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If homebrewing a GM, is there really a need to use the same type of RF choke, surely a torroid type choke would perform the function much better, and with a higher choking impedance? As for the Vector 4000, I'm sure the debate will continue, opposing currents tend to cancel each other out, what...

Height plays a big part in what you hope to achieve, especially if we are talking about trying to work the other side of the World on a regular basis, or content with a maximum of a couple of thousand miles, the arrival angle for signals from different parts of the World should be in your...

Want to make you're 1/4WL antenna a super antenna, well you're going to have to drive a long way to the sea, but if you ever find yourself by the coast, get as close to the sea as you can, it makes a monumental difference to radiation angle, if you imagine the classic donut shaped radiation...

When we talk about 1/4WL, 1/2WL, 5/8WL etc we are talking about a physical length, as can be measured with a tape measure, the real world length of something, ANYTHING that doesn't exhibit this real World length can't be a 1/4WL, 1/2WL, 5/8WL etc, it will be a short loaded 1/5WL, 1/6WL, .21 WL...

Same problem with the mic lead on my IC7000, however it hasn't got to a bad state yet so I'll hold off buying a replacement, there's copious amounts of tape to go through before I splash the cash :D

If the last 3 feet is folded back over itself then it will effectively shorten the total length of the antenna by 6 feet :ohmy: The reason for this is straight forward, the current flowing along that extra 3 feet will be in the opposite direction to the current flowing in the antenna, these...

Just be wary of my BSometer, I couldn't possibly admit to regularly doing 100MPH on UK roads, and forgetting an antenna was on the roof :blushing: so approved testing facility it is :D

Through extensive research, and on the track of an approved testing facility, I can confirm the Wilson mag will hold the similar sized Sirio 3000 on the roof of a compact car at speeds in excess of 100MPH :thumbup1:

I take my FT817 with me when working overseas, I had a great time in Crete (SV9) last year on 10m using a miracle whip, over 400 QSOs and still managed to work Canada and USA with 500mW SSB, 10m was in great shape. I'm currently in NE Spain (EA3) and whilst 10m isn't in such good shape, 20m...

My antenna modelling skills are somewhat limited, but to give you an idea of what would happen to a 10m inverted /\ dipole at 7m high to the centre and sloping to 6m to the ends, it becomes pretty much omni directional with a total gain (including ground reflected) of 5dBi at 19 degrees, with a...

A much better improvement would be to add length below the coil, if you can fit an extension tube to the antenna, and move the coil higher, you'll get closer to a genuine centre load and move the loading coil further from ground and the car body, less loss, more efficient and greater current...

Steve Hunt's, G3TXQ, choke data is is a golden gift to anyone looking for free, easy to understand, information with regard to coax chokes, it's my one stop shop for data on the subject ;)

A ferrite choke is a piece of cake to make, however just checking the figures for a coax choke, if single band is all you need (I was thinking multiband) then 5T of RG58 or RG213 on a 4.25" air cored former will give a very respectable figure for 27MHz, any more turns than that and the high...

Maybe I'm just a cynic, but anyone that is able to computer model the antenna, and find exactly the same results as the manufacturer claims, doesn't really need the advice of this forum's humble users, in fact I'd go as far as to say you could write advertising copy for the manufacturer, maybe...

The whole purposes of the RF choke is to impede the flow of common mode current on the coax, an vertical antenna that doesn't have any radials / ground, requires the coax to form the other half of the antenna, this being the case then the coax choke will fail in it's purpose, it won't be able to...

A 1/2WL vertical, which the A99 is, without a good ground radial system, uses the coax outer as the 'other' part of the antenna, installing a coax choke is unlikely to have anywhere near enough impedance to stop common mode current on the coax, and if the antenna is mounted on a metal pole then...

An interesting comparison, I'm assuming the antennas are the same length, only the method of tuning differs, were you using counterpoise wires?

Maybe it's just me, but how do you get two 57" halves from a 102" whip :unsure: if the antenna is truly a half and half of equal length, then you'll be 6" short of your 57" goal :ohmy:

Not really sure what you mean by 'keep things in perspective', what things are you talking about :confused1: We can compare antennas to anything we like, however the normally accepted standards are an isotropic radiator and a dipole in free space, and, just like the isotropic radiator, a...

I guess you're right, in that a dipole will never have gain over a dipole, just as a three element yagi will never have gain over the same three element yagi ;) however a dipole does exhibit gain in the order of 8dBi at just over a half wavelength high, it will also exhibit very low angle...