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Confusing RF switch advice fr. Consumer Reports?

post #1 of 14
4/30/08 at 12:08pm
Thread Starter 
So, I have determined that the odds of a pass-through box being in stores near me are practically nill, at least before my coupon expires, so thought about a switch install so I can still get analog.

Found the following on Consumer Reports, but it sounds way more involved than I thought it should be for a TV with only antenna input...

So, do I really need two switches, etc. Here's what CR says:

>>>>For TVs that only have an antenna input connector (no separate video inputs), you'll need both an RF antenna splitter and an antenna A/B switch. The splitter should be connected between the antenna and converter box, with one cable connected to the DTV converter box's RF antenna input, and the other going to one of the inputs on the 2-way A/B switch (effectively bypassing the converter). Then run a cable from the converter box's RF output to the second input on the A/B switch. The A/B box's single output is then connected directly to the TV's RF (cable) antenna input. When the A/B switch is on the "digital" (A) side so it's receiving the converter box's signal, tune your TV to channel 3 or 4 to watch digital programs. When you click the switch to the "analog" (B) setting, you'll be able to view any available analog programs by changing channels on the TV. The downside is that you'll have to manually switch between the two inputs on the A/B switch every time you want to switch from an analog channel to a digital one.<<<<<<<<<<br />
Anyone??
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post #2 of 14
4/30/08 at 12:16pm
Quote:
Originally Posted by mountaintop View Post

So, I have determined that the odds of a pass-through box being in stores near me are practically nill, at least before my coupon expires, so thought about a switch install so I can still get analog.

Found the following on Consumer Reports, but it sounds way more involved than I thought it should be for a TV with only antenna input...

So, do I really need two switches, etc. Here's what CR says:

>>>>For TVs that only have an antenna input connector (no separate video inputs), you'll need both an RF antenna splitter and an antenna A/B switch. The splitter should be connected between the antenna and converter box, with one cable connected to the DTV converter box's RF antenna input, and the other going to one of the inputs on the 2-way A/B switch (effectively bypassing the converter). Then run a cable from the converter box's RF output to the second input on the A/B switch. The A/B box's single output is then connected directly to the TV's RF (cable) antenna input. When the A/B switch is on the "digital" (A) side so it's receiving the converter box's signal, tune your TV to channel 3 or 4 to watch digital programs. When you click the switch to the "analog" (B) setting, you'll be able to view any available analog programs by changing channels on the TV. The downside is that you'll have to manually switch between the two inputs on the A/B switch every time you want to switch from an analog channel to a digital one.<<<<<<<<<<br />
Anyone??

Correct, you'll need two devices...a signal splitter with two RF outs, and an A/B switch, connected in the manner that Consumer Reports is recommending.

The signal splitter is necessary, because it divides your antenna input into two separate outputs, so that you can send the antenna signal to both your digital converter and your TV. The A/B switch is just as necessary, as it allows you to manually select which device you'll be sending to the television--your antenna, or your digital converter.
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post #3 of 14
4/30/08 at 12:48pm
If you have a weak signal from the antenna it is better to put a switch instead of a splitter before the converter box because the splitter will weaken the signal some amount. If the switch is manual then flip both at the same time to the proper position.

Their description was for a splitter and switch, can do the same with two switches.
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post #4 of 14
4/30/08 at 3:36pm
Thread Starter 
Thanks to you both. Since I live in a marginal area for TV reception, I'll go with the switches.

My antenna shop has them in stock.
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post #5 of 14
4/30/08 at 4:13pm
Code:
Sorry for the crappy ASCI Schematic, we can't post pics here..
 
Avoiding the 3-4 Db loss of a splitter with two RF slide switches
 
      Slide Switch One                 Slide Switch Two
      _________________                _________________
      |       _       |   Bypass Link  |       _       |
      |      |@|Out A>|>-------------->|>A In |@|      |
      |      | |      |                |      | |      |
Ant In|>In   | |      |  To      From  |      | |  Out>|To TV
      |      | |      | Conv.    Conv. |      | |      |
      |      |_|Out B>|>---|      |--->|>B In |_|      |
      |_______________|    |      |    |_______________|
                           |      |
                           |      |
                        ___|______|__
                        | In    Out |
                        |           |
                        | Converter |
                        |           |
                        |___________|
 
It helps to mount them inline and connect both the two sliders
with a bar. The horizontal equal symbols are the bar...
 
