On Thu, 7 Oct 2004 18:59:28 -0700 "Michael Tope" <W4EF@dellroy.com>
writes:
> Hi Marv,
>
> Is the configuration you are speaking of the one that is so commonly
> used in CATV "tap" couplers (I don't have the Sabin book here)?
> That configuration can be easily made to produce flat coupling and good
> directivity over two decades of bandwidth. I have always been surprised
> that this circuit doesn't appear much in amateur literature. It is very
> simple to build.
>
> 73 de Mike, W4EF...................................
>
>Hello Marv,
>
>this sounds very interesting. I have bought an old book from the ex DDR
(Y2)
>army, where I found a description of a coupler without C's. May be it's
the
>same.
>
>Thanks for reply!
>
>Tom, DJ5RE
Hi Mike & Tom,
Perhaps...
Visualizing the thing as a 4 port device.
Port 1 is the RF input
Port 2 is the RF output
Port 3 is the Forward sample
Port 4 is the Reverse sample
Two identical transformers with 32 turn secondaries (for -30 db
coupling) are employed.
The single "turn" primary of the first transformer is connected
between Ports 1 & 4.
The secondary of the first transformer is connected between ground &
Port 3.
The single "turn" primary of the second transformer is connected
between Ports 3 & 4.
The secondary of the second transformer is connected between ground &
Port 2.
Phasing of the windings is consistent with the connection order
detailed above.
For cable TV use, I suppose the reverse port is terminated (w/ 75
ohms?) to make a 3 port critter.
For 50 ohm power measurement, the sample ports need to be terminated
in 50 ohms non-inductive of suitable power rating. A rectification of
this sample may be used to drive a meter or other indicator.
73 & Good afternoon,
Marv WC6W
*
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