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RigExpert AA35
- Thread starter jdchet
- Start date
Looks like you're learning it. These are wonderful tools to have and they're not as complicated as they seem at first.
A far better choice you made going with Rigexpert analyzers than the antiquated MFJ-259.
A far better choice you made going with Rigexpert analyzers than the antiquated MFJ-259.
Z and R need to be as close to 50 ohms as possible.
X needs to be at ZERO or as close as possible.
RL needs to be as high as possible 40~60 db
Move the ranging out to 100khz, it will give you a better overall picture across the band.
I use my 55 Zoom with the ranging set at 500Khz .......
X needs to be at ZERO or as close as possible.
RL needs to be as high as possible 40~60 db
Move the ranging out to 100khz, it will give you a better overall picture across the band.
I use my 55 Zoom with the ranging set at 500Khz .......
Okay...........here's where I head down the rabbit hole............JK
Where can I find good info on the causes and remedies for the above readings? I am willing to learn the right way to fix my antenna system so that it is the best it can be.
Somewhere down the road I intend to have a base setup and, dare I say, go legit (ham ticket)!
JD
I'd just use the antenna as-is. Looks fine for now. 1.41:1 is a good SWR at 27.385 Channel 38. The SWR improves as you move down, and has a minimum at 27.245 Channel 25. It should be fine on Channel 19, just on the other side of the minimum. What are you trying to tune? A mag mount? A base-loaded antenna on a thru-roof mount? A center-loaded big coil antenna on a mirror mount? A Firestick on a stake-bed pocket mount?
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Big truck. 5 foot Firestick2 on a bird perch mount. Volvo sleeper truck. JD
Ah. Slowmover probably has more helpful info, as he drives OTR. The K0BG.com site is geared toward the mobile ham operator in a standard passenger car or truck, but there's still a lot of good info.
I have a 2 ft Firestick clone on the Class C RV (Ford E450) on a hood channel / front fender mount. I trimmed it to resonance on 27.325 MHz, Channel 32 or so, not by choice but because that's where I ended up with some over-aggressive pruning. The sleeper overhang leaves exactly 25 inches of clearance from the hood to the bottom of the sleeper bunk, so the "tunable tip" antennas don't fit. Had to use the old fashioned cut-to-tune type. The Bearcat 880 is fine with the SWR from Channel 13 to Channel 40, but below Channel 13 it starts to roll off the output power. A 2ft antenna is pretty narrowband and can't be trimmed to cover all 40 channels reasonably, though. Your 5ft Firestick2 should be easier to tune, as they get more broadband the longer the antenna.
Maybe try some 1/4 inch snap-on Mix 31 or Mix 43 ferrite beads at the feed point to reduce any common-mode currents coming back down the coax. Here's the 1/4 inch diameter for RG-58 or RG-8X cable.
For RG-8/U or RG-213, you use the 1/2 inch diameter beads.
If they're out in the weather, you can put an extra zip tie around them to keep them in place, and a zip tie on the outer jacket of the cable below the bead to keep it from sliding up/down the coax. But other than that, I think you're done for now.
If the antenna is resonant where you want it (reactance X=0 at the desired frequency) and you want to improve the match further, the MFJ 907 tapped transformer (https://mfjenterprises.com/products/mfj-907) placed as close to the antenna's feedpoint as possible can improve the match. A vertical antenna with proper grounding and resonant at the operating frequency is always going to have an impedance lower than 50 ohms and require a transformer to bring it up to 50 ohms. But I would think any standard sideband radio like a Bearcat 980 or President McKinley will be happy with 1.41:1 SWR on 38 LSB and not be rolling back its output power to protect the finals.
If you're going to be running non-FCC approved power, I'll defer to the folks who know about the matching/SWR requirements for those devices. Looks like an AnyTone AT-6666 in your avatar, so there's probably some SWR requirements or a spec in the manual for that radio. I think it does 15 watts AM carrier and 60 watts swing, with SWR protection that triggers if the SWR is too high.
