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Originally posted by Skippy
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take TM800 schematic of Discovery. it's due correct. -
Yes TM800 is exactly the same as TF-900.
Designators on components... well, that's probably my guilt!
When I draw schematics and later pcbs; I don't follow nor respect what's written on original pcb, but I am putitng designators as I draw part by part... which is WRONG, I admit.
Old and very wrong practice. I have to change that bad habit.
Even I later have problems to follow and compare the works like that.
My mistake!
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Test results; 11V/60ma, U@50cm = 0.7 V, 10 kHz. For comparison 20cm my regular coil gives 1.2V
8.6 kHz, U@50cm = 0.55 V
20 cm
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Possibly so, but I am always guided by the schematic not by the pcb, I use this if I have any doubts, for example. with the resistance of 6k8Comment
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COILS :
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I don't know how valid such tests are.
It is a thin wire threaded through the toroid, and the inductances are not accurate.
And on the device there is an aluminum rod that passes through the toroid exactly and at a right angle.
It is an old truth that without mechanical stability there is no electronic stability either.
I didn't go into that much detail, I just copied the original. And it works correctly.
I didn't measure anything with an oscilloscope because there was no need.
The less I know - the better!
The quality of the coil is certainly influenced by the regularity of the winding, the right diameter of the wire
and the right choice of toroid material, because toroids differ drastically in permeability.
In addition, the way of coupling the coil on the toroid with the antenna is such that in such a cramped workshop the antenna will pick up all possible interference.
The most difficult part in the production is definitely the antennas as well as the coupling itself. That's where I paid the most attention. Not by measuring,
but by precisely copying the original, as well as paying special attention to mechanical stability.
In one part, the antenna is connected directly to the boom, which is certainly not the same as copper wire threaded through the toroid.
That is a "feed point" and the opposite side that is in direct contact with the boom is the lowest potential,the ground.
I don't know what to say... improvisations will not produce results.
While on the opposite side it is completely isolated at the point of passing through the boom.Comment
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What you see on this sketch is complete "antenna" along with boom. Not just bar and the toroid. In next post I will post the sketch of coupling point and ground point on boom.
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And the boom is in direct contact with enclosure and with GND on PCB.
In radio jargon, what you see in the sketch is actually a "closed (folded) dipole", with center ground.
Which further means that it is a "symmetrical" antenna.
Quite different than plain wire "ring" passing through toroid, without ground point.Comment
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no good contact there. just a paint cover. no need electric in Nature contact, possible some ELECTROSTATIC conductivity the paint does.Comment
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Not surprised, similar to yagi TV antennaOriginally posted by ivconic View Post
And the boom is in direct contact with enclosure and with GND on PCB.
In radio jargon, what you see in the sketch is actually a "closed (folded) dipole", with center ground.
Which further means that it is a "symmetrical" antenna.
Quite different than plain wire "ring" passing through toroid, without ground point.
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The original was created thanks to measurement, haw you know that your Tx copy has the same preferences as original?Originally posted by ivconic View Post
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A clumsy choice of terms by me. Of course I measured all kinds of things. But I didn't measure anything with the oscilloscope.Originally posted by pito View Post
I didn't even measure the frequency.Comment
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You're probably right. I deliberately made a very good contact on my "antennas". Because that makes more sense to me.Originally posted by kt315 View PostComment
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