Hi,
I found that I get a different readings on the MFJ971 SWR meter after I tune the antenna with the RigExpert.
For hard to tone right, I though it will be easier to tune with the analyser but going back to the tuner’s SWR I get way higher.
From 1.8 for example to around 2.8 jump.
Any technical/theory details that Im missing?
73s
Tasos
You don’t say what antenna you are testing or how you are testing it?
Are you measuring it at the feed point or on the end of a length of feeder?
I think we need a few more details to be able to help here.
Trying to compare different meters, especially after you remove one meter, add in another, plus some more cable to a transmitter and transmit again adds in a number of variables.
If I were asked which meter I would trust, a simple Voltage Standing Wave Meter (VSWR) or an analyzer, I’d go with the analyzer as it tells you a lot more about what is going on.
You said two things to worry me “MFJ” and “SWR” what you want to know is, is the antenna and feeder resonant on the frequency that you want to transmit on, is it providing as near to a 50 ohm resistive load as can be expected, how good are the meters that you are using and over what range of inductive or capacitive loads are they able to work?
What you say suggests that the VSWR meter is probably quite limited in the range of impedance that it can cope with and give reliable results. But I could be wrong.
Dave (G0DJA)
Thank you both, I must explain more about my setup.
I measure the matching on the radio side. Measuring between the ATU and the rig. MFJ971 is my tuner.
I’ve got a 35feet long wire (cut in one of the ““good”” lengths) with a 9:1 unun and 15m rg174 coax. Its connected to the tuner and after the tuner (between tuner and 857d) I have a 3to1 coax switch so I can check the SWR with the RigExpert AA54.
The band I last checked is the 80m which admittedly its not the most efficient band for my setup as far as I understand. Of course without a tuner the antenna is not resonant on any band (plus I used a C++ code to check not only the fundamentals but I think up to the 4th too)
So if I tune the tuner with the help of the analyser, down to a nice 1.8-1.9 and then go back to the rig and transmit… I get at least 2.6-2.8 SWR.
I hope that helps.
Thanks
Tasos
I’ve just realised what you are probably doing… Why are you looking at the output of a “tuner” with an analyser and worrying about the “swr”?
You are probably going to have some horrible common mode currents causing havoc with the system you have discribed on 80m
so the tiny output of the analyser can really describe the situation…
I did try to use a choke a couple of weeks ago but I probably did it wrong and I didn’t get a good result.
Your MFJ tuner will “tune” a random wire. Have you tried just a length of wire (without the un-un) and a counterpoise to see what happens?
its hard to setup this configuration, the tuner than has to be outside 
Is this an antenna for home or portable?
I know confusing, but its a portable setup used at my QTH though at the moment. (the only antenna I can have at my current location)
Its a 10m fishing pole with the above config. For portable I use the same 9:1 long wire with a Zmatch QRP tuner and a 7m fishing pole.
Hi Tasos,
I’ve never used an antenna analyser myself but I can tell you about my experience with SWR and antenna tuner.
I guess your radio has got a built in SWR meter. So it has mine and that’s the reading I always look at when tuning the antenna with the external antenna tuner.
In my set-up, I currently have the antennas, the coax lines, the coax switch, more coax line, then the antenna tuner, more coax line, then the amplifier, more coax line and finally the radio, a Kenwood TS-940S.
My antenna tuner has a SWR meter but I always tune it for a 1:1 SWR reading on the TS-940S meter.
When this reading is achieved on the rig SWR meter, the antenna tuner SWR meter very rarely shows 1:1 SWR, almost never.
But, to me, the purpose of using an antenna tuner is giving a 50 ohm impedance to the radio and that’s what happens when the radio’s SWR meter shows 1:1. I don’t care much about the rest, as long as it’s not higher than 2.5:1 or 3:1 on the antenna tuner SWR meter.
The fact is different lengths of coax lines, switchers, connectors may produce impedance changes, thus bad SWR.
My advise is that you always look at the SWR reading on your radio built in SWR meter.
Best 73 de Guru - EA2IF
Making an antenna “wide band” is always going to be a poor compromise whatever you try to do, even more so with a small (compaired to wavelength) vertical antenna. Have you room to fit a 50’ doublet (1/2 size G5RV) at home?
Which if you are using an amplifier like you are, will not tell you anything about your antenna - it will be telling you how good the match between your transmitter and the input circuit of the amplifier is.
FUNNY!!! I wish!!!
Even this is pushing the limits! Im on the 6th floor with a 30cm space outside the full height window.
At least my 10m pole gives me a nice start over most of the buildings in central london 
I do get very good QSOs between 10m and 40m so I can’t complain. Now with the bad solar weather I had to go lower to find activity.
Some wide-band antennas are very effective. Obviously, a log-periodic works, but low-Q antennas (cage dipoles) work just fine. W1AW put up a cage dipole that covers the whole 80m band with low SWR.
If you get a wide band by adding resistance, that is not a good idea.
wunder
I forgot saying that I’m not currently using the amplifier, although it’s still connected in the line.
My TL-922 AMP has been off for several months, however, when I was using it I used to tune the external antenna tuner for 1:1, so the amplifier saw the good impedance and then, at the radio, I used the TS-940S built in ATU (automatic antenna tuner) so it also sees a good 1:1 SWR.
Have a nice day!
73,
Guru - EA2IF
That information would have been useful at the beginning.
Have you thought of hanging a W3EDP/Zepp antenna from your pole?
I googled it, not sure if I got the right one.
The ladder line might fit (5-6m I think), bent following the current coax with a couple of meters outside, but the long active element is very hard to fit! 25 something meters. more than twice the length I manage (with a lot of strangle) to fit now.
Thanks
Tasos
A W3EDP is inappropriate for two reasons. Firstly it is 26 metres long, and secondly it needs variable counterpoises. Its a great all-band antenna but he doesn’t have the space for it.
I would suggest taking the amplifier out of line, it is bound to introduce a small loss when not powered up.
Brian
I conceed a “zepp” is a bad idea.
As I have no experiance of restricted space hf antennas I am out of this conversation.
Carolyn