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Now that I have a proper tool to see what's going on, I'll fiddle with ferrites and bonding to tighten things up. DX Engineering is right down the road from me so that helps (not my wallet)! JD
Be happy with what you get with a bird perch if it’s up high (door spot mirror).
The ones used at the big mirror base can take a genuinely tall antenna. That, and as a cophased pair work better (7’ Skipshooter pair on a FL Evo) is my experience
Bird perch on spot mirror on this 579 Pete NOT as good using A-pillar factory cab mounts. (Same exact antenna).
I pull a van. A tanker might get better results, same with flatbed.
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Mr Applegate does an unparalleled job of taking things apart and showing how attention to the parts of a component (in a manner of speaking) pays real dividends.
An example is that noise-control won’t overcome a bad antenna mount or vehicle position. (See photo gallery for ideas with box truck type). So once we’ve done what we can, then it applies.
Another example (this forum) is in attempting a dipole.
At end, big truck or Moho, we are fairly well on our own. Except where those details mentioned apply to us. And each section has enough to recommend the whole of the website.
Stationary use can be a spread of adaptations, just can’t use them while underway.
Best horizontal spread (closest to 108”) is with the stock Volvo mirror antenna mounts. While that’s outside of accepted discourse, a pair of antennas on a big truck with van gets best all-around performance, is my opinion.
it’s TOO easy to lose the other guy when he’s headed the other way. We both of us turn away from each other, and the switch is cut off when with one antenna. (Why I dropped spot mirror mount).
“Distance” is second to that, IMO.
Where a single is on a custom mount, this might be alleviated (see 4string review of Sirio 5000; see pic I added to GoldenRod 45 thread) with a model to follow.
I want to stay away from the stock Volvo mirror mounts. They don't seem beefy enough for a decent antenna. A quick look around our fleet and you will see many Volvos with only one or no stock antenna! Had the passenger side antenna fall off mine a month ago.
Not a great picture but it's just to the left of the stock antenna. Bird perch screws into mirror bracket mounting bolt hole in door.
I have yet to get serious with bonding the doors, etc. Checked ground with multi-meter and seemed alright but noise level changes when I open door so probably need to better ground the door to cab! I may just overhaul my antenna system when the weather gets warmer! I have a 5' Skipshooter in stock and I might try mounting it behind the cab on the top bar. 95% flatbed work so that might not be too bad.
We'll see!
JD
Not a great picture but it's just to the left of the stock antenna. Bird perch screws into mirror bracket mounting bolt hole in door.
I have yet to get serious with bonding the doors, etc. Checked ground with multi-meter and seemed alright but noise level changes when I open door so probably need to better ground the door to cab! I may just overhaul my antenna system when the weather gets warmer! I have a 5' Skipshooter in stock and I might try mounting it behind the cab on the top bar. 95% flatbed work so that might not be too bad.
We'll see!
JD
You should remove the factory antenna because it's in the near field of your main antenna. This will cause reflections and other issues because it's within the same frequency range as your main antenna. Be sure to put a short 3/8 x 24 bolt or all thread in the factory CB mount so the threads don't rust.
Behind the cab is a good location being you pull flatbeds and you have a flat top sleeper. Get the longest antenna you can and center it and you'll have a nice omni-directional pattern.
A 102 whip will still put you over 14 ft and it might trip any over height sensors like Eisenhower tunnel or some gestapo type D.O.T. man may cite you for it. Any part of your load or vehicle over 13.6 could put you in violation in most states.
The Sirio 5000 trucker series for example is about 80 inches and would be a good choice.
Here's mine on my when I drove a Volvo.
Behind the cab is a good location being you pull flatbeds and you have a flat top sleeper. Get the longest antenna you can and center it and you'll have a nice omni-directional pattern.
A 102 whip will still put you over 14 ft and it might trip any over height sensors like Eisenhower tunnel or some gestapo type D.O.T. man may cite you for it. Any part of your load or vehicle over 13.6 could put you in violation in most states.
The Sirio 5000 trucker series for example is about 80 inches and would be a good choice.
Here's mine on my when I drove a Volvo.
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