Convert Twin UHF Coax TV Aerial Socket to a Resistive Splitter

I have just bought a nice screened twin Coax TV aerial socket wall plate
from RS - the actual one is Maxview H87002. I was disappointed to see that
it has 2 separate coax cable inputs. I want to modify it so that it uses
one coax input and arrange a resistive splitter to the 2 sockets so that 2
things can be plugged in from one cable. Maxview do not make such a device
in the same product range. I know I can easily fit 2 resistors into the
screened back panel with a little bit if filing to open up an internal
connecting channel between the 2 sides.

Please can someone tell me the value of the resistors I should use for this.
I am assuming the central core of the coax will go onto the common of the
resistors and the other ends will go to the terminal of each of the 2
sockets. I do not want to filter out the sockets for TV or FM but want the
same signal to be split equally between them.

Thanks

Graham

In message , Graham Brooker
writes
I have just bought a nice screened twin Coax TV aerial socket wall plate
from RS - the actual one is Maxview H87002. I was disappointed to see that
it has 2 separate coax cable inputs. I want to modify it so that it uses
one coax input and arrange a resistive splitter to the 2 sockets so that 2
things can be plugged in from one cable. Maxview do not make such a device
in the same product range. I know I can easily fit 2 resistors into the
screened back panel with a little bit if filing to open up an internal
connecting channel between the 2 sides.

Please can someone tell me the value of the resistors I should use for this.
I am assuming the central core of the coax will go onto the common of the
resistors and the other ends will go to the terminal of each of the 2
sockets. I do not want to filter out the sockets for TV or FM but want the
same signal to be split equally between them.

Thanks

Graham



Star configuration: Three 25 ohm resistors (use 27).
Delta configuration: Three 75 ohm resistors.
Loss of either is 6dB.
http://www.tina.com/course/5wye/wye.htm

To save a dB or so, you can cheat by only using two resistors (say 39 or
47 ohms input to each output). However, the system won't be properly
matched.

The minimum loss will be with no resistors, but the loss won't ever be
less than about 3.6dB (assuming each output is terminated in 75 ohms
(which a TV set probably won't be). However, under certain conditions,
one output feed could kill the RF output at the other. Less chance of
this if you do it properly.
Ian.

--

....snip...
Star configuration: Three 25 ohm resistors (use 27).
Delta configuration: Three 75 ohm resistors.
Loss of either is 6dB.
http://www.tina.com/course/5wye/wye.htm

To save a dB or so, you can cheat by only using two resistors (say 39 or
47 ohms input to each output). However, the system won't be properly
matched.

The minimum loss will be with no resistors, but the loss won't ever be
less than about 3.6dB (assuming each output is terminated in 75 ohms
(which a TV set probably won't be). However, under certain conditions, one
output feed could kill the RF output at the other. Less chance of this if
you do it properly.
Ian.


Is there an easy answer to why either is better than a 75ohm in series with
each output, i.e. two legs of the delta? It also looks to me like the star
should somehow give better results as the voltage across each TV should be
75/(75 + 25 + 25) x input as opposed to the delta (and my variant) where the
voltage should be exactly half-input.

However according to your web link, the two circuits should be identical so
I'm now confused!

Paul DS.

Antiference make the proper job "W720"
Although it is not screened, it has an inductive splitter built in
which is better with lower loss and more isolation between outputs.
Hope this helps.
Dave