        Bypass Link
   _______________________
   |                     |
   |                     |
   |   To Box  From Box  |
  ___   ___       ___   ___
  | |   | |       | |   | |
__| |___| |__   __| |___| |__
|  |     |  |   |  |     |  |
|  A     B  |   |  B     A  |
|  Switch 1 |   |  Switch 2 |
| _________ |   | _________ |
| |      @|=|===|=|======@| |
| ~~~~~~~~~ |   | ~~~~~~~~~ |
|        ^  |   |        ^  |
|    In  ^  |   |    Out ^  |
|____ | _^__|   |____ | _^__|
     | | ^           | | ^
     |_| ^           |_| ^
         ^               ^
     Ant ^           TV  ^
         ^               ^
         @===============@
              ^^Bar^^
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post #6 of 14
4/30/08 at 5:09pm
The "code" tag will help, but you'll probably need to edit the text offline in a text editor set to a monospaced font, then paste the whole gob into the message-composition window. Here's my attempt at a tic-tac-toe board:

Code:
+---+---+---+
| X |   |   |
+---+---+---+
| X | O |   |
+---+---+---+
| X |   | O |
+---+---+---+
It looks like crap after pasting into the message-composition window, but it should look OK when posted... yep, it does.
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post #7 of 14
5/1/08 at 8:33am
Quote:
Originally Posted by mountaintop View Post

So, do I really need two switches, etc.

Not if your TV has RCA inputs. Then only one switch is enough.

Radioshack.com has links to some illustrations in .pdf format:

http://rsk.imageg.net/graphics/uc/rs..._bypass_av.pdf
http://rsk.imageg.net/graphics/uc/rs..._bypass_rf.pdf

As others have said, you'll probably be better off with a switch than a splitter upstream of the CECB.  I tried it with both out of curiosity, and the attenuation of a splitter really made a difference on the weaker channels.

Of course those illustrations give a Radio Shack part number for everything, since they want you to buy there rather than buying elsewhere or using what you might already have on hand.
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post #8 of 14
5/1/08 at 10:34am
I agree with the loss, have seem it myself.

Note to others, replace the splitter indicated in both PDF's with a switch.
My diagram above is equal to the second PDF option

Good point about the fact some TV's have RCA in too, only one switch would do in that case.

Beleive it or not I have one of those old TV's that have a pair of converter jacks. Kinda like the equalizer jacks on old stereos. just hook the antenna to the first, and any converter box to the second and third ones and a button on the remote does the switching for you.

The RF out to the converter is dead until you hit ''Pay'' on the remote, so I know they actively switch it (not split it). Sure wish that caught on more...
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post #9 of 14
5/1/08 at 10:42am
Quote:
Originally Posted by WeThePeople View Post


Beleive it or not I have one of those old TV's that have a pair of converter jacks. Kinda like the equalizer jacks on old stereos. just hook the antenna to the first, and any converter box to the second and third ones and a button on the remote does the switching for you.

I still have a Sony Betamax that has the same feature.
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post #10 of 14
5/1/08 at 12:09pm
SEARS just got in the new Maganavox G9 with passthru. I just bought one. It works well
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post #11 of 14
5/1/08 at 10:20pm
Quote:
Originally Posted by lexus2108 View Post

SEARS just got in the new Maganavox G9 with passthru. I just bought one. It works well

Lexus, the Sears stores near here do not have any converter boxes yet.  Whereabout are you located?  (My location is below my name to the left.)
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post #12 of 14
5/3/08 at 4:31pm
The whole world needs these darn things...
Why hasn't a switch manufacture made a switch thats just like
(can even use the same case & buttons)
the current three F-Connector style A/B switch with 1 extra jack.

Scroll up to my blue ASCI schematic above and ask yourself how hard it would be to just put the fourth jack on something existing and add a second layer of switch.

Am I the only one to wonder this?

I'll take names of major players that make switches from people here and take the initiative to ask them to add it to the product line if you'll just take the time to share with me (ONLY) makers of GOOD switches currently.

First one to say RatShack gets slapped...

(For the record Philco, then Allan Bradley used to make their RF switches and they WERE good then...)
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post #13 of 14
5/3/08 at 6:57pm
WtP: if I understand what you're talking about, could the connectors for the intermediate device (it could be used for a whole lot of other things as well) be lengths of coax with male ends?  Of course there would be female jacks for the initial input and final output.

And one toggle handles both halves of the switching, right?
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post #14 of 14
5/3/08 at 8:22pm
yes,
that variation wouldn't be to limiting.

I've made them with two slides inline with both slides connected by a bar as above,
although the bar continues through a hole to a knob as a push/pull arrangement.
(Yacht dashboard...)

I have also done this with two paddle-type RF switches stacked on top each other
and connected like how a pair of 110-VAC breakers make a 220-VAC two pole breaker.

But the paddle switch idea could be realized in one housing.

Two switches in their own cavity, and source/sink resistors for the unused ports
to control load factor properly and reduce crosstalk.

And of course four connectors on the back instead of three.
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