AT1 question
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I received an off list responce that said my thinking was ok....
OK..... Then why am I getting 0.2 volts out? And with 1dB selected, I should be getting 0.8928.....but I get 0.9936 with either 1dB switch selected..... YET, all of the resistors are installed correctly and the suggested resistance checks are all but dead on. When viewing the schematic, for a 1dB factor, there is a 5.6 ohm in series with a 910 ohm and the output is across the 910. Using ohm's law.... It looks like I should be getting out what I AM getting out. Confusion has set in... I may need a Corona or two to figure this out Harlan NC3C ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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dB = 20 * Log (Vout / Vin)
73, David W4DES On Jun 6, 2014, at 4:21 PM, [hidden email] wrote: > I received an off list responce that said my thinking was ok.... > > OK..... Then why am I getting 0.2 volts out? > And with 1dB selected, I should be getting 0.8928.....but I get 0.9936 with either 1dB switch selected..... YET, all of the resistors are installed correctly and the suggested resistance checks are all but dead on. > > When viewing the schematic, for a 1dB factor, there is a 5.6 ohm in series with a 910 ohm and the output is across the 910. Using ohm's law.... It looks like I should be getting out what I AM getting out. > > Confusion has set in... I may need a Corona or two to figure this out > > Harlan > NC3C > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Harlan Sherriff
that is the equation I'm using to figure what I "should" be getting out... But that's NOT what I'm getting. And, the reading im getting agree with the value of the resistors used in the voltage divider.
Sent from my Verizon Wireless 4G LTE DROID David Sanders W4DES <[hidden email]> wrote: >dB = 20 * Log (Vout / Vin) > >73, David W4DES > > > >On Jun 6, 2014, at 4:21 PM, [hidden email] wrote: > >> I received an off list responce that said my thinking was ok.... >> >> OK..... Then why am I getting 0.2 volts out? >> And with 1dB selected, I should be getting 0.8928.....but I get 0.9936 with either 1dB switch selected..... YET, all of the resistors are installed correctly and the suggested resistance checks are all but dead on. >> >> When viewing the schematic, for a 1dB factor, there is a 5.6 ohm in series with a 910 ohm and the output is across the 910. Using ohm's law.... It looks like I should be getting out what I AM getting out. >> >> Confusion has set in... I may need a Corona or two to figure this out >> >> Harlan >> NC3C >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[hidden email] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Harlan,
You should get 0.1 volts when you terminate your attentuator with 50 Ohms - are you probably using a high z voltmeter? The output of the attentuator can be seen as a 0.2 V voltage source with 50 ohms internal resistance - if you terminate it with a 50 ohms load, the 0.2 volts are divided between the internal resistance and the load, but if you use a high z termination instead, the voltage drop on across the high z is 0.2 volts... Greetings Ralf, DL6OAP ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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