Topband: 2 wire beverage reflection transformer

[w2lk at bk-lk.com]

John,

See:
http://www.elisanet.fi/oh3xr/OH2BEN_Reversible_Beverage_Array-20-10-2007_04d.pdf
for an excellent article on a reversible beverage project.
Also, go to w8ji.com for great detail on beverage antennas.
Search on N1EU for more info on same.

Use the type 73 binocular forms if you have them. The sites above will
tell you why.

You should use a resistor of the impedance value on unused ports.

The reflection transformer hi Z side should match the impedance of the
transmission line (618 ohms in your case) and its center tap goes to the
top side of the lo Z side which should match the antenna impedance (334
ohms in your case). The bottom of the lo Z side goes to ground.

My system is similar to OH2BEN's where the output of T1 and T2 are
switched to a single coax at the transformer in the field. The unused
port has a resistor across it.

Les W2LK


-------- Original Message --------
Subject: Topband: 2 wire beverage reflection transformer
From: "john" <jb at beaumonts.karoo.co.uk>
Date: Mon, October 19, 2009 2:57 pm
To: <topband at contesting.com>

Hil topbanders, 

I wish to construct a 2 wire beverage, I have purchased 2 rolls of 7
strand electric fence wire and have installed the supports at 10ft ht,
Beverage length 800ft

ant wire

Dia 1.5mm
ht 10ft
spacing 12inch

We are on heavy clay ground with quite high water table especially in
winter (not so good for bev!!)

On an excel programme received, calculated imp was T1 - 618 ohms and T2
- 334ohms.

Advice please ie : calculatd guess if you think this is incorrect please
advise.

Transformers 2 stacked MN8CX in bronze clips, as I have already
purchased please advise if binc cores better wire 30 awg or .3mm approx.

My thoughts were:

Using the spreadsheet and calcs T1 primary 3 turns for 50ohm and
secondary 11 turns centre tapped
T2 - 3 turns primary 8 turns secondary tapped 3 turns from cold end.


I do not know the set up for the reflection transformer and would
appreciate advice as there does not seem to be a lot of info info on
reflection transformers.

Need to get info on reflection transformer !! TKS

 I note various methods of termination including 1/4 wave and capacity
hat and coil terminations advice appriciated.

I have previously constructed many single wire beverage antennas with
good earth systems at each end and made note of common mode problems but
have never construted a 2 wire one.

Also when you bring the 2 x feeder into the shack I understand the
unused one should be terminated in characeristic impedance (Value!)

cheers guys

your thoughts / comments please
 
best 73/dx

Regards
John G4EIM (36 WAZ)

_______________________________________________
Topband mailing list
Topband at contesting.com
http://lists.contesting.com/mailman/listinfo/topband