change shape and the system limits by noise the antenna picks up. It is a common but absolute myth that improving antenna system gain always improves reception. There is usually 5-10 dB headroom for loss on upper HF, and 20 dB or more headroom on the 160 meters.
This is why 0.1% efficient antennas on 160 can hear the weakest DX on the band that can be heard at a location, and why small loopstick antennas and whips work to get all the way into atmospheric noise on 160.
A ten meter system, because it is quieter on ten meters and there is less signal power level, might require a few percent antenna efficiency to get into propagated noise floor.
I would not go overboard expecting to hear new signals from reducing the loss he has on the feedline on any band.