This is a good article. I've often wondered about that ferrite with the
two windings on it.
http://user.netonecom.net/~swordman/...Loops_Fig9.jpg
That is how my RDF antenna is designed. If you look at many of the old
boating RDFs, they use a stereo phone plug/jack as the interface, i.e.
two wire ends plus ground. The ferrite sits in a copper shield.

Untuned loops really make sense if your radio is decent. That is one
reason I like the wellbrook. But this paper has given me a few ideas on
how to use a RDF loop. Incidentally, the ferrite rods from these RDFs
show up occasionally at flea markets. The radio has crapped out, but
someone wisely saved the ferrite. I saw one on sale for $2 at the last
Livermore swap meet.



wrote:
wrote:
The Burhans papers are on vertical whips. They are really noisy for HF.
But the list of papers is impressive.
--------------------------
I can't find the link to a pdf of the entire article, so try:
http://user.netonecom.net/~swordman/Radio/re-loop-article.htm

Terry

wrote:
This is a good article. I've often wondered about that ferrite with the
two windings on it.
http://user.netonecom.net/~swordman/...Loops_Fig9.jpg
That is how my RDF antenna is designed. If you look at many of the old
boating RDFs, they use a stereo phone plug/jack as the interface, i.e.
two wire ends plus ground. The ferrite sits in a copper shield.

Untuned loops really make sense if your radio is decent. That is one
reason I like the wellbrook. But this paper has given me a few ideas on
how to use a RDF loop. Incidentally, the ferrite rods from these RDFs
show up occasionally at flea markets. The radio has crapped out, but
someone wisely saved the ferrite. I saw one on sale for $2 at the last
Livermore swap meet.
++++++++++++++++++++++++++
By using Litz wire and taking some care it is "easy" to get a ~10" X
3/4"
rod to work up to around 10MHz. Above that it goes downhill "real
fast".

I ran into this winding on a dead RCA RDF a friend gave me. I rembered
seeing the article back in Radio Electronics but had completly
forgotten.

Burhans had some designs that were light years a head of their time!

I wish I had payed more attention when they first came out. It was a
royal
PITA to get photocpies from the local university's enginering library
microfilm
editions of Radio Electronics.

Terry

Is the skin effect significant because you are trying to get lots of
windings which implies fine wire? Also, what about spacing between the
wire (i.e. interwinding capacitance)?

One of the papers mentioned the higher permeability cores had lower
bandwidth.

I've been fiddling with multiple turns with the Wellbrook ALA100. I've
got so much signal strength on local BCB that I can hear an internal
relay switching in an attenuating pad.

wrote:
wrote:
This is a good article. I've often wondered about that ferrite with the
two windings on it.
http://user.netonecom.net/~swordman/...Loops_Fig9.jpg
That is how my RDF antenna is designed. If you look at many of the old
boating RDFs, they use a stereo phone plug/jack as the interface, i.e.
two wire ends plus ground. The ferrite sits in a copper shield.

Untuned loops really make sense if your radio is decent. That is one
reason I like the wellbrook. But this paper has given me a few ideas on
how to use a RDF loop. Incidentally, the ferrite rods from these RDFs
show up occasionally at flea markets. The radio has crapped out, but
someone wisely saved the ferrite. I saw one on sale for $2 at the last
Livermore swap meet.
++++++++++++++++++++++++++
By using Litz wire and taking some care it is "easy" to get a ~10" X
3/4"
rod to work up to around 10MHz. Above that it goes downhill "real
fast".

I ran into this winding on a dead RCA RDF a friend gave me. I rembered
seeing the article back in Radio Electronics but had completly
forgotten.

Burhans had some designs that were light years a head of their time!

I wish I had payed more attention when they first came out. It was a
royal
PITA to get photocpies from the local university's enginering library
microfilm
editions of Radio Electronics.

Terry