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Connecting Digital Converter Box to an old TV

Discussion in 'Electronic Basics' started by Rattler, Dec 8, 2008.

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  1. Rattler

    Rattler Guest

    I admit it, I don't get it. Digitally illiterate. I don't know the
    difference between an ohm and a mho.

    I have this TV I bought in 1975, RCA XL-100. Still works, why junk it?
    Uses a remote control that operates on no batteries, just ultrasound,
    I think. Cool.

    So, I bought a Tivax STB-T8 Digital converter, has analog passthrough,
    a transient benefit, I am told.

    The various and several connections on the back of my old TV looks
    nothing like the drawings-for-dummies in the pamphlet that came with
    the Tivax. I don't know what connects to what. There are coax
    connectors, wire connectors, etc.

    I took pics of the back of my TV and also the back of the Tivax.

    Is there anyone to whom I can email these pics and you could tell me
    what connects to what? For all I know, I may need yet another
    converter box to allow the Tivax to connect to my TV!

    Um, thanks!
  2. Jamie

    Jamie Guest

    It's very easy in your case.

    You should have a F-connector, it looks like an antenna coaxial
    type connector that is round with a center pin that has threads on it.

    one should be labeled as Antenna/Cable box maybe, and the other as
    This device must be connected between your existing antenna coax
    that you have now.
    So, your existing Antenna/Cable wire goes to the Input of this box
    and the output of this box goes back to the TV antenna connection.

    Unless you got your self one of those that has component/HD output
    only!. you may be in trouble! :)"
  3. Rich Webb

    Rich Webb Guest

    I'm guessing that the RCA TV doesn't have coax antenna/RF inputs. What
    you'll need is a "balun" to convert the RF-out from the converter box to
    the 300 ohm antenna connection on the back of the TV. (Balun is just a
    contraction of "balanced-to-unbalanced," balanced twin lead to
    unbalanced coax.)

    Here's an example
    (although I know nothing about that site, other than their link was near
    the top on the search engine).

    Since your antenna is also 300 ohm twin-lead, you'll need a second balun
    to connect it to the converter box.
    ( ) Antenna
    \=== [balun] --- [converter box] --- [balun] === [TV]

    where === is the twin-lead and --- is coax or a coax connector.

    Baluns come with several different types of connector on the coax side.
    You'll almost certainly want one with an "F connector."

    When you're hooked up, tune the TV to channel 3 (the usual default) and
    turn on the coverter box. You should see the intoductory menu.

    For the antenna, almost all DTV is up in the UHF band, so you do not use
    rabbit ears. Use a loop or bowtie antenna. An outdoor UHF is better but
    you'll probably get *something* (maybe everything) with an indoor

    Go to for antenna advice and
    to for info on who in your area is broadcasting
    DTV, the expected signal strength, and where to point your antenna.
  4. Rattler

    Rattler Guest

    I had assumed pics might spare you a lot of typing, so thanks for
    this, each of you!

    Let me describe my TV connections and see if it causes you to fine-
    tune your answer any...

    My TV has built-in twin telescoping antennae. There is no external
    antenna connected. The back of my TV has this:

    A coax cable approx 4 inches long, with a male connector, comes out of
    my TV set through a hole marked "75 ohn VHF Tuner Input". Nearby is a
    female coax connector marked "75 ohm OUT" above it. The 4-inch male
    coax is connected to the female connector.

    Below the female coax connector are two screw-down connections marked
    "VHF ANTENNA". Two 3-inch wires with U-ends come out of the back of
    the plastic TV frame nearby, thru unmarked holes, and connect to these
    VHF screw-downs.
    Labeled between the VHF screw-downs and the female coax connector are
    the words "300 ohm INPUT" so I don't know if it refers to the coax
    connector above it or the screw-downs below it.

    Next to the VHF screw-downs are two more screw-downs marked "UHF
    ANTENNA". Nothing attached to them.

    You mentioned a bowtie UHF Antenna. Yes, there is one, seemingly
    permanently affixed to the back of the set, with wire leads with U-
    ends, unattached to anything. So that's what that is! You know, I
    don't think that UHF antenna has ever been hooked up to the screw-
    downs in the 32 years I've had this TV! LOL!

    The Tivax has RF-In coax jack, RF-Out coax jack, chan 3/4 switch, and
    some type of RJ+++ jack (like telephones have) labeled "Smart Ant. I/

    Does the above information change your detailed prescription any?

    Will the connection of a smart antenna change your prescription any?


  5. Rich Webb

    Rich Webb Guest

    Pictures are always handy, but you may want to consider uploading them
    to a free media server and then posting the link, rather than e-mailing
    them individually. I've used Imageshack for a few
    odds and ends and can attest that it "works" and is genuinely free.
    As Michael said, this is the place. You'll probably need a "bullet" (a
    female to female F connector) to mate between the cable from the
    converter box and the male end of your input cable.
    That's the antenna you'll need to feed the converter box input. If it's
    really a permanent fixture you may want to get a set-top antenna so that
    you can aim it to peak the reception. Some set-top antennas (nowadays,
    maybe most) have coax cables. If you get one that doesn't, or if you
    decide to try the built-in bowtie, you'll need one of those balun
    The smart antenna interface can optionally be connected to an antenna
    rotor to slew the antenna azimuth based on the selected channel. The
    TVFool link above will show you where the digital broadcast towers are
    in your region. If the stations you want are clustered near one bearing
    (or if you're using an indoor antenna and can get up to tweak it) you
    won't need a "smart" antenna. You won't *need* one otherwise providing
    the signal strengths are otherwise okay.
  6. Rich Grise

    Rich Grise Guest

    Why not just take off the 4" pece, and connect the cable right to the
    female on the box?

