But I'm the HEAD of the cabal!
I'm not just a member or friend of the cabal, but its leader!
To me that sounds like praise.
It also speaks highly of PhilB, a man so connected that he has his own cabal.
I will be happy to attack you Carl if that will make you feel better.
I don't want to be left out of any verbal attacks against the intellectual part 15ers here on this site, but if I'm the sole target of a verbal attack I'll want an explanation why the others aren't also included.
Don't worry, Carl, they've been pretty inclusive 'over there', attacking and belittling everyone who is here on this Forum.
The latest laugh I had was that the originator of the Challenge went out and bought a new style case for his ProCaster. Some had questioned whether or not the ProCaster used in the Challenge was the latest model because it had the old-style case. He explained that it was the latest, obtained directly from ChezRadio. Fine enough - a reasonable question and and a good answer. Done.
But now he's gone out and purchased that case so that the 'less knowledgeable' can't attack any future testing results. Really? I guess if it makes you feel good, go for it, but I don't see any value in swapping the case. There are plenty of other bigger things to worry about in future testing than that.
Those with 10 minutes or so to spare might be interested in a read of the thread on this topic appearing on another site, starting at the link below:
http://radioinsight.com/community/topic/transmitter-challenge-of-part-15-transmitters/page/2/
My ID there is RF Systems Engr (retired), because for some reason when I signed up there as Rich, an RF Systems Engr (retired), those fields are reversed in my posts.
Very good read over at Radio Insight, thank you Rich for the link.
Just before the challenge fellow lost his cool and began throwing old laundry, he made what might pass as an authoratative remark, but which actual meaning eludes me and I can't get my brain around it:
He said: "Judging strictly by the build quality of many of the kits I would expect their field strength to be less than the higher end more sophistcated transmitter offerings."
What this seems to say is that 100 milli-Watts works best if it's expensive and well built. That would mean that a hundred milli-Watts badly built just won't be the same.
You are to be commended, Rich, for "standing your ground" (pardon the expression) on the matter of long-ground leads and lightning protection which seemed to un-hinge the poor fellow causing a grammar avalanche that actually got worse the more enraged he became.
Perhaps the ALPB will provide sensitivity training as to handling those delicate easily bruised hobbyists.
What was also hilarious about that thread (other than the same old same old by good ol' Bill) was the post about this Forum, and the out of context (and incorrect) paraphrasing of criticisms regarding the Challenge made by moi. Probably made by a friend of his - perhaps I'm hitting a nerve. Particularly since it has been admitted that the Challenge testers did not fully understand how to tune the AMT5000.
I think it all boils down to too many variables in the testing. If you're going to do a comparison, you'd better keep as many things constant as possible (i.e. ground, antenna, source of transmitters, etc.), and have the requisite knowledge to do it correctly.
I too applaud you, Rich, for keeping the pressure on. I don't think I have the interest to continue much longer, at least with words. I'm just going to do some more of my own testing (without a FIM) and report the results here.
Never jump onna trampoline after ingestin' a fizzic..
Avoid coughin' and sneezin' at all cost!
And most of all, don't mess with 'ol Sparky, 'cause he'll eatcha up!
Kudos, Rich... 😉
🙂
The dubious testing in the Challenge has been justified by the 'rule' that transmitters would be used as they were delivered from the manufacturer. And that includes documentation - the intent was that a newbie could use the results to properly choose a transmitter.
I was just doing a bit of research, and went to the web sites of SSTran and the Rangemaster. Apparently, the Rangemaster DOES NOT get delivered (from Hamilton) with any antenna at all. So, to be consistent...
On their web site, SSTran states very clearly that the wire antenna delivered with the AMT5000 is intended to be used indoors - they recommend using a whip or pipe antenna outdoors (which is where the testing was conducted) and they even have references to the building of a base loaded antenna (the internal tuning circuitry can be bypassed to use such an antenna). You can't order their transmitter without going to that website, where even a newbie would see the information.
On his own private web Forum, the originator of the Challenge has just stated that no manufacturer has contacted him regarding the results of the tests. Given the warm welcome given to anyone and everyone who has even attempted to question anything at all about the Challenge, what would be the point? I'm sure the manufacturers see what's going on, just like everyone else.
