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antenna recommendation

I have used the Coily and the Predator on my Ford pick up truck and they are tuning from about 25 MHZ to 28 MHZ with an swr around 1.5 to 1 or so. I am getting 1.2 on channel 20. I replaced my Wilson 5000 mag mount with the Coily and Predator and the difference was amazing. Better transmit and receive. Easily 2 s units on receive from locals talked to from the same location. I am using a Valor tri mag mount with 18 feet of rg8x. I wonder if the user of the Peterbuilt had the proper length shaft for their truck. I am a little surprised that the Van Ordt Power Stick beat the Predator which I thought would have a higher gain factor(Q). I believe that the Power Sticks will handle arould 750 watts AM and 1500 SSB. I realize in theory that top loaded antennas should beat out center loaded and base loaded antennas in most circumstances but in the field this does not always occur. Maybe Dan or Kale could chime in and make some suggestions. I think the Tigers and Power Sticks are good. Also you might consider Skipshooters.
 
"I realize in theory that top loaded antennas should beat out center loaded and base loaded antennas in most circumstances but in the field this does not always occur."

that it occurs over 50% of the time is substance enough. the perceived performance numbers would be higher if field variables were eliminated. in the field working with tractor-trailer rigs it occurs more times than not. given any randomly selected low angle of launch, the loading coil has to be high enough up on the shaft of the antenna to radiate the signal out over the top of the trailer. if not, then the bulk of the energy in the rearward direction is absorbed and re-reflected back from the front of the trailer towards the front of the tractor at the same angle as it arrived, leaving the back of the trailer a dead spot for transmitted and received signal.

unfortunately, because of clearance limitations, merely adding a longer shaft and retuning the antenna doesn't solve the problem in a mirror mount situation with an antenna that is already 60 - 66" long. 5 1/2 foot could be a clearance problem unless the truck is booted with 22.5 lo pro (tires) rubber.
 
"What i posted are facts 450-800+forward swing 100+ mod loud and clear."

your equipment works (or doesn't work) the same as every one elses. (except maybe your modulation meter) the fact that there is an integral relationship between the total sideband power and the resting, unmodulated carrier when it comes to determining the percentage of modulation of an am transmitter doesn't change for you or anyone else. in your case, as i mentioned before, regardless of what your meter tells you, either one of two things are occurring.

you're measuring peak envelope power and at 450 - 800 your signal is undermodulated, or:

you're measuring average power and at 450 - 800 your signal is overmodulated. those are the facts. the point you made about it being your equipment has no bearing on the discussion whatsoever. i told you there was nothing to argue about because the numbers you mention (450 - 800) are in no way representative of a 100% modulated signal regardless of whether you're measuring AVG or PEP. if you're measuring PEP and you want your equipment to perform better then lower the carrier to 200 and if you can keep the 800 on top from there then you'll have 100% modulation. if you're measuring AVG and you want better performance then up the carrier to 530 and keep the 800 on top or keep the carrier at 450 and limit modulated output to 675. period. if you have a modulation meter function in your test meter that's telling you that 450 - 800 is 100% modulation, IT'S WRONG! i do seriously suspect that the mod meter calibration is not as it should be, for one reason or another, from either unauthorized tampering or damage. i calibrate the stuff and i know you guys like to get in those things and play, especially when i see the "busted" look on your faces when i begin asking questions. not saying you did, but something to consider, especially if purchased second-hand.

thanks for the beer but i don't drink. i find that alcohol dulls the mind and makes some people stupid. you can have mine. don't take it personally.
 
newride4nh.jpg
 
Its cool!

freecell said:
"What i posted are facts 450-800+forward swing 100+ mod loud and clear."

your equipment works (or doesn't work) the same as every one elses. (except maybe your modulation meter) the fact that there is an integral relationship between the total sideband power and the resting, unmodulated carrier when it comes to determining the percentage of modulation of an am transmitter doesn't change for you or anyone else. in your case, as i mentioned before, regardless of what your meter tells you, either one of two things are occurring.

you're measuring peak envelope power and at 450 - 800 your signal is undermodulated, or:

you're measuring average power and at 450 - 800 your signal is overmodulated. those are the facts. the point you made about it being your equipment has no bearing on the discussion whatsoever. i told you there was nothing to argue about because the numbers you mention (450 - 800) are in no way representative of a 100% modulated signal regardless of whether you're measuring AVG or PEP. if you're measuring PEP and you want your equipment to perform better then lower the carrier to 200 and if you can keep the 800 on top from there then you'll have 100% modulation. if you're measuring AVG and you want better performance then up the carrier to 530 and keep the 800 on top or keep the carrier at 450 and limit modulated output to 675. period. if you have a modulation meter function in your test meter that's telling you that 450 - 800 is 100% modulation, IT'S WRONG! i do seriously suspect that the mod meter calibration is not as it should be, for one reason or another, from either unauthorized tampering or damage. i calibrate the stuff and i know you guys like to get in those things and play, especially when i see the "busted" look on your faces when i begin asking questions. not saying you did, but something to consider, especially if purchased second-hand.

Well i am cool with all that man i know what your saying don't get so worked up.I a have all the equipment its all good.Have a good day If bird pep is wrong then whats right?if my radio does a 100% mod with 800 watts swing then i am sure it will with 300-400or 450 swinging to 800 watts.its cool i understand totaly peace...Coily waving!
Click to expand...
 
I am not sure what DX is trying to say either. But the tractor and 4 wheeler look fun, or is it a 3 wheeler. Freecell would the tractor trailer have worked with a 22 inch or 27 inch coil antenna. That should have gotten the coil above the cab of the truck. But I understand what you are saying about antenna height. A good quality 5 foot antenna that is top loaded may be the best for that particular installation. Great posts and well thought out.
 
someone wrote........

"The trailer is almost too far away to be a usefull contributor although it will definately have an effect on the pattern. Most likely it acts as a shield for the most part."

the further away the nose of the trailer from the mirrors the better. it also depends on how high up the antenna the base of the loading coil is located. if we look at a straight line with a 20+ degree angle above horizontal starting at the base of the loading coil and move towards the nose of the trailer either one of two things will occur. the line moving away from the base of the loading coil will impact the front nose of the trailer or it will pass over the top of the trailer. if we can get it over the top of the trailer with the trailer roof underneath it, we can establish launch. the two easiest ways to do this is to move the antennas further forward away from the nose of the trailer or raise the height of the loading coils, either by adding a longer shaft or selecting a different antenna design. under these conditions the signal off of the back of the trailer can be 30 - 40 % more intense than the signal to the front and is much less "skewed" and more "uniform" than you would imagine. relatively speaking, if the base of the loading coil is not high enough to deliver any low angle radiation above the top of the trailer then the back of the rig remains "dead" when referenced to the signal produced to the front.

co-phasing or phased array:

a group (2 or more) of antennas in which the relative phases of the respective signals feeding the antennas are varied in such a way that the effective radiation pattern of the array is reinforced in a desired direction (or directions) and suppressed in undesired directions.

The relative amplitudes of--and constructive and destructive interference effects among--the signals radiated by the individual antennas determine the effective radiation pattern of the array. A phased array for our discussion is used to direct a fixed radiation pattern. for the purpose of the over-the-road truck driver, the most useful directions with relationship to the position of the tractor-trailer rig would be to the front and the rear of the rig, a bi-directional pattern being the most desirable, perpendicular to the plane of the array.
 

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