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 21 
 on: Today at 09:44:38 AM 
Started by N6PSE - Last post by NU1O
What credit did I give them?  I called them suckers, hence the quote from Barnum.

I don't think they even qualify as suckers.

The guy who invented it is brilliant though...

73,
Jonathan W6GX

Jonathan, if your only criteria for genius is making a profit that's a very low standard.  Creating wealth alone does not necessarily make somebody a genius.

I went to the "Hamsphere" website and it's clear to me that those paying the subscription fee know exactly what they're getting so my calling the creator a thief was inappropriate but I only wish the creator of "Hamsphere" had used his organizational and promotional skills to create a business which added 8,000 actual hams to our ranks.  I'm not nearly as optimistic as others that "Hamsphere" will create any substantial number of new hams.  I think most of the members are probably hams who can no longer build or maintain a station and that was listed as a selling point.

A group of us hams recently helped a 16 year old Technician gain access to 10 meter SSB.  This young new ham became aware of amateur radio through scouting.  He's an Eagle Scout and he's also involved with MRC/CERT. I think some of the tried and true recruitment methods which existed prior to the age of internet are outdated but I think scouting is still a viable way to attract new young hams.

From what I observed with this youngster, the number one impediment to gaining young new hams, aside from making the hobby known and appealing, is the cost of equipment.  We had this young ham build his own 10 meter dipole under our supervision so we didn't just turn over a station without having him learn some of the basics. However, if the HF radio, power supply, as well as the parts for the antenna and ground system were not either donated or lent, the price -- even for used equipment -- would've been financially out of his reach for quite a few years.

At the other end of the demographic spectrum, the other day I spoke to an 82 year old ham who lives about 5 streets away and whom I've known for about 20 years.  He took down his beam a few years ago when it was damaged during a storm and he replaced it with a dipole.  As we ended the QSO I made it clear to him that if his dipole ever needs any maintenance I'd be able to get it back up and functioning for him.  He said he may very well take me up on the offer and I really hope should the need arise that he does call for assistance because I know how much enjoyment he derives from the hobby.

I think it's important to recruit young hams to the hobby but at the same time I think it's important our younger hams attempt to keep the older hams on the air.  I'm not talking about maintaining towers and beams but one can still have a lot of fun with a dipole and that's real amateur radio, and not a simulation.

73,

Chris  NU1O


 22 
 on: Today at 09:28:47 AM 
Started by WD4ELG - Last post by KB4QAA
large sphere of a Van De Graff has the same purpose as the large diameter rings and doughnuts on EHV transformer terminals:  To lower the maximum electric field, reducing the creation of corona discharge.  Corona is lossy, RF noisy, and can invite mother nature to strike just where you don't want her to......

Got it?   
One uses the VDG merely as the high voltage generator.  You then place other utensils like a single pointed rod, or a wire brush in contact with the VDG and observe the discharge characteristics of the utensil.

Got it?

 23 
 on: Today at 09:27:48 AM 
Started by KB4OIF - Last post by PA1ZP
Hi John

i have build many end-fed antennas.
Wire and aluminium half wave verticals.
Both types have their own specific Z transformer and are brought to 50 ohms at the feedingpoint.

On the half wave verticals for 40 and 20 mtrs I have used over a KW only 25 feet from my shack and house.
I didn't have the slightest problem with RFI in the shack or anything else.

I now use a 5 band end-fed homebrew, that works on 10, 15, 20, 40 and 80 mtrs.
The antenna doesn't need a tuner for all bands exept for 80 it has a bandwith of 100 KHz.
The antenna is 23 mtrs long (70 feet) and if needed i have written an article in English on how to build such an antenna.

Still with this antenna no RFI problem at all and it runs over my house.

Send me a personal mail at my E-mail adres noted on QRZ if you want the article.
The antenna can handle 200 Watts PEP.
It can be bought also at:
http://www.hyendcompany.nl/antenna

though I have nothing to do with this compagny i do know both people (hams) whom run the compagny and build these antennas.

