MFJ-259

[lords]

Man I want to just say this thing kicks some major a$$
unReal .its like a whole new life for me I mean I am tuning everything ..I even trying to tune my body for 11meters

Question though when tuning a mobile antenna
does the longer shaft change the Resistance or does the ground from the vans roof change this...meaning if i add ground wires to it will i get 50-52 Ohms because right now it stands at 1.2 SWR on all 40 channels but at a resistance of 57-59 ohms
I thought this is due to me adding a longer bottom shaft extension
or maybe something with my Ground(roof of the van) its got 18' of coax

 

[W5LZ]

They are nice, aren't they?

I'm afraid your question just doesn't have that simple of an answer. All of the things you mentioned have an affect on impedance, none of them have ~only~ an effect on the resistive part of impedance.
What were the two readings for that 1.2:1, as in the 'R' and the 'X'? (I seriously doubt if the 'X' was zero, not that it's going to make much difference, I'm just curious.)
Quite frankly, at 1.2:1, you'd be better off quiting while you're ahead - lol!
- 'Doc

 

[Beetle]

Quite frankly, at 1.2:1, you'd be better off quiting while you're ahead - lol!
- 'Doc

Agreed, 'Doc. With an SWR of 1.2:1, you can lose sleep and sweat bullets to try to reduce it to something allegedly "better", OR you can get on the air and have fun.

Radio life was so much easier in the days of pi-net output circuitry when the average ham didn't much know about SWR meters, much less OWN one, and MUCH MUCH less even know about antenna analyzers! If the antenna loaded, you worked your DX all day long!

Lords - as 'Doc said, any changes you make in the antenna will affect BOTH resistance and impedance, and the '259B will show that. Make small changes, note where they take you, and make the next change to line up with that. Sort of like plotting a curve, but you get to pick the points!

 

[Crusher]

Yeah I bought me a 259B about a month ago. For some reason(hint), it works much better when you keep new batteries in it. A friend and I set up an antenna. we got the SWR to be flat. But later we discovered we had alot of reflected. After you use analyzer, double check with a bird or some other meter to see if it coincides with other device. (I think we had weak batteries and a few other variables that played against us). But they sure make it easier to get you in the ballpark quick. Also comes in nicely to test that dummy load to see if I blew it up after some heavy testing. Also comes in real handy if you have alot of jumpers and stuff really nice checking system to see if any shorts, breaks or what have you.

 

[lords]

not a problem my 1.2:1 is great and me was answered
thanks,dudes

remember this is a 259 not the 'B' model but i see much wasn't changed
and yes Crusher,with all items that take batterys you have to watch that...

 

[W5LZ]

The biggies about the '259', 'B' models, or the rest of them is that they are battery hogs, and too @#$ many screws to get out to replace them.
When you run out of things to measure with the '259' (whichever model) and get bored, lay your hands on the 'GDO' coils for them. That ought'a keep you busy for years!
- 'Doc

NEVER drop one of them, you'll regret it!

 

[park]

I have had a MFJ-259 for about five years and it's one of those things you don't get rid of.

 

[Captain Kilowatt]

I love my 259B. I have a set of nickel-metal hydride batteries in mine so I never have to replace the batteries. Now if I could only remember to plug it in to recharge the batteries I would be all set.Oh yeah,don't do like I did and accidently change the impedance referance to 75 ohms.You will think you have things tuned perfectly and then when you hook up a radio you will have PERFECT 1.5:1 SWR.

 

[Beetle]

Probably a dozen years ago, I bought a 249 (forerunner of the 259 and fore-forerunner of the 259B). When I picked it up in Vegas at AES, I saw the upgrade kit was available so I splurged and got it. A simple modification and I had the equivalent of the original 259. I now have a 259B and wouldn't part with it.