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Cable TV switch box circuit - RF Cafe Forums
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dmac Post subject: Cable TV switch box circuit Posted: Thu Nov 13,
2008 2:57 pm
Lieutenant
Joined: Thu Nov 13, 2008 2:48
pm Posts: 2 I have a control circuit that has TTL electrical
levels (I can change it to some other electrical interface as well if
needed) that I want to drive a switch circuit of some sort to turn "on"
and "off" a simple, inexpensive switch, relay, or whatever makes sense
to use for Cable TV signal. Basically, picture the cable TV signal coming
in to a house (standard RG59 F type connector), going into this box
and the cable going out of the box to my house cabling for the TV sets.
So, the big question is what do you suggest I use for a switch that
I can put on a PCB. I will do the PCB design myself, but should I use
an analog switch, RF switch, Relay, or what? What makes sense. I can
put the F type connectors on the PCB that route traces to this switch,
relay or whatever makes sense.
Thanks, Dmac
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markapexwireless Post subject: Posted: Tue Nov 18, 2008
3:42 pm
Captain
Joined: Tue Jul 08, 2008 7:15 pm Posts:
11 Location: Boulder Colorado DMAC,
I would try high
power RF switch such as UPG-2010 from NEC/CEL. You can probably get
eval board from NEC to test this out using SMA/F adapters. Only concern
is if your cable company is running DC through the cable to power up
amplifiers upstream. You can probably test this by putting a DC block
(broadband capacitor) in your cable and see if you still get the signal.
If DC is present, you will have to make bypass, which will be more complex.
Good Luck!!
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dmac Post subject: Posted:
Wed Nov 19, 2008 9:55 am
Lieutenant
Joined: Thu Nov 13,
2008 2:48 pm Posts: 2 Understood, but what about just using an
electro-mechanical relay that will handle the bandwidth of the cable?
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markapexwireless Post subject: Posted: Wed Nov
19, 2008 2:05 pm
Captain
Joined: Tue Jul 08, 2008 7:15
pm Posts: 11 Location: Boulder Colorado DMAC,
Relay
should work fine, as long as it is "coaxial" RF relay. You will probably
need a power supply of some sort to supply current to coil, whereas
with FET switch, a battery would last for quite some time.
You
might check on e-bay to see if someone has used RF relay, possibly extracted
from a piece of RF test equipment.
Good Luck!!
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IR Post subject: Posted: Sat Nov 22, 2008 2:47 pm
Site Admin
Joined: Mon Jun 27, 2005 2:02 pm Posts:
373 Location: Germany Hello dmac,
Concerning DC which
might appear on the cable: You can use a Bias-T device, which will pass
both the AC (RF) component and the DC component. The Bias-T is made
of a capacitor and an inductor.
You can find one a suitable
one by companies like Minicircuits etc.
Posted 11/12/2012
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