73 Jos



 24 
 on: Today at 09:10:53 AM 
Started by K0OD - Last post by N0SYA
I could listen to wlw all night long in Nebraska a few years ago. Prolly coulda heard them in the daytime at noon in Nebraska when they were 500kw.

 25 
 on: Today at 09:06:39 AM 
Started by N6YW - Last post by N0SYA
Unless it was local cops playing nsa.

 26 
 on: Today at 09:06:39 AM 
Started by K2OWK - Last post by W7EJT
check my post on this subject:

http://www.eham.net/ehamforum/smf/index.php/topic,97289.0.html

FFC (Flat Flex Cable) = Ribbon Cable


Alan, W7EJT   Smiley

 27 
 on: Today at 09:04:52 AM 
Started by KB4OIF - Last post by WB6BYU
First you have to differentiate between various types of "end-fed" antennas.  They aren't all the same.
Some can work well, some might be suitable for particular applications, and others are based more on
P. T. Barnum's marketing philosophy than on engineering principles.

An end-fed half wave antenna has a high feedpoint impedance (a couple thousand ohms) and needs
some sort of matching network, either a tuned circuit (like the LMR antennas) or a quarter wave of parallel
conductor line of the proper impedance (like a J-pole).  The same principle holds for length that is a multiple
of 1/2 on the operating frequency.

The fact that the Alpha antenna you linked to is only 75' long should make it clear that it is not in this
category, especially on 80m and 160m.  (With a 50' "radiator" and 25' of "feedline", it would act as a J-pole
only around 9.3 MHz.)


A second type of end-fed antenna is a some-what random length of wire fed through a wide-band transformer
at the base.  There are a number of variants, and instructions for building your own are available on the internet.
Most versions still require an additional tuner, and rely on the coax acting as part of the antenna (so of course
you are likely to have problems with RF in the shack in many installations.)


An end-fed wire antenna of sufficient length (not too short, and too long has its own problems) fed against
a good RF ground system using a tuner at the feedpoint can be a very effective antenna when proper attention
is paid to the radiation patterns from the wire.  I've used several of them over the years with good results
while operating QRP.  The problems typically appear when there isn't a good ground, a length of unsuitable
feedline is used between the antenna and the tuner, and/or a single simple matching system is pressed into
service over a very wide frequency range.

That's not to say that the various sorts of less-than-optimum end-fed antennas won't radiate RF and allow
you to make contacts:  they probably will, at least on some bands.  As Les Moxon, G6XN, said about one
method for end-feeding a wire, "While it isn't a good way to get a wire to radiate, it isn't a good way to
keep it from radiating, either."

 28 
 on: Today at 08:57:23 AM 
Started by N3DT - Last post by K7KBN
As K6AER suggested in reply #1, check things out with the chassis removed from the enclosure.  Do this in a pretty dark room so if anything's arcing you'll be able to see the little bit of light.  As with any high voltage situation, be extremely careful and only use ONE hand.

 29 
 on: Today at 08:56:04 AM 
Started by WD4ELG - Last post by K4SAV
In 2003 I was one of the principal engineers at Sprint. We (my group) were task with the evaluation of brushes, fuzz balls or brooms in their ability to dissipate lightning strikes. We attached these lightning dissipaters to 50 towers in the Orlando area and attached lighting strike indicators to the tops of the towers.

I wondered why all those porcupines went up.  Now I know.

Let's see -- 50 towers, 2345 strikes, that's 46.9 strikes per year on each tower.  It doesn't surprise me.  I lived there 38 years.

Jerry, K4SAV

 30 
 on: Today at 08:50:42 AM 
Started by W2BLC - Last post by W8JX
500 watts is worthwhile, but 800 is better. Whether it's worth the cost depends on the cost!


800 is a good number and adds 9db. Going from there to legal limit adds only 3 db more. 

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