T Attenuator Termination Kluge
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Re: T Attenuator Termination Kluge
-56 dB at cutoff seems high to me.
https://ka-electronics.com
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“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50
Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://waynekirkwood.com/content/Plandemic.mp4
Re: T Attenuator Termination Kluge
You would expect more attenuation at the fully CCW position right?
Re: T Attenuator Termination Kluge
It could be your board, and the fact you are going balanced to unbalanced and back. But I would have thought the last position of the attenuator would be an off position, with very high attenuation.
Re: T Attenuator Termination Kluge
I figured it out. The 10K TKD didn't like the 5K termination resistor for the T attenuators. When I bypassed the termination resistor I got over 80dB cutoff. I'll have to think about the wiring now. If I put the TKD before the 5K Bridged T switches they will still see a 5K load, so that probably won't work. I guess I could terminate the 5K Bridged T at the attenuator. Feed the TKD pot after the termination and use a higher value termination resistor on the PCB's.
Re: T Attenuator Termination Kluge
It turns out it had nothing to do with the termination resistor. There were a few things that needed sorting out. The major thing was a different grounding scheme. Now I get cutoff better than the Portable One can measure.
I had to put the TKD pots before the Bridged T attenuators. The 12Ω-14Ω series resistance was enough to throw the gain steps off by too much. Now with the pot before the attenuators I'm getting gain steps that are within a few hundredths of a dB accurate. Channel matching when using the pot looks like it's within about 0.2dB over the whole throw.
I had to put the TKD pots before the Bridged T attenuators. The 12Ω-14Ω series resistance was enough to throw the gain steps off by too much. Now with the pot before the attenuators I'm getting gain steps that are within a few hundredths of a dB accurate. Channel matching when using the pot looks like it's within about 0.2dB over the whole throw.
Re: T Attenuator Termination Kluge
If at first you dont succeed, keep at it! Well done!
Re: T Attenuator Termination Kluge
Thanks. I’m happy with it. Crosstalk -90dBu at 20K. The input is AC coupled. After that everything is DC coupled. Now I have to put the new pot in the other Output Amp.
Re: T Attenuator Termination Kluge
Good news. T attenuators get screwy so easily if the surroundings are funky. I have measured so many odd things.
Best,
Doug Williams
Electromagnetic Radiation Recorders
Doug Williams
Electromagnetic Radiation Recorders
Re: T Attenuator Termination Kluge
I'm seeing something I don't understand. When feeding a 1K 0dBu tone in, with 11db of gain (zero attenuation with the attenuators) and the fader fully CCW I get a kill below the measurement range of the Portable One. With the fader still all the way down I get a kill of -86dBu with the attenuators at -3dB (8dB of gain). When the attenuators are at 0dB on the dial (-11db gain) I get a kill of -79dBu. It stays at that value for the rest of the switch positions. I get more kill with 11dB gain than I do with -11dB. -79dBu isn't a deal killer but if I can improve it I'd like to.
Re: T Attenuator Termination Kluge
I spent some time trying to improve this. I noticed there was 20KΩ to ground at the Unbalanced Output feeding the Fader-Attenuator. I sub'ed in a couple of values and saw a pattern. Then I put a rheostat in place of the resistor and adjusted for the deepest cut. Curiously the value was 2k5Ω. Half the termination resistance. Then I tried changing the 5KΩ termination resistor to 2k5Ω. Bingo. I have a 6dB improvement now with a cut of -85dBu at the "0" position (11dB of attenuation). Close enough for government work.