Dual Purpose Antenna

[thoer]

After reading a bit about TV and FM/AM antennas, it seems to me that the same antenna on the roof of an Escape could serve for both a TV and a radio/stereo. I've been looking at this model :1byone Omni as it is lists all the required frequencies in its specs. It also comes with a 12V signal amp. My thinking is that the single coax would run from the antenna to its booster amp, then to a splitter. Then one regular coax to the TV and one adapter cable like this one: Adapter cable going to the automotive type radio's ETI uses. The gain of this antenna seems like it should be good, at least to my non-expert reading.

Do any of those of you with more radio/antenna expertise see potential problems I might be missing? I hate to put any extra holes in the beautiful fiberglass roof of our trailers and this seems like a way to use one hole for both systems.

[freespirit]

pretty similar to the Lava RVHD-2015
lavasat.com
lavasat.com/en/upload/proimg/RVHD-2015_Manual.pdf
there is a a wiring diagram there for that version and there appears to be several variations of this antenna on the web all coming from china.
have no idea how good they are....they all seem to be about 12vdc @ 50 ma which doesn't draw much battery power.
The booster amp is probably inside the antenna..the only real difference being the mounting variations, coaxial attachment, and the power injection interface.

[Brian B-P]

Yes, FM radio runs in VHF Band II, which is right between the VHF Band I used for TV channels 1 through 6, and VHF Band III used for TV channels 7 through 13. That means any antenna suited for VHF TV channels is sized right for FM radio as well. There's more to antenna design than frequency, but FM radio and VHF TV are compatible.

Many antennas are sold for this combined use, so they're obviously suitable. You might find some antennas (particularly with amplifiers) which include filters to exclude the bands that are not wanted, so a dedicated TV antenna might not work properly for radio, or vice versa... but the description should say so if this is the case. The 1byone model linked is certainly suitable for both FM and TV.

I would be cautious about the claimed gain. A directional antenna has gain because it is "focused" in one direction, at the expense of all other directions, which is good. This is "omnidirectional", meaning not directional, so it doesn't have this sort of gain - it isn't pointed anywhere in particular, just at the horizon all the way around. They're listing the boost of the amplifier. Amplifying random noise doesn't create useful signal (despite what scriptwriters for TV shows apparently think), so that gain number doesn't say anything about how well the antenna works.

A proper splitter shares the signal strength between two outputs, so both radio and TV will get a weaker signal than if they were not sharing. A better approach is probably to use a separator/coupler, which essentially directs FM radio frequency signal to the radio output, and the rest to the TV output, so both are only slightly reduced from having their own antenna. An example is the Winegard CA8800 FM Band Separator/Coupler FM Tap (CA8800), but this particular product appears to have been discontinued a couple of years ago and so is likely not available: it is listed on Amazon.com, but shows as unavailable. It looks like there are alternatives, but they're hard to find...
1 Ghz TV/FM Isolator; Philmore # CS200

[thoer]

Brian does an ordinary splitter halve the signal strength when only one, TV or radio, is powered on and operating; or always?

Also, with digital HD TV broadcast signals becoming more common, wouldn't a booster work better on a weak digital than an analog one? I'm not sure about Canada, but here in the US all the TV over the air signals are digital now.

[Brian B-P]

Originally Posted by thoer

Brian does an ordinary splitter halve the signal strength when only one, TV or radio, is powered on and operating; or always?

Unfortunately, always. Each output is 4 dB lower than the input, which is half power... regardless of whether or not something is using the signal.

If you only want to use one at a time - and unless you are recording from one of them that makes sense - then you could use a switch instead of a splitter. With a switch, whatever is selected would get an undiminished signal. Some time ago these were common, intended as an antenna/cable switch to choose between sources for an analog TV, and you can still get them... but be sure it has the desired connectors (probably F-type) and is intended for the desired impedance (75 ohms as used with TV gear, not 50 ohms as used with most other radio gear).

[thoer]

Thanks Brian - yep I remember those splitter switches, cause I'm old!

[Donna D.]

Originally Posted by thoer

Thanks Brian - yep I remember those splitter switches, cause I'm old!

You mean... an A/B switch?

[Mike Lewis]

I have an amplified home TV antenna, a Channel Master SmarTenna 3000A. It works okay, but it has an FM trap that attenuates (blocks) the FM radio band 88-108 MHz. So be careful when buying an antenna for both TV and FM radio use.

[Brian B-P]

Originally Posted by Donna D.

You mean... an A/B switch?

Yep, but the ones you can find at a reasonable price that are actually suitable (not an audio switch, for instance) are likely to say "cable/antenna".

