Building a T2FD antenna
 

David G. Nagel wrote:
The resistors need to be carbon non inductive high wattage.

I have some 50 watt, 600 ohm, non-inductive
resistors removed from a military surplus
antenna tuner.
--
73, Cecil http://www.w5dxp.com

Building a T2FD antenna
 

Cecil Moore wrote:

...
I have some 50 watt, 600 ohm, non-inductive
resistors removed from a military surplus
antenna tuner.

Cecil:

Welcome back.

In your absence, posters to pick on have been sparse. ;-) Those here
for jest and ridicule have been hard pressed ...

Regards,
JS

Building a T2FD antenna
 

John Smith I wrote:

Robert Smits wrote:

...
The article suggests that 24 270 ohm 2W carbon film resistors, wired into
four lines of six resistors in series, and then paralleled would produce
a final resistance value of 405 ohms, and would allow 300 watts on SSB.

Hope this adds to the discussion.

Bob, VE7HS

Hmmmm ...

Any suggestions for a method for dumping the heat from the resistors
back into the shack in the wintertime? :-)

And heck, during the winter, wouldn't it be nice to have the resistors
overall rating able to dissipate a KW and provide more heat?

Regards,
JS

Since the amount of heat dissipated in the resistors will only be 30-40
watts when running 300 watts SSB output, and since they're halfway up the
antenna, I doubt very much that you'd get much heat output.

It's easy to up the wattage rating, but it costs $ to get high wattage
non-inductive resistors.

Building a T2FD antenna
 

Robert Smits wrote:

...
Since the amount of heat dissipated in the resistors will only be 30-40
watts when running 300 watts SSB output, and since they're halfway up the

Ohhh, well, that certainly changes everything, doesn't it?

How about just constructing the antenna out of ni-chrome wire, that way
it will be self-defrosting?

Regards,
JS

Building a T2FD antenna
 

John Smith I wrote:

Robert Smits wrote:

...
Since the amount of heat dissipated in the resistors will only be 30-40
watts when running 300 watts SSB output, and since they're halfway up the

Ohhh, well, that certainly changes everything, doesn't it?

How about just constructing the antenna out of ni-chrome wire, that way
it will be self-defrosting?

Regards,
JS

Nah, that's totally unnecessary. Given the amount of hot air generated by
the average ham conversation, anyway. :-) :-)

__|
Robert Smits _/. |\
(VE7HS) CQ CQ CQ !!! (0)
_ /__ |
( ) _______/
\ \/ \__

Building a T2FD antenna
 

On Thu, 09 Aug 2007 16:13:28 -0700, Jim Lux wrote:

David G. Nagel wrote:
Rick (W-A-one-R-K-T) wrote:

snip
Or those nice inexpensive Caddock non-inductive resistors available from
Mouser for about $2 each for the low power versions, up to $10 each for
the higher power ones.

http://www.mouser.com/catalog/631/552.pdf

http://www.caddock.com/Online_catalo...000_Series.pdf


available up to 100W rating (assuming bolted to an appropriate heatsink).
I'd string together a bunch of an appropriate resistance, either series or
parallel, your preference.


I used one of those resistors (sold as motor shunt resistors) for my
antenna and constructed a small 5" by 5" heat sink that flys with the
antenna. The commercial balun, ($80USD) which was a bit heavy to mount on
the antenna was mounted on a fence post underneath the antenna. I
constructed some 450ohm balanced line to go between the balun and antenna.

pics:
http://vambo.org/pictures/antenna/

This antenna has been the greatest thing I've ever done to improve my
Hobie. This antenna is about 8 years old and has survived a move to a new
QTH.