Keydown Thoughts on Monster Antennas

[drdx]

I thoroughly enjoyed the Jacksonville video and think the monster antenna setups are cool, as antennas are my favorite part. Those monsters are huge and stick out everywhere. What I'm about to bring up is the same argument that the car crowd has. What constitutes the difference between a real world mobile(street car, in car terms) and a trailer queen that only comes out once a year(dragster)? Those look to be the trailer queen type. They all have their place and I'm sure some run reduced setups for drive around, but that black van on there, is it dropping off kids, picking up beer, and shooting skip, all at once, on a Tuesday? Is there a class that requires the vehicle to go 5 miles at 70mph highway speeds and then pull right to the line, and key up, without adding to the arrays? Like drag week, where they drive the cars to the track? I have respect for all of them, but the real deal is the one you drive to the competition, talking all the way there, key down, drive home. I can understand throwing on a back door or a director or 2, but they need to be able to withstand the highway. I'm guessing, in that crowd, that mobile means it is vehicle based and can physically roll from the trailer ramps to the line? I am slowly but surely putting something together that I can take to a keydown someday. I have some antenna knowledge from 25 years of sitting on the throne poring over antenna books, mobile setups, beams,wires, etc., and a pile of aluminum tubing, coax, mounts, antennas, and constantly play with it, but I've always stuck to what rolls down the road. It might be 2 fighting sticks on whip springs, fed 2 hot, on potbelly springs, with a director on the front and maybe a back door, but it will go down the highway.

Also, for a given array length, in theory, there is only so much gain to be had as long as all elements are illuminated with RF. If a given boom length has 4 elements and is X long, and they're all "lit", adding more to the mix doesn't necessarily help, and can hurt it as well. Even the vehicle width plus the "wiggle room" on the outer parameters isn't enough to properly space and phase to max potential, and element interference is always a factor, as is vehicle metal proximity effect. Anyone care to shed some light on this? I see coils on there too. Why would ANYONE desiring max efficiency in that setting in particular, where height is not a factor, ever choose something with a coil in it?

Obviously these guys are the big dogs, and this is a loser either way. If it works they aren't gonna tell, and if it doesn't they aren't going to admit it. It's probably either "that's our secret", or "shows what u know, I didn't see you on the line", and those are both good arguments, just like the person that gripes about politicians but doesn't vote. I plan, someday, on "voting" (doing the keydown deal) even though I'm sure I'll be there just as a depositor, but it will be fun.

-drdx

[ww228kidd]

lol..
they way they are doing it is if it is an ordinary vehicle and you can drive it up to the line then you are good... dont try what sugar daddy did one year and bring a shorty bus... they DQed him...

most of the guys do drive tot he keydown, .. key... then drive home..but when you start to get up in the big AC classes where the motor only gets 5 miles to the gallon and the motor is running off of alcohol then the must be pulled...


as for the antennas... the books will not help you too much on a mobile setup...
it takes testing and keying

we only hot up only one or two elements then the rest is grounded or not...

i will tell you this,,,, most of us use the 5 or 6 element setups..

starting at the back antenna and going to the front...

#1 grounded or using a vacuum capacitor to ground
#2 hot
#3 not grounded and longer than the hot
#4 not grounded and even longer
#5 not grounded and even longer longer

or the 6 element system

#1 grounded or using a vacuum capacitor to ground
#2 hot
#3 hot 135 degrees out of phase ...shorter than #2
#4 not grounded and longer than the two hots
#5 not grounded and longer
#6 not grounded and even longer

if you need anymore help let me know what type of truck you have and I can send you a DVD of the keydown will clearer pics of the setups...

[ww228kidd]

oh and forgot to mention... they dont have the stock one antenna class at the bigger keydowns anymore... that is why you dont see the regular ride around trucks keying... only the one with Pain Killer and Blue Gill was a grudge match....

the antennas canot be longer than 18' long unless you are in a SKY class then anything goes..

[drdx]

Cool, that offers me a lot info wise. So the ones longer than the hots are not grounded. Are they just longer than a 1/4 wave or just slightly longer than a 1/2 wave, as in a traditional parasitic setup? For reflectivity, I'd think it would be a little longer than the half, but don't know. I know there's a good 2 hot thread out there you were on a while back that I need to re-read. I've got a cherokee with a puck going in near the rear, above the amps, and another slated to go in toward the front, and I'll feed them outta phase, just not sure if I'm going 90 or 135, or one of the other recipes that I've seen used. I've played with that stuff before, along with just longer grounded elements, as well as shorter ones, with good FS meter front to back readings. I'm only talking about a couple of kw until the ac croaks, and this is just a toy, then it's AC city for me, but something I can use frequently, not twice a year and talk about it the rest of the time. I'm slightly out of town, so for me it is as much a "help put me more in town" deal as anything. Nothing is going to substitute for location, but when the skip rolls, I want to be able to rotate and dominate in the shout back department, within the best of my abilities. -drdx

[ww228kidd]

so you need to check out POPEYE's setup.... he won a few classes with his setup ... i got a few close up shots of his black jeep .... you might wanna pulse the vid to check him out... his humber was on the side of the truck... you can prolly give him a call and let him know what you are doing.... i dont think he will mind giving you info...

[drdx]

I spotted that. Being a cherokeean, I spot that boxy look and lack of sheet metal anywhere. I'll get some time and have a look. I see that C-man on here, a new guy, is trying to get something going here in Dallas for May. We already have one coming up that a local is getting me a flyer on, so I hope to hit that one for ideas. -drdx

[ww228kidd]

POPEYE might hit that one... he is one of FATBOY's guys so he goes to alot of them...

[BattMan]

anyone coming to Jackson, MS this weekend? From what I understand there's suppose to be some of the big guys coming......not sure!