Originally Posted by Mike Lewis

I have an amplified home TV antenna, a Channel Master SmarTenna 3000A. It works okay, but it has an FM trap that attenuates (blocks) the FM radio band 88-108 MHz. So be careful when buying an antenna for both TV and FM radio use.

I agree. That's what this was about:

Originally Posted by Brian B-P

You might find some antennas (particularly with amplifiers) which include filters to exclude the bands that are not wanted, so a dedicated TV antenna might not work properly for radio, or vice versa... but the description should say so if this is the case.

That Channel Master's Amazon listing doesn't say it won't work for FM radio, but at least it clearly says HDTV (which is just "TV", as far as an antenna is concerned). Channel Master's own page for the CM-3000HD (same antenna?) refers only to TV.

[thoer]

The 1byone vender replied to me and sent along the attached pdf. It shows 2 cables coming from the antenna, one for radio and one for TV. They also include connectors and plates that allow a cable TV connection. With the external cable connection ETI offers, to my inexpert eyes, this appears to be an ideal solution to radio/over the air TV/cable TV connections for an Escape.

Currently the vendor only sells thru Amazon US, but I asked if they could make it available thru Amazon Canada so that I could have it shipped directly to ETI.

[Mike Lewis]

Originally Posted by Brian B-P

That Channel Master's Amazon listing doesn't say it won't work for FM radio, but at least it clearly says HDTV (which is just "TV", as far as an antenna is concerned). Channel Master's own page for the CM-3000HD (same antenna?) refers only to TV.

The Channel Master 3000A, the one I have at home, has been discontinued. From its manual:

SPECIFICATIONS
Bandpass: 54-806 MHz
FM trap (fixed): Attenuates 88-108 MHz
Amplifier gain: 20 dB
Impedance: 75 Ohm unbalanced
Power required: 117 VAC 60 Hz, 4 watts
Weatherproof housing: UV protected copolymer
Mounting type: Round mast up to 1¹⁄₂” O.D.

I wanted to buy a second one for my trailer but I ended up buying a Hulu amplified antenna instead. In retrospect it was probably a bad idea buying a home antenna for the trailer-- I think the Hulu has quit on me, probably due to the vibrations it encountered from travel.

[Brian B-P]

Originally Posted by thoer

The 1byone vender replied to me and sent along the attached pdf. It shows 2 cables coming from the antenna, one for radio and one for TV.

Nice - they built in a splitter for you! They also used a different connector on the radio output, assuming you would want it rather than an F-connector.

Originally Posted by thoer

They also include connectors and plates that allow a cable TV connection. With the external cable connection ETI offers, to my inexpert eyes, this appears to be an ideal solution to radio/over the air TV/cable TV connections for an Escape.

They also threw in a Cable/Antenna switch
They also show a satellite dish, presumably just so you can have a connector for the cable to a dish in the same box and faceplate as the antenna and cable connections.

This does look like it has everything you need.

[MimStan]

Someone commented on Amazon that this switch will work "backwards" - in other words it will act as a splitter of sorts, but without the associated losses:

Steren 200-315 Push Button A/B Switch (200-315) from Solid Signal

[Brian B-P]

Originally Posted by MimStan

Someone commented on Amazon that this switch will work "backwards" - in other words it will act as a splitter of sorts, but without the associated losses:

Steren 200-315 Push Button A/B Switch (200-315) from Solid Signal

Good find of an inexpensive switch. Yes, because it is just a mechanical switch it doesn't matter whether you are sending one input to a choice of two outputs, or selecting between two inputs to a single output.

It's a switch, not a splitter, so you don't get signal to both TV and radio at the same time, but I agree there's essentially no signal loss.

Just for Donna, the button as labelled "A" and "B" and described as an "A/B Switch"... although the device is labelled as an "Antenna/Cable Switch".

It isn't needed with the 1byone, because that antenna comes with both an internal splitter and an external switch, but would work fine for antennas that don't come with these features.

[thoer]

In case anyone else is interested, I received this reply "1byone will sell items on Amazon Canada on May 20, you can buy this item at that time." I'm currently planning on buying one then and having it shipped directly to ETI.

[Brian B-P]

Originally Posted by thoer

Currently the vendor only sells thru Amazon US, but I asked if they could make it available thru Amazon Canada so that I could have it shipped directly to ETI.

Originally Posted by thoer

In case anyone else is interested, I received this reply "1byone will sell items on Amazon Canada on May 20, you can buy this item at that time." I'm currently planning on buying one then and having it shipped directly to ETI.

Well done I'm impressed!