I am attempting to build a T2FD antenna for use on the 20 through 10 meter
ham bands with my new Ten-Tec Argonaut V transceiver. While not a part of
the issue my wife of almost 40 years has ordered the Argonaut V for me for
Christmas.

Well, back to the issue at hand:

The design requires a 6:1 ratio broadband transformer to match 50 ohm cable
to the impeance of the antenna. I have not been able to find any simple
construction data for a 6:1 (50 - 300 ohm) transformer that would work well
over the 14 - 30 mHz frequency range. I would appreciate it if someone
would point me to some practical construction data for such a transformer.
The design power would be 100 watts.

The entire antenna can be purchased from B&W but $199 seems awfully pricey.

73 - Mike - K9JRI

Hi Mike

Funny - I am doing almost the same thing. Mine is based on the cebik data
(http://www.cebik.com/wbfd.html) on T2FD's that covers 80-10M. (You may
have heard that Oz limited call amateurs get HF on Jan 1...)

His calls for an 800r termination and hence a 800r feedpoint with a 16:1
balun. I have just purchased the toroid (F25 material from Neosid - about
35mm OD, 17mm thick) and am working out the winding details. Someone told
me that you work on the primary side XL being 10x the source Z (ie 500r -
about 8 turns) but I havent been able to clarify which end or whether the
middle freq was being talked about. I actually intend working through a
document on it this weekend (lack of good weather permiting)

Oh yeah the turns ration is a square/Z function. ie 4x the turns ratio = 16X
the Z.

This size toroid seems to be about anecdotally correct for 100W. I seem to
remember 40mm being able to handle 400W. Higher powers you need to consider
arcing between turns and to the ferrite itself. Some rings come with teflon
like insulation for just that reason. I am just going to wrap mine in tape
and hang it from the feedpoint! If the tape discolours from heat I'll do
something about it

The terminating resistor needs to be non inductive and be able to dissipate
half the TX power. I actually wonder that given the broad nature of the
antenna whether the non-inductance is so critical. YMMV!

I'll repost as I get more toroid details. Oh BTW they were all of about AUD4
each!

Cheers Bob VK2YQA

I am attempting to build a T2FD antenna for use on the 20 through 10 meter
ham bands with my new Ten-Tec Argonaut V transceiver. While not a part of
the issue my wife of almost 40 years has ordered the Argonaut V for me for
Christmas.

Well, back to the issue at hand:

The design requires a 6:1 ratio broadband transformer to match 50 ohm
cable
to the impeance of the antenna. I have not been able to find any simple
construction data for a 6:1 (50 - 300 ohm) transformer that would work
well
over the 14 - 30 mHz frequency range. I would appreciate it if someone
would point me to some practical construction data for such a transformer.
The design power would be 100 watts.

The entire antenna can be purchased from B&W but $199 seems awfully
pricey.

73 - Mike - K9JRI

--


(The reply address is broken. Put bcnoop in front of the at!)

Mike,

You can get 6:1 baluns from Amidon. go to
http://www.amidoncorp.com/aai_hampricing.htm#
and click on baluns.

Tam/WB2TT
"Mike Blake" wrote in message
gy.com...
I am attempting to build a T2FD antenna for use on the 20 through 10 meter
ham bands with my new Ten-Tec Argonaut V transceiver. While not a part of
the issue my wife of almost 40 years has ordered the Argonaut V for me for
Christmas.

Well, back to the issue at hand:

The design requires a 6:1 ratio broadband transformer to match 50 ohm
cable
to the impeance of the antenna. I have not been able to find any simple
construction data for a 6:1 (50 - 300 ohm) transformer that would work
well
over the 14 - 30 mHz frequency range. I would appreciate it if someone
would point me to some practical construction data for such a transformer.
The design power would be 100 watts.

The entire antenna can be purchased from B&W but $199 seems awfully
pricey.

73 - Mike - K9JRI

Try this one for the toroid Mike

http://www.electronics-tutorials.com...ansformers.htm

Cheers Bob VK2YQA


Funny - I am doing almost the same thing. Mine is based on the cebik data
(http://www.cebik.com/wbfd.html) on T2FD's that covers 80-10M. (You may
have heard that Oz limited call amateurs get HF on Jan 1...)

His calls for an 800r termination and hence a 800r feedpoint with a 16:1
balun. I have just purchased the toroid (F25 material from Neosid - about
35mm OD, 17mm thick) and am working out the winding details. Someone told
me that you work on the primary side XL being 10x the source Z (ie 500r -
about 8 turns) but I havent been able to clarify which end or whether the
middle freq was being talked about. I actually intend working through a
document on it this weekend (lack of good weather permiting)



(The reply address is broken. Put bcnoop in front of the at!)