  7. Rattler

    Rattler Guest

    I dunno!

    However, thanks everyone for the info. I uploaded a pic to Image Shack
    (thanks, Mr. Webb) so let's see if I did THAT correctly. I'll show two
    different links for the same image to see which one works:

    P.S. The TV news just had one more of those ubiquitous commercials for
    DTV conversion. They said you could hook up your converter ahead of
    the deadline. But, isn't that only true if you have a converter with
    analog pass-through?
  8. Rattler

    Rattler Guest

    Why not just take off the 4" pece, and connect the cable right to the
    Wait! I do know! Because it's a shy too short to reach my box when
    placed on top of my TV set?

    Ok, I get this. Looks easy now. I got caught up in the other
    connections on the back of my TV, and the idea that it had to be
    harder because I am not an enguneer. :)

    But, let's see if really get it... how about this... the way my TV is
    configured now, those two wires that come out of the TV case, on the
    left, aren't they simply the leads from my twin telescoping antennae?
    And having them connected as they are to the VHF screw-down inputs
    simply connects them to a built-in balun inside the TV whose output
    appears as the female "75 ohm out" connector? And that is why the
    4"cable had to connect to it, to finally connect the antennae to the
    VHF tuner?

    If yes to all of that, then this cross-connect panel on the back of my
    TV is just a typically inelegant way of going out and in and out and
    in, allowing a choice of connecting to my VHF tuner by either external
    coax cable TV or my internal telescoping antennae? Why I ever got
    confused... well, that's me, expecting, uh, elegance. It is elegant,
    though, for what it is.

    Question: Since my coax tuner input says "VHF", then what tuner do my
    UHF screw-downs connect my bowtie to? A UHF tuner inside my TV,
    perhaps? And, unlike my VHF tuner, this UHF tuner has no option to
    access it via coax?

    My converter box came with a male-male coax jumper. Yeah, I'll need a

    Also, will need a balun for my bowtie. Sounds like a song. ;)
  9. Jasen Betts

    Jasen Betts Guest

    yeah, it is a bit ugly like that.
    yes, the UHF screws go straight to the UHF tuner inside the TV.
    if you want use coax for uhf you need to use a balun.

    the TV has separate UHF and VHF tuner... if you want to use the
    passthrough feature of the converter to use the UHF antenna for analog
    tv the output of the converter needs to be connected to the UHF input
    If the converter box outputs UHF then you'll need to use a balun and
    hook it to the UHF input, if it outputs VHF you can hook it to
    the coax cable (using a bullet coupler)

    if it's outputting VHF the passthrough feature won't be much use.
  10. Rich Webb

    Rich Webb Guest

    Nope. Most (by this time, probably all) stations are broadcasting both
    the conventional analog as well as the digital signals. With the
    converter box hooked up, you should get the DTV.
  11. Mark Zenier

    Mark Zenier Guest

    With the warning that many stations are going to switch from their
    temporary digital channel and put the digital transmission on their old
    analog frequency on the changeover day next February. This will be most
    common on channels 7-13.

    Mark Zenier
    Googleproofaddress(account:mzenier provider:eskimo domain:com)
  12. Rich Grise

    Rich Grise Guest

    Ah! It first sounded like you had a 4" piece of coax plugged into the F
    connector, and the other end just out there flapping in the breeze.

    You need a "bullet" two female Fs back to back, to plug into the end of
    the coax.

    I don't know what comes out of the digital box - you say it has a "3/4"
    switch, like a VCR output? In that case, you'll only need to plug into
    the cable, and disconnect everything from the screw terminals and the
    female F.

    Actually, whenever I find out WHERE to get one of Satan's boxes, I'll
    face practically the same dilemma.

    I wonder if I should start a new thread to ask, "will I need a combiner
    for my existing VHF and UHF antennas? Currently, I have to move the
    cable between the two wheneverI change ranges. But there's a lot of
    overlap - the vhf one goes up to ch. 50 pretty well (It's a wideband
    folded dipole on the roof) and my new 4-bay bowtie (total cost: $2.50
    for the balun) goes all the way down to ch. 7.

  13. Rich Grise

    Rich Grise Guest

    Sorry about that - I just now saw your pix; I had misunderstood about the
    4" piece - I had an image of the end that now goes into the TV was just
    a male F lying out there flapping in the breeze.

    So, never mind. :)

  14. Rich Grise

    Rich Grise Guest

    OK, I've found the coupons; but WHERE IN HELL DO I GET THE DAMN BOX?????

  15. Rattler

    Rattler Guest

    OK, I've found the coupons; but WHERE IN HELL DO I GET THE DAMN

    I belong to so looked at the rating there. Also,
    it explained the options on each model.

    The brick-and-mortar stores in my area carried the same two brands,
    neither I wanted, cost 60-80 bucks.

    I googled and got my Tivax on after coupon
    discount for 15 bucks including shipping. I think the box was 6 bucks
    and the shipping was 9 bucks.
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