• Get involved.
    We want your input!
    Apply for Membership and join the conversations about everything related to broadcasting.

    After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
    If you use a disposable or false email address, your registration will be rejected.

    After your membership is approved, please take a minute to tell us a little bit about yourself.
    https://www.radiodiscussions.com/forums/introduce-yourself.1088/

    Thanks in advance and have fun!
    RadioDiscussions Administrators

Talking House transmitters

G

Grrrradio

Hey all... I realize this makes me UNSPEAKABLY nerdy, but over the last few months here in St. Paul, I've found and signal-tested a number of those "talking house" AM micro-transmitters, which broadcast looped real-estate messages on frequencies in the X-band.

So far, the best result I've had in my car was with a unit on 1680 kHz, located (if any locals happen to be reading) at the corner of Arlington and Mackubin. With the engine shut off, the signal was weak-but-listenable (probably around 20% effective modulation) at 1/3 mile, and barely perceptible (probably around 3-5%) at 1/2 mile. (With the car on, the engine noise overtook the signal completely at just over 1/10 of a mile away.)

Has anyone else on the board DXed these sorts of signals? What kind of results have you seen? It would certainly be interesting to see how much factors like ground conductivity and atmospheric conditions affect the performance of signals which are so low-powered to begin with. (Also, anyone happen to know approximately how much RF power the Talking House units produce?)
 
100 Milliwatts under part 15 rules which allows unlicensed broadcasting
 
Grrrradio said:
Hey all... I realize this makes me UNSPEAKABLY nerdy, but over the last few months here in St. Paul, I've found and signal-tested a number of those "talking house" AM micro-transmitters, which broadcast looped real-estate messages on frequencies in the X-band.

So far, the best result I've had in my car was with a unit on 1680 kHz, located (if any locals happen to be reading) at the corner of Arlington and Mackubin. With the engine shut off, the signal was weak-but-listenable (probably around 20% effective modulation) at 1/3 mile, and barely perceptible (probably around 3-5%) at 1/2 mile. (With the car on, the engine noise overtook the signal completely at just over 1/10 of a mile away.)

Has anyone else on the board DXed these sorts of signals? What kind of results have you seen? It would certainly be interesting to see how much factors like ground conductivity and atmospheric conditions affect the performance of signals which are so low-powered to begin with. (Also, anyone happen to know approximately how much RF power the Talking House units produce?)
Click to expand...

The Talking House ( www.talkinghouse.com , www.actradio.com , and www.theradiosource.com/products-infomax.htm ) can cover 520 kHz - 1700 kHz, and the TalkingSign ( www.talkingsign.com ) can cover 1400 kHz - 1690 kHz. Both transmitters can use either the supplied 3 meter flexible wire indoor antenna or a special outdoor antenna tuning unit (ATU) with a stock 8.5' (2.59 m) fiberglass CB whip antenna. The outdoor ATU/whip (available from both transmitters' manufacturers) can achieve ranges of 1/4 mile - 3 miles, depending on the local soil conductivity, mounting height, and frequency (greater height and using higher frequencies helps with the electrically-short flexible wire and whip antennas).

-- Jason
 
Comparative test...

Earlier this evening, I had an opportunity to signal-test the unit after dark... In the same direction as the daytime measurements were made, the signal was able to defeat my engine noise for THREE-tenths of a mile. Now I'm curious -- do nighttime conditions somehow enhance the groundwave of an AM signal, or is it possible that even this little peashooter unit was sending out the skywaves that account for most nighttime AM DX?
 
Re: Comparative test...

Grrrradio said:
Earlier this evening, I had an opportunity to signal-test the unit after dark... In the same direction as the daytime measurements were made, the signal was able to defeat my engine noise for THREE-tenths of a mile. Now I'm curious -- do nighttime conditions somehow enhance the groundwave of an AM signal, or is it possible that even this little peashooter unit was sending out the skywaves that account for most nighttime AM DX?
Click to expand...

1680 kHz doesn't have much ground wave propagation. 0.3 miles is awfully close to the transmitter to be getting skywave.

It would have to be NVIS (Near-Vertical Incidence Skywave), but it is possible. The electrically-short 3 meter antenna does have a quite high angle of radiation, and I once read an account of a private pilot who could easily hear Talking House AM transmitters on his plane's Automatic Direction Finder (ADF).

-- Jason
 
Also, the power cords on the Talking House and TalkingSign transmitters radiate some signal (I checked them with a Field Strength Meter). If you set up your transmitters so that their antennas *and* power cords are both vertical, it should increase your range.

The power cord is 2 m (or 6') long and the wire antenna is 3 m long, so setting up a transmitter with the power cord and antenna vertical in a straight line would be rather difficult.

*But*, if you have a room with an electrical outlet high on a wall, the power cord and antenna could be placed vertically and parallel to each other about 18" apart (like a two-tower AM array), which might give you stronger signal lobes in some directions.

-- Jason
 
Status
This thread has been closed due to inactivity. You can create a new thread to discuss this topic.


Back
Top Bottom