The day started with Screw Terminal Blocks, continued into Power and Audio Jacks, and completed Small Inductors when break time arrived and time for a banana.
That's happy news about the guy who is already testing his AMT5000.
The board layout is a grand work of art. Nobel Prize!
"break time arrived and time for a banana"
Save them peels as those are useful in removing light scratches off CD's and DVD's.
RFB
The banana treatment for compact disks is useful information, RFB. I check out a lot of movies from the library, and the librarians will enjoy hearing that cure. I think the public plays pizza fingered frizbee with the DVDs.
Where are we in building the AMT5000? Just did Electrolytics, which sounds like a field of study from theology school, Quartz Crystal, Toroid Inductor, Variable Resistors, and stand poised to do LED Power Lamp and Insert ICs into DIP Sockets. Now only a page away from being fully done.
Had a tomato sandwich on sour dough bread with mayo. Does that make you hungry? That's an example of "the power of suggestion." We should be able to use that power to promote Part 15 broadcasting.
In went the LED Power Light, ICs into their sockets, and all preliminary jumper switches.
Plan to test on 1640kHz, a blank daytime spot not normally in use.
Set the frequency synthesizer for 1640 and the toroid inductor for that range.
Everything is probably ready to apply power, but another inspection of the circuit board and further manual study comes first.
Wait here, I'll be back in a few minutes.
Later that same day, after reviewing the manual and gathering an understanding of what each jumper switch does, I powered up into a CB whip which is attached to the antenna terminal on the AMT5000 by a 1-foot clip lead. It's less than 3-meters, more like 1.5-meters, but I reason that seeing it operate at less than optimum I will be able to more easily spot changes when output tuning is varied.
My first test frequency, 1640, was a bad idea because the AMT3000 operating at 1680kHz with cage monopole is ultra-strong, even 20-feet from its antenna. For one thing, my C.Crane Radio Plus hears traces of 1680 audio when tuned to 1640. When the AMT5000 was turned on at 1640 it caused a very loud image of 1680 to appear, albeit distorted.
Here is my theory about why I was getting so much interference from 1680: I suspect the toroid inductor is so resonant in its operating range it was causing the CB antenna to be very sensitive in the 1640 to 1680 range, so much so, that it was capturing plenty of energy from 1680.
Next I picked a frequency farther away, but still within the above 1350 region, per the manual's instructions for high band operation. I picked 1400kHz, and now I have a clean quiet carrier on that spot.
The S-meter was at about half-mast, so I cranked the radio's volume to hear buzzing behind the carrier, and tuned C1 until the noise decreased, then raised the power to the input of the final until there was no background behind the carrier and the radio's S-meter was peaked.
The AMT5000 is declared ready for service at 2:55 PM this date, local time (CDT).
Party. My place. Bring portable radios.
"The AMT5000 is declared ready for service at 2:55 PM this date, local time (CDT)."
That's great! Have you tried it on the antenna system in place of the 3000?
RFB
My secondary frequency is 1550kHz, from an AMT3000 into three-elements forming a triangular cage monopole, two of those elements consisting of 6-foot high aluminum window frames in the wall.
As you recall, adding each element of a cage monopole lowers the total antenna impedance by 1/2 from that of a single 3-meter antenna.
That lower impedance, now with the new AMT5000 freshly installed at 1550kHz, does of course not match up with the recommended settings for top resonance, therefore some work lays ahead fiddling my way to the proper tuning. However, as it is now, the signal seems equal to what it was with the other transmitter.
Once true resonance is achieved, the big question will be whether a noticeable improvement in range can be detected.
Probably by tomorrow.
I will say this about this antenna installation which makes it interesting. The rear of the house faces into a hill which continues to travel upward for 150-feet and then there's a McMansion up there like some kind of a giant sky bound tool shed. It is not a great spot for a transmitting antenna. But that's exactly why I love it. Back there, if I can discover an improvement, it is definitely noticeable. For example, the signal faded out quickly with only a simple 3-meter antenna. But the cage-monopole filled in with solid signal out to the edges of what formerly was only weak signal. Yet, it didn't extend the range, which is less than 200-feet.
EDITOR'S LATER ADDITION: It is important to mention the long ground wire that runs at ground level up the hill toward the back (south) because it alone has been successful in projecting our AM signal uphill. But the reason for mentioning it now is the added impedance load the ground side also introduces to the AMT5000 setup. The earlier trial test had no antenna ground attached.
I will not get a new version of Windows unless it is at least in the SP1 state. Being an early adapter is not for me. Missing, or even excess, components are troubling to me. It indicates a QC problem. Back when kits were common, problems with component count were rare, although they occasionally happened.
