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Help with my SSTran AMT3000

Deano

Deano

I bought an AMT3000 almost a year ago but just got around to really playing with it tonight. Wouldn't you know...I have misplaced the manual. Could someone with a schematic tell me which jumpers to adjust (and in what positions to put them) to configure the on-board RF filter inductors to isolate the transmitter ground from the power lines, and from paths to ground through the audio inputs. I have a very mild hum when the radio is running on batteries. Plug the radio into the wall (anywhere in the house) and the hum becomes VERY loud!

Question two, should I install a special ground rod outside for the transmitter or hook up the ground to something else? If my hunch is correct about the hum, the ground side of the house wiring seems to be a bad idea. Coverage is minimal with the wire antenna and ground side unhooked. It barely gets across the house. I'm not looking for blocks of coverage but it would be nice to get a usable signal into the front and back yard. My TH II has 10x the coverage but sounds horrible. Looking for any ideas that might help.
 
I can't help with your AMT3000, but as for your Talking House TH II, have you ever tried feeding the audio to it through a compressor/limiter such as a Behringer unit?

All of my TH II's have decent sound by themselves, but the Behringer gives them extra "oomph." -- Jason
 
What kinda coverage do yt'all get with the Talking Houses? As I understanbd, you can use em as is or add an antenna...
 
PaulBWalkerJr said:
What kinda coverage do yt'all get with the Talking Houses? As I understanbd, you can use em as is or add an antenna...
Click to expand...

With the outdoor ATU/8.5' whip antenna (available from Talking House and Information Station Specialists), the range is anywhere from ~300' to a mile or more.

If you set one up on the second or third floor of a wooden house using the supplied 3 meter flexible wire antenna with the unit on the floor in the middle of an empty room and the antenna hung from the ceiling, you might get out 1/4 mile - 1/2 mile. Adding a copper foil or aluminum foil ground plane under the transmitter would improve the range somewhat.

A lot depends on the local soil conductivity, how well the outdoor ATU is grounded (RF ground, not DC ground), how high it is mounted, and what frequency is used (higher is better with the electrically-short whip antenna). Talking House/ATU/8.5' whip installations at marinas often achieve ranges of up to 3 miles due to the excellent conductivity of salt water. -- Jason
 
Even with Florida's bad ground conductivity the 3 meter wire antenna inserted into a 3 meter piece of copper tubing covers about a block with my TH II. Decent coverage but even processed with a good compressor/limiter it sounds horrible.

The AMT3000 using the included 3 meter wire antenna gets me about 50 feet but sounds like a million bucks! If I can just lick the hum issue and cover my whole yard. :)
 
Deano said:
Even with Florida's bad ground conductivity the 3 meter wire antenna inserted into a 3 meter piece of copper tubing covers about a block with my TH II. Decent coverage but even processed with a good compressor/limiter it sounds horrible.

The AMT3000 using the included 3 meter wire antenna gets me about 50 feet but sounds like a million bucks! If I can just lick the hum issue and cover my whole yard. :)
Click to expand...

How old is your TH II? The newer ones with the two-part message option (they have an extra two-position slide switch on the back) do sound better than the older units, even without any audio processing. -- Jason
 
There is no two-message switch on my TH II. If you push the modulation level at all you get a ball of distortion. With a good compressor/limiter you can get the modulation up to about 1/2 that of the other stations on the dial. The frequency response deplorable. It sounds only slightly better than a phone line.

My AMT3000 almost sounds like FM on a wideband AM receiver like my GE Superradio. If I can overcome my housewiring/hum issue and get a little more RF into the front yard (so I can listen while I mow) I will be a happy camper.
 
Deano said:
There is no two-message switch on my TH II. If you push the modulation level at all you get a ball of distortion. With a good compressor/limiter you can get the modulation up to about 1/2 that of the other stations on the dial. The frequency response deplorable. It sounds only slightly better than a phone line.

My AMT3000 almost sounds like FM on a wideband AM receiver like my GE Superradio. If I can overcome my housewiring/hum issue and get a little more RF into the front yard (so I can listen while I mow) I will be a happy camper.
Click to expand...

I've had the 60 Hz AC hum on my Part 15 AM transmitters (Talking House, TalkingSign, and Gizmo) when using my computer as the audio source. I cured it by using a Radio Shack car stereo ground loop isolator (the one with the cylindrical case) in the audio line. I don't know if that would help with your particular installation, but it might.

I know what you mean about the older TH IIs. They have a "talking into a coffee cup sound" that is fine for advertising houses, but lousy for listening to music. -- Jason
 
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