Talking house, changed antenna?

The Talking House/I AM Transmitter was designed to use either an 8 foot piece of wire with the internal auto-tuner or the remote antenna unit called the ATU.

It would seem the remote antenna unit has disappeared from their website.  The ATU consisted of a manual antenna tuner and RF peaking meter.  A standard 102" whip antenna was attached to the ATU.  The ATU was connected to the transmitter with a length of coax allowing the transmitter to remain inside the house.

The "system" to include the use of the ATU was certified by the FCC for Part 15 use.  Typically the "system" was supplied with 25 feet of coax and was stated up to 300 feet of coax could be used.

Lately the website shows the Talking House/I AM Radio transmitter mounted in an outdoor box with the whip antenna attached to the box.  As such, the internal auto-tuner matches the antenna to the selected frequency.

I emailed and called to inquire about the ATU but never received any response.

There was always a great deal of controversy regarding the use of the ATU when elevated.

Very helpful, thanks.  I went looking for the atu also, and didn't find any.  I don't think the realty people needed them.  I'm thinking an antenna like the one sstran has plans for might be interesting, sitting over ground radials or at least a grounding rod.

I've been using a Talking House transmitter with the ATU for several years.  It is a simple to use antenna system which works fairly well.

My ATU/antenna is mounted on the house, above the TV antenna.  There is no separate ground wire attached.  The coax is about 35 feet long.

When using the wire antenna and internal tuner the range is very limited, about 300 feet.  With the ATU the signal is very good at 1/2 mile and can be heard about 1 mile.

The controversy mentioned regarding elevated installations of the ATU is due to the fact that the coax shield may radiate.  The difference over interpretation of the FCC certification regarding elevated installation was never resolved as complete OET certification information was not available detailing how the ATU could be installed.

The new Talking House Outdoor unit has had me head shaking for months.

http://sales.talkinghouse.com/shop/item.aspx?itemid=46
$595 for a TH unit, a cheap outdoor box, a run of coax and a whip antenna?!?!?!?

I am beginning to think the i.AM radio folks are reading Part15.us archives.  I asked about direct tethering a TH unit to a whip antenna using a very short piece of coax a while back.

I did exactly this and the unit tunes.   That transmitter likely based on location never performed well.   About to revisit that project soon though.  i.AM doing literally the same thing with a bit more clean connector setup, meh. Unimpressed.

Still wondering why they pulled the proper ATU unit.  Then again, they want $295 for a simple old TH indoor unit.

I recently emailed their sales people again to request info about the ATU as it is no longer on the website.  Still no reply after a week.

I guess they don't want to bring up the subject.

all the hoopla about the possible legal grey area concerning the ATU being connected by a piece of RG6 longer than 3 meters including whip antenna, ground and coax is the real reason i believe that they discontinued the ATU.

Well, has anyone ever tested the coax betwen the TH indoors unit to the ATU?  Determined if it is radiating back indoors or providing any other benefit?

I was reading some TH patent docs I think MRAM dug up.  Which had me off reading the ATU docmentation.

First off, the ATU bundled an antenna that was 96 inches, not the 102 inches we normally all use. Seems sub-optimal.

Second, page 2, diagram shows a wall mount install of the ATU, with the tip of the antenna bearly poking above the structure it is directly mounted on (which would be mega bad placement and create all sorts of signal weirdness).

Third, they say the higher you mount the antenna, the further the signal will go.  This is AM radio folks.  There is some truth to getting above obstructions like power lines and trees, but yeah, AM and height have a relationship where you also have proper tower with ground and not doinking around with this 3 meter rule.

Fouth, on page 5 of the ATU manual, they mount the ATU to a piece of outdoor lumber directly on a brick faced structure.  The antenna on this installation is at the tip and downward fully backgrounded by brick.

Fifth, the ATU bundled 100 ft of coax, so if that isn't being choked to make it part of the antenna, then yes, very out of compliance and bad.

Sixth, they give grounding recommendations on the last page, which includes "the center screw that holds the cover on a wall electrical outlet".  Why they recommend bringing outdoor run into home electrical like this or even a building is simply stupid.  They do mention two other options thereafter - plumbing pipes and copper grounding rods driven into earth.  The grounding rods are all anyone should be doing with the ATU, unless they lack soil access.

