Mudduck but smart enough to ask before tragedy

[PYRO-736]

Ok here we go.

Have been out of the game for a little bit, power wise. Had a setup in TX. Was a 4 pill with a Texas Star Mod-V as a driver. Came up here to NY after the military and ran a 667V with connex 3300. Im in the last stages of hooking up a North Carolina DaveMade 16 with a 5 pill driver. I had an alternator bracket fabricated and 3 high output alternators built and installed a battery box in the back of my Jeep. My charging system is squared away just hooking it up this week. Have all my grounds ran and everything.

I have a Fat Boy puck mount, I have RG- 217 for coax. I have a Bird 43 with dual gauge for power and reflect and I also have a telepost 100A inline swr meter.Have always heard conflicting reports from people into it whether to tune the swr's with or without the boxes on or off. Dave(joe) that made the boxes says 1.3 or under with the 16 goin. A lot of people that operate big systems here say with the boxes off. When I had the 4 pill going I tuned it with the boxes running without worrying too much about it. The 16 though is a whole nother ball game and dont want to have to pay to repill the boxes. Any input would be great. Id rather ask now then possibly recall from the past incorrectly and have that smell of burnt transistors in the back of the truck and watch the reading on the bird dip to almost nothing.

Thanks again..............

['Doc]

The thing with SWR is that it's an impedance ratio. That means that SWR will not change as long as that same ratio is kept/maintained. If you get a 1.1:1 at 4 watts, it'll still be 1.1:1 at 400 watts or 4000 watts, or 400K watts. SWR does not change with power, it only changes with the relationship between the impedances of the antenna system. The only benefit from checking SWR at higher power levels is to see if the system will be capable of handling that power level. That's not a very good way of doing that, there are things other than just SWR that can make that kind of difference that an SWR meter can't tell you anything about.
- 'Doc

[PYRO-736]

Thank you for the response doc. Ill be running the double coil Predator 10K also and what you just said set me at ease. Thanks again

[PYRO-736]

Just one more thing doc I do have a MFJ 259B analyzer as well, so I shouldnt have too much difficulty tuning the system. I bought everything I would need piece by piece so when the time came I wouldnt be lacking any tools.

['Doc]

I think an MFJ-259 is one of the better things to use with antenna tuning. (Not just the MFJ analyzer, but any of them.) It can tell you quite a lot that would other wise require several different meters.
That '259 has three things it's telling you, SWR, 'R' resistance, and 'X' reactance. One of the most informative things you'll find out is that while the SWR may be low, the 'R' and 'X' can be just about any value. That 'R' very seldom comes up 50 ohms, what you would normally want, and that SWR is still pretty low. At the same time, that 'X' value can be all over the place. The combination of those two, the 'R' and 'X' is what makes up impedance, which is what that SWR meter is measuring. The -ideal- is an 'R' of 50, and an 'X' of zero, which is a 1:1 SWR. The bad part of the whole thing is that the 'X', the reactance present, doesn't 'do' any radiating, doesn't 'make' any signal flow, only the 'R', resistance does that. What all that says is that while you may have a near perfect SWR, that antenna isn't doing what it could/should be doing.
That '259 has a lot of other uses too. How about as a 'grid-dip oscillator'? Something else you won't have an everyday use for, but every once in a while...
- 'Doc

[PYRO-736]

Wow thanks for the headache doc lol- Seriously though thanks for the info. I just have the belt sizing that Im doing tomorrow and to wire the variable regulators for the alternators that will be charging the battery bank for the big box, clean up and coat my grounds with some dialectric grease(the shop I had do them wasnt exactly on the ball so will go over everything they did with the grounds) and re hook up the Positives for alt. to batts. in the back of the jeep. Then is on to antenna. Ive been reading the manual that came with the MFJ on and off over the past couple of months but seem to have ADD with all the terms half of such were all the ones you mentioned but I will get it.(right about now is when I wish I had taken some electrical engineering and other classes). Thanks again doc