And finally, with regard to the tuning of the AMT5000, it's been admited that the testers did not know how to correctly set the values of several jumpers. It was freely admitted that the SSTran would likely have performed better if they had. And yet they made to effort to get that information, even though they knew that the results for the transmitter would be wrong. Much has been made about the depth of broadcast engineering experience the testers had, and yet here they acted in a fashion that even a newbie wouldn't - a newbie with any common sense at all would have found out the answers to his/her questions before forging ahead and getting erroneous results.
On their web site, SSTran states very clearly that the wire antenna delivered with the AMT5000 is intended to be used indoors - they recommend using a whip or pipe antenna outdoors (which is where the testing was conducted) and they even have references to the building of a base loaded antenna (the internal tuning circuitry can be bypassed to use such an antenna).
A base-loaded, constant-OD, linear conductor with a physical length of 3 meters needs the following inductance to resonate on 1640 kHz, the test frequency used in the Challenge:
OD, inches.........AWG......Inductance, µH (approx)
0.0641, wire...........14...................406
0.1285. wire............8....................367
0.2576, whip...........2....................328
Note that that radiation resistance for a given conductor length and frequency is independent of the OD of the conductor.
As no mention was made in the text of the Challenge report that the AMT5000 antenna system was not tuned to resonance when tested, we'll have to conclude that it was tuned to resonance, regardless of the OD of the antenna wire that was supplied with the AMT5000.
LESS inductance is needed to resonate conductors having large(er) OD, so it is likely that the internal loading coil in AMT5000 would be able to resonate an external whip antenna, given enough taps on that coil.
Probably the fact that the AMT5000 internal coil can be bypassed for antenna systems using an external loading coil accomodates those who might use a loading coil having less r-f loss than the one in the AMT5000. Maybe PhilB could comment on that...?
For other conditions the same (physical geometry, resonance, power at the coil output, ground connection loss, etc), it would not affect the results of the Challenge whether the AMT5000 used a wire conductor of 14 AWG or even smaller or a 3-m whip as its antenna, as long as the wire was stretched out to be linear and in the vertical plane, and was not affected by nearby conductors.
Conclusions:
1. The internal loading coil in the AMT5000 can be used to resonate an external 3-m whip, assuming tap resolution permits setting it to the needed inductance, and
2. The performance of the AMT5000 in the Challenge cannot necessarily be attributed to its use of a wire antenna rather than a whip.
God Bless you Mr. Fry for bringing sanity to this discussion. No B.S.!
As yet undiscussed is how close to the transmitting antenna the test crew were standing. Being near or far from the antenna can affect performance.
This is another detail missing from the Challenge, and it matters.
I don't disagree with the antenna theory, Rich (and wdcx). But there's theory and then there's practice. I've learned from over 8 years of actually doing Part 15 broadcasting that what works in theory doesn't always hold in the real world. Not saying that it wouldn't - just that we don't know from the Challenge because they didn't use a whip on the AMT5000. You can talk all you want about what might have happened - but the entire point of the exercise was to do it. They just did it poorly.
My comments on the use of antennas for the AMT5000 actually stem from the strict adherence to the rules that were set up for the Challenge from the start. That they would only use the antenna that was delivered with the transmitter (then the Rangemaster would have had no antenna, as it doesn't come with one from the factory - they obviously decided to overlook that particular fact). And that they would use the documentation as delivered with the antenna. The reasons - they wanted a newbie to be able to use the results to choose the appropriate transmitter.
Bill D. has stated that nowhere in the documentation does SSTran recommend using antennas other than the wire that is delivered with it - I wanted to point out that that statement is effectively false, as their website does talk about that, and even a newbie has to go to their website to buy the product.
I've come to the conclusion, however, that the main reason the AMT5000 did so poorly in the Challenge is that they didn't tune it properly. Bill D. wrote over at Radio Discussions what I posted previously - he admitted that it would have performed better if they basically knew what they were doing. The documentation was blamed, but I blame the testers for not doing what anybody else would have done, including newbies - finding out the correct information before proceeding.
The only BS I see is that coming from the Challenge people.
And it could all have been avoided if they hadn't taken the comments and criticisms so personally. You're supposed to leave your ego at the door when you do experiments of this sort.
Another detail that was sketched over was the length of the copper ground rod used in the test.
8 or 10-foot length would perform dramatically better than a 3-footer.
Not too late to add some of these details, to the degree they are known by the engineers.
One more compalint about snideness: the remark "Kit transmitters are currently exempt from certification requirements."
No! That's political baiting, and the correct statement would be: "Kit transmitters are exempt from certification requirements."