So the first of two TH transmitters came in today.... (black model with live and chip switch)
Using the crapy "nub" antenna connector with the ATU buit-in I was able to get a range of no more than 250'
It was ground level with its 3 meter wire antenna.. Obviously not the best setup.
But being outdoors I expected better than that for the first try.
My question is, what is the best way to attach a homebrew antenna to this unit? Can the F connector be used if the antenna is tuned? or only usable with the ATU built for it?
Do my results seem normal?
Before I was licensed (ham license) I once tried taking a 10' antenna and soldering it to a cheap part 15 car transmitter on the FM band, it traveled a good block no problem and was quiet clear. (yes I know that was out of spec/illegal, this was before I knew anything about radio regulations)
I'm concerned something might be wrong with this unit as I've always been under the impression that the AM band had much better propegation than the higher frequencies used for FM broadcast.
The ATU is intended to be used with a standard 102 inch whip and you connect it to the F connector.
Similarly, if you use a tuned external antenna, you would connect it to the F connector, bypassing the internal tuner.
There are so many factors contributing to the range of a puny Part 15 AM signal. For example, was your wire antenna perfectly vertical? When I experimented with the TH and other similar transmitters, I ran the wire up inside a small PVC pipe and had the end hang out the top a little bit.
What was the receiving radio? You'll get the best range by far with a car radio/antenna combination - consumer type radios have very poor sensitivity and selectivity or adjacent channel interference rejection (selectivity is often forgotten about, but with poor selectivity nearby strong signals can bleed over into your frequency as noise and greatly diminish perceivable range - you may not even hear the other signal but it can be there).
The Talking House with the wire antenna is grounded by the electrical outlet - is it a newer house up to spec in the wiring, but is it older, where such grounding could be suspect? You could try grounding the chassis of the TH with a short wire to a stake pounded into the earth to see if that improves things.
So the 250 feet could be quite ordinary, or not, depending on these factors and others (Did you try other frequencies? What was the weather like? What time of day was it? Were there obstructions between your radio and the wire antenna? etc.)
Thanks for the information
It was at dusk, the antenna was not "perfectly" vertical, the antenna was outside and I was using a car stereo to rx the signal....
Before I could get down to the end of the driveway it just completely dropped off.
The house is older and someone ripped the ground off of the building, I fixed it a while back but only with a large clamp rather than some type of bonding so its certainly not the best case scenario.
I replied earlier but..... idk where it went...
I just went outside to check, night time prop is killing me, every single tunable frequency on the AM band is live and loud out here, there is not one break for another station.
710khz is dead during the day, I'll have to try again around noon... and I'll put a timer on the transmitter to shutdown at dusk and come on at dawn.. Hopefully that comebo saves me here.
first, build a loading coil similar to this:
I wound about 100 turns of #20 magnet wire on a 3" PVC and put taps on every turn for the first 15 turns (from the top) and a tap every 11 turns from the bottom, that way you can get number of turns between 1 and 100. This is more than sufficient for a T.H. with a 10' antenna.
Then take a short piece of coax with connector, and strip it back. Solder a short piece of thin wire with an alligator clip and attach to a lower tap and hook your antenna wire to the upper tap. Move the alligator clips to maxiize the signal. Somewhere around 55 turns worked the best for my setup.
switch the talking house to External Antenna Mode; then take a sh
As a ham, you shoud know a tuned system is critical with flea power, and, yes, the receiving system makes a big difference.
710 khz will not get very far even with a tuned antenna for a couple reasons. The idea is to load a legal antenna as efficiently as poossible, therefore, with such a short antenna, a loading coil will be more efficient with less wire/turns. The higher the frequency the shorter the wavelength. At 710 khz, the loading coil would have to have so much wire it would lose too much to be efficient.
Also, lower frequencies are more effectient in the near field (one of the reasons for using them with CC installations), but drop off quickly after that, according to the spec frequency. I can't run numbers here at the moment, but loading coils work best above 1500 khz.