I'll be looking for posts and product reviews from the early adapters. At the asking price, which I think is a little less than a bargain, perfection is not too much to ask.
side by side pictures of rangemaster and sstran. am10000 on right amt5000 on left.
To Carl and others assembling the AMT5000:
I highly recommend that you spend some time familiarizing yourself with the tuning procedure on the bench with the 10 ft whit antenna wire attached before venturing forth with other antennas.
Connect the white antenna wire and stretch it out to full length avoiding proximity to conductive objects within a couple feet. Horizontal or vertical orientation is not important for this familiarization process.
Attach the black ground wire to anything grounded on your bench or connect it to the screw on an AC outlet.
Set your frequency to about 1500 kHz (midpoint of the toroid tuning range of 1350 - 1700 kHz). Carefully follow the instructions in section 8, RF Tuning. Be absolutely sure to use a voltmeter connected to the "RF INPUT CURRENT" or a field strength meter if you have one. Use the recommended tap point for the frequency and carefully watch the meter while rotating capacitor C1 through its range. Try the tap points below and above the suggested one to see the effect on the meter reading as you adjust C1. Make sure you find the PEAK setting. The peak should not be at either extreme of C1's range. If it is, move the toroid tap to the next adjacent tap one way or the other until the peak is not at the extremes of C1. After peaking, ROTATE C1 ONE FULL TURN CLOCKWISE from the peak. This is important for maximizing efficiency Overall efficiency will increase by 10% to 20% above the efficiency at the peak meter reading point, depending on your operating frequency.
Once you are familiar with tuning and the meter readings, then you can venture forth to other antennas. Antenna capacitance is very important. The tap points suggested in the manual for various frequencies assume the antenna capacitance is in the 25 pF to 30 pF region. This will be true for a 102" stainless steel whip, a half inch or three quarters inch copper pipe a few inches less tan 118 inches and the 118 inch white antenna wire. Other shorter, longer or fatter antennas will have lower or higher capacitance respectively, and should not be used until you are thoroughly familiar with the effect of the toroid taps.
Tuning by ear isn't really possible if you want to get peak efficiency and performance.
"ROTATE C1 ONE FULL TURN CLOCKWISE from the peak"
Wouldn't that take it 360* away from the peak with that canister cap?
RFB
C1 is a multi-turn air piston capacitor with range of .6 pf to 6 pf. It covers the range in about 7 and a half full turns. One full turn is only about .7 pf.
The "RF INPUT CURRENT" vs. capacitance graph looks kind of like a horizontal S. As you increase the capacitance, the current will rise to a peak. Then, further C increase will cause the current to ramp down to a low trough and then rises up a little from there. The sweet spot is the midpoint in the downward ramp between the high current peak and the lowest current trough. This sweet spot is very closely approximated by turning C1 one turn clockwise from peak. Finding the peak tuning point is critical to good tuning. Then the efficiency goes up quickly as you advance down the ramp. Being off by plus or minus a quarter turn will only affect the efficiency by <1%, so the "one turn clockwise" step is a fast way to get good efficiency without tedious meter readings or dragging out a scope.
Phil
It was actually yesterday, in my entry titled "On Air," that I proved that my freshly built AMT5000 worked the first time it was turned on, and I matched it to a CB whip that was close to the test setup suggested in the manual, and it tuned right up.
What I am unable to do is report on its range, because I (as yet) do not have a proper grounded yard antenna.
That leaves for another builder to report on range tests. I am not trying for greater range.
RFB asked what kind of results could be observed by substituting the AMT5000 for my AMT3000,s and those tests are invalidated because the "antennas" in both cases violate the cautions given by PhilB in the manual: Page 24, "For best range... the antenna should be positioned away from grounded metal objects..."
As I've previously described, my antennas are, by definition, grounded metal objects, namely aluminum window frames mounted in walls. It works, but must be very lossy, varying as to whether the outside is moist or rainy. These are not by any stretch the type of antennas for which these transmitters are designed. Any report involving such irregular antennas would be unfair and meaningless.
In any case, I have no doubt that the AMT5000 will do exactly what PhilB describes, given the intended antenna.
While slowly planning to build a real antenna, the AMT5000 is attached to the CB whip on the bench, and I ran two experiments:
-Using guesswork I set it up on the test frequency 1400kHz and walked 110-feet away, hearing the weakest of signals by the end of the path.
-Using PhilB's instructions for peaking with a multi-meter I again walked out and the end of the path had a signal as strong as at the start! This only with an indoor whip! Range? Phil gives you range! But follow the steps.
Before shutting down the test I calculated the power input to final which is 286mW. Being indoors and only briefly testing this is no problem, but it is great to know that the AMT5000 permits setting the input to the final to the legal 100mW and I'm studying the method for setting the power.