I've been using the Talking Sign (pre Procaster ChezRadio) for the past few weeks and it's been working well. However, it has a hum that I've been unable to get rid of - it's difficult to replace the wall wart power supply, as they attach -ve to neutral to get an RF ground, and I'm using the supplied wire antenna run up a piece of PVC pipe.
I managed to get my Procaster working, and then it died again. I guess I'm going to have to bite the bullet and send it into ChezRadio for repair. The Procaster was marginally better than the Talking Sign in terms of audio quality and range, but then, it obviously needs work. I'll have to see how it does when I get it back.
Then I ran across a Talking House transmitter and ATU that I had in storage. So I fired them up - I attached a 99 inch fiberglass whip to the ATU, and have a 19 inch wire running to ground (totals 3 meters exactly).
I was pleasantly surprised with the results. Other than a horrible hum, I was getting far more range than with either the Talking Sign or Procaster and it sounds GOOD!
I first attacked the hum by replacing the cheapo audio cable with a better shielded one - it helped a bit. If you're using the wire antenna for a Talking House, you need to use the supplied wall wart, as, like the Talking Sign, it uses the power cable to attach to an RF ground. But if you're using an external antenna (with an external ground), then you can replace it with a regulated one, which I did (I used an older regulated wall wart from Radio Shack, yes, they used to sell things other than junky consumer electronics). 13.8 volts works fine (center tip +ve). The hum almost completely disappeared! I found and ordered an audio isolation transformer on e-bay and hopefully it will get rid of what little hum remains.
I'm now going to make a very unscientific comment, so please forgive me. Without any specifically measured data to back me up, I would have to say that the Talking House with the ATU in its current installation is working just as well, if not better, than the Rangemaster I had set up last year. And I could never get rid of the hum with that Rangemaster. The Talking House, even with the ATU, is a lot cheaper, too! Plus, it's pretty much plug and play.
that is great news Sir.
I am going with the talking house and it's ATU for my station.
After lots of research I felt it was the best over all transmitter package for both range and ease of setting up.
Thanks for the post.
I have been running a T.H. v5 with the external ATU for over a year now. It has been operating flawlessly 24/7.
Initially I had the hum issues which was solved by using a regulated and well filtered power supply, ground loop isolator in the audio line, shielded audio cable, grounding the T.H. case. A ground to the ATU unit bumped the output meter reading from a 6 to a 9 on the ATU meter. Considering the reasonable cost and "plug and play" installation this is a neat unit.
The next step is deciding what I should use for audio processing. Suggestions are welcome.
When you have finished the installation, I think you will be very happy with the T.H.
A couple of comments and maybe a question.
Question first: Shouldn't the power supply be 18 volts DC? Not 12? This is based on the markings on the rear. Because if it's 12 volts, the unit will not develop full power?
Also, using Palstar zm30 analyzer I was able to find a match using a tuner capable of operating down to 160 meters into 135 dipole fed with ladder line. Not legal in the US, but a match never-the-less. The match used a large amount of inductance and the tuning was very narrow on the capacitor. The antenna cap was fully meshed.
I will let you know about the range.
There was a thread a while back that stated that although the Talking House is rated for 18 volts, it runs fine on 13.8. And it uses the same current at that voltage as well as 18 volts. So there is voltage regulation going on internally. But it sometimes didn't work at 12 volts. My guess is that a lot of cheapo wall warts rated at 12 volts only develop that or less, so they went with a higher voltage. My regulated Radio Shack wall wart develops a solid 13.8 volts at 1.5 amps.
As for audio processing, I use software. VST actually, with plug-ins for compression and to convert to mono (a smart mixer that reduces phase issues). I plan to add an equalizer at some point).
I used to use external compression (a Symetrix 421), as well as an Inovonics 222 (with my Hamilton Rangemaster, which accepts asymetric modulation) but it was a pain with 2 extra boxes and all the extra wires and things. As you can tell, I do a lot of experimentation and switch transmitters regularly.
The TH will run ok with 12vdc but at a higher current rate that if ran at 18vdc. Spot on on the cheapo wall warts with inadequate current capacity as well as filtering and rectification.
The barely readable schematic on the patent information shows the two finals work with an 18vdc source through the modulator/current amplifier circuit. The 18vdc is delivered from a voltage/current regulator circuit in the power regulator section of the unit.
Since the logic and control and ATU motor functions off the 12vdc and 5vdc rails, which all get their source from the 18vdc, those lower voltage circuits will run fine, as does the final at 12vdc instead of 18. But yes the drawback is that the finals will not produce the actual output capability at 12vdc as they would with 18vdc supplying them.
The drop is not significant enough however.
RFB
How is the range on your TH ?
