with differential flux were WRONG, and based on some careless experiments I did more than ten years ago before I started working with ferrites in any serious way. Based on questions from others, I r
I dunno. There's no "typical" or "standard" common mode source and load impedances, and they're harder for hams to calculate and control. I think the best you can do is publish the impedance and the
I'm using a bunch of 2N4401 NPN transistors ('bout the same as a 2N2222) and some P channel MOSFETS to do exactly what you're suggesting (circuit to the left). I think the MOSFETS are IRFU5305's but
This is my favorite example: http://dayton.hq.nasa.gov/IMAGES/LARGE/GPN-2000-001879.jpg <http://dayton.hq.nasa.gov/IMAGES/LARGE/GPN-2000-001879.jpg>The surface of the shuttle launching pad is about
Well, here it's captioned that "Lightning strikes the launchpad" http://earthobservatory.nasa.gov/Newsroom/view.php?id=22745 but this is some press release written 19 years after the fact and probabl
That's one good reason. I think we'd do it anyway because it's so much easier to put the antenna perpendicular to the tower and have everything work right. There are mechanical and electrical interac
In the main window, click on "Desc Options" and you can get it to plot Vertical and Horizontal separately, with or without the "total" field. I also have options for circular polarization but I think
and driven element length to tune it at ground level, but the info with it is vague as to the process. And, I cant uncover a correlation that would permit me to pre-tune it at ground level that tran
Had the exact same problem with the rotator at the base of the 30 foot rotating mast that supports my 20m Moxon. Strapping around the rotor cured it. _______________________________________________ _
Don't forget to rotate that 5:1 mismatch around the SWR circle on the Smith chart. Not all 5:1 SWR possibilities are the same in terms of high power matching. Even 250 ohms is way better than 10 ohm
Sure, why not? Short lengths of coax with the right mismatch can show what you might call mismatch gain... the mismatched line has less loss than the matched line. I think calling this situation "mi
I don't know how to decide on the resonant frequency (besides doing a systematic modeling study) of the traps to absolutely optimize it, but I think anything in the vicinity of a few hundred kHz belo
Not true. An EZNEC model shows that a 110ft dipole 30 feet above ground* resonates at 3.64MHz and 7.13MHz when 39uH coils are added 11 feet from each end. The 2:1 SWR bandwidths are narrow (100kHz o
I had this same consideration when I was choosing top guy ropes for my 60 foot Spiderbeam vertical. "Stealth" wasn't *exactly* the primary goal, but I wanted the guy ropes to be pretty visually unob
On 80m each radial will be a very high impedance. On 160m it will add a lot of reactance at least. What you're really doing if you do that is making loaded radials by inserting a shorted, lossy (bec
!!!!!!!!!! The pattern is remarkably weird. I tried a square loop at 50 feet above "average" ground on 160m and 80m, fed in the middle of one side. http://n3ox.net/files/hugeloop.jpg It's basically
It is a little interesting that at 50 foot height, the pattern of a single 6600 foot center-fed wire has a single clean lobe on axis and the low angle gain is quite high. Might be uselessly narrow be
I think your easiest bet is to use a computer and software like DXLab. If you don't want a general-purpose computer in the mix, or if you really, really want a knob, I'd look at talking to the RS-232
But it's not going to be [i]stiffer[/i] which is what you want if you're worried about the sag when raising it. The modulus of elasticity varies very little across types of aluminum... different all
Might it just be that the demand for the form factor of parts that industry needs has changed completely and we haven't re-worked our designs and expectations? I wonder what the performance hit (if a