I can say after looking at the design that the shield of the coax is tied to the ground lug. So I guess if mounted high, one could take advantage of the shield radiating.

The TH ATU continues to be the step child that somehow snuck through FCC certification, no? 🙂  If it works well enough, I'll be looking for more of these 🙂

@wdcx, what did you look at design wise to see the sheld of the coax being tied to the ground lug?  Just so others see the same 🙂

Unsure how I am mounting this ATU when all is said and done.  I have soil that is no help / bad for broadcasting.  I also have high power wires on 3 sides and the 4th side has actual run from the power pole to building electric meter.  Plus getting above the power lines means going up pretty high, probably in 40-50ft area with the whip antenna kicking up above there.

I'd may be ahh out of compliance per se (with the puritans and a difficult field agent) running that ground to the metal tower structure which is to be in the ground and wire for ground ran to a series of copper grounding rods.  But, that my friends is what I'll probably test first, as that is mostly if not entirely what the unit was described to be installed.  Of course I am printing the ATU docs out and shoving in a folder and playing along 100% and keeping on shelf for easy future reference.

Myself, I feel more comfortable using an in-line coax lightning/surge arrestor and no separate ground.  You'd want one anyway to try to stop it in the coax outside the building to protect the transmitter.  And, since the coax shield is electrically connected to the same ground lug it should work as well.

The manufacturer emphatically states it is accepted per the certification to use coax of any length.  But, they state that using a separate ground wire will put it out of compliance depending upon the length of the resulting ground path.

The Talking House ATU schematic does show the coax shield and ground lug tied together.  That schematic is available HERE.

I feel more comfortable using an in-line coax lightning/surge arrestor and no separate ground. 

Wouldn't an issue with this concept be that per the schematic posted, an "in-line coax lightning/surge arrestor" does ~nothing to reduce the radiation from the outside surface of the outer conductor of a TH-type, coax-driven, external, elevated ATU+antenna system except (perhaps) for a few milliseconds during nearby lightning surges?

Otherwise, the outer surface of the outer conductor of that coax cable is free to radiate.

For situations where the external ATU+whip are elevated above the surface of the earth, such a coax-driven antenna system could be non-compliant with FCC §15.219(b) except during those very brief times when nearby lightning surges might prevent it due to use of an effective "lightning/surge arrestor."

Of course people are free to operate as they wish, but hopefully this information might be useful in such decisions.

Thanks @mram1500 ....

Where, in what document did TH state the separate ground would be out of compliance? Just trying to line my birds up, not doubting what they may have said....

The in-line coax lightening / surge arrestor - what do you recommend - make/model?   Going to give that a try or at least have such on hand for field trial day.

I'm not suggesting the system would be compliant whether or not the in-line protector is used.  I'm simply following the FCC OET certification provided which states the ATU was tested with 8 meters of coax and accepted.

My only concern is the safety issue and the fact that the manufacturer states in the user manual and in a letter provided that using a separate ground may present a non-compliant installation.

As for a recommendation, no-too much liability there.  Of course PolyPhasor is one of the industry standards for protectors but anything is better than nothing.  My reason for using an in-line protector is that although using the ground lug may direct some of the surge to ground the coax may direct some of that surge to the transmitter.  Using the in-line protector hopefully would stop that.

At that I suppose its a false sense of security where direct lightning strikes are concerned.

Just to note that most surge suppressors use a device having essentially no affect on system performance, except during times when transient voltages on the protected conductor exceed the flashover voltage of that device -- which can be present on that conductor for several milliseconds during/following a nearby lightning event.

Even then, such effectiveness depends on a very low-impedance path from the "ground" terminal of the surge suppressor itself to the necessary ground plane.

So except for such very brief, transient conditions, a "surge suppressor" does almost nothing to prevent radiation from unfiltered/uncoupled connections to a long conductor connected to the chassis of an elevated "Part 15 AM" transmitter, or from an external ATU to the outer surface of the outer conductor of a coax cable connected there.

BTW -- from what I've seen on line, some of the commercial transmitters sold/used for Part 15 AM already include such transient protectors in their output networks, in the form of gas discharge tubes.