I am shooting for 1/2 to 1 mile with mine .
I will post reports as soon as I get it up and running.
I'm also following your experiment(s) with interest, as I've been considering the TH iAM transmitter and ATU.
Because I'm located on the back of a farm, and not your normal neighborhood, it's a good 1/4 mile to the closet house. There are fields to the east and south of the transmitter site, and a small pasture to the north in front of the site.
The closest neighborhood is to the west, toward town. The Cunningham TX covered it solidly on 1160 AM. The Rangemaster did okay, with the biggest hurdle being a licensed station on 1620 in Pensacola, Fla. that sometimes booms in during the late afternoon and nights. Even at 1610, the signal was pretty much wiped out.
I like the frequency agility that appears to be available with the TH/iAM.
With a good ground connection, I think you will be happy with the range. My TH with ATU does quite well. I have noted that the higher the frequency, the better the range. After a lot of experimentation I found 1580 and 1610 to be the least interference prone in my location.
For your situation, with a station on 1620 that pretty much rules out 1610. Just remember to tune the ATU with each frequency change. Simply done by turning the tuning knob for max reading on the meter.
Good luck.
Mr. radioboy could install a transmitter and antenna at the edge of his property closest to the "nearest house" and run long audio & power cables back to the farm house.
Therefore that "closest house" would be served with a solid signal, and you might be able to hear your station on a good radio back at the farm.
Depends on how you define range. With my ears, the station is perfectly listenable, with some noise, out over a mile and a half in some directions (mostly open fields) using a sensitive car radio. In built-up areas, the noise increases and you get drop-outs, but again, depending on the obstructions and their type, I get up to a mile range of listenable signal, again with a car radio.
Your mileage may vary. I've always found that noise creeps into AM signals after about 1/4 mile, no matter if there are obstructions or not - just the penalty for doing Part 15.
Thanks for the info, RFB. When I get my audio isolation transformer, I'm going to try going back to the original power supply with the transformer (and various other combinations) to see if there's a compromise between minimal hum and the best range.
I won't make the irritating (to you) mistake of jumping right in and asking a bunch of questions, but I thought I might get a few helpful nibbles by just stating my interest in low power broadcasting.
I've been working living history events for a few years now and most recently participated in a WWII reenactment. Leading up to the event, I gathered recordings of wartime radio programs to play through a reproduction 1938 Zenith table-top radio in the barracks, but onsite technical difficulties overcame my efforts.
After the event, I started wondering about the possibility of actually broadcasting these programs within the confines of the camp. I recalled there was some government provision for license-free broadcasting; a few internet searches turned up Part 15 and Talking House.
Having "cornered the ebay market" for a few days, I now own several TH units including a TH 5.0, several TH II (which I've offered to a historic site for a possible automobile-tour use), and a TH 4.x that thus far cannot complete its autotuning process without displaying 'err').
Neither of the two newer units came with the factory-provided indoor wire antenna, so I improvised with an about-10-foot-long piece of insulated 14-16 gauge stranded wire. So far the outdoor reception has been less than ideal, so for the near term I'll be searching the message archives for antenna placement and orientation tips.
Frankly, I feel that this is an ideal use for the Talking House setup; given the relatively low-fi quality of 1940s radio programs, I don't need a hi-fi system like most of you 'serious' low power broadcasters.
Hello blbachman, this indeed is the part 15 website where "the buck stops."
An AM indoor antenna will work well indoors, but unfortunately by the time the signal travels through the walls and construction materials, quite a bit of "punch" is lost.
I have breached the divide by what I call the "Wintenna" I place the transmitter at the baseboard below a window, run the antenna wire vertically up the wall to the window sill, underneath the closed window, and attach the wire to the metal outer storm window (or screen). Then on the outdoor side I attach more wire using self tapping screw, to the top of the window frame and travel upward until the sum total of the entire string of metal amounts to 10-feet.
For RF ground signal you run equal lengths of wire, each about 30 to 50 feet long, along the baseboard, both pieces of wire joined at the center and attached to transmitter ground. This is a dipole being used for a ground plane.
This Wintenna covers the Entire indoors and does very well outdoors.
The Talking House sounds good enough to me for most broadcasts, including music.
And for vintage radio programs where the sound quality isn't up to modern standards, it's as good as anything else.
If you don't want to invest in an outdoor ATU, why don't you do what I did for a similar transmitter (the Talking Sign). Run your wire inside a piece of PVC pipe, leaving enough for a short feedline to your Talking House. Mount the TH inside on the wall up near the ceiling, and run the feedline through the wall to your PVC pipe, mounted as high as you can get it outside. You'd be amazed at how well this works (I was able to get well over a mile range in some directions over an area which had relatively few obstructions - mostly open field).