Re: [K3] [Elecraft] Questions about ARRL review
disc ceramic capacitors - bad for IMD! If there is a problem with those capacitors at 30dbm, I am wondering about the power amps especially SS where ceramic caps are used extensively. Seems nearly all amp's IMD cam generated in those caps. Am I missing something? Ignacy -- View this message in context: http://n2.nabble.com/Questions-about-ARRL-review-tp1583996p1589721.html Sent from the [K3] mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [K3] [Elecraft] Questions about ARRL review
Not all disk caps are the same - it depends on the dielectric. NP0 types are pretty good but the high K formulations, Z5U and Y5U are not so good. I've written about capacitance versus voltage and harmonic distortion in various dielectrics at http://www.cliftonlaboratories.com/capacitor_voltage_change.htm Will revisit this in the future with some RF data. Jack K8ZOA Ignacy wrote: disc ceramic capacitors - bad for IMD! If there is a problem with those capacitors at 30dbm, I am wondering about the power amps especially SS where ceramic caps are used extensively. Seems nearly all amp's IMD cam generated in those caps. Am I missing something? Ignacy ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [K3] [Elecraft] Questions about ARRL review
Ignacy wrote: If there is a problem with those capacitors at 30dbm, I am wondering about the power amps especially SS where ceramic caps are used extensively. Seems nearly all amp's IMD cam generated in those caps. Am I missing something? I suspect that when used in power amps any IMD products produced by ceramic capacitors will be masked by the IMD products generated by the active devices, be they tube or solid state. In a receiver the difference between the level of a given IMD product generated by an active device and the level of one of the 'parent' signals involved is much greater than it is in the majority if not all power amps, which means that any IMD contributed by passive devices can in some cases affect performance. It is the NPO disc ceramics that I have found to be troublesome when used in crystal filters and / or RF tuned circuits. Instead I use AVX's AQ12 multilayer ceramic chip (SMD) capacitors which are rated for use at microwave. Jack, I look forward to seeing your RF data. 73, Geoff GM4ESD ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [K3] [Elecraft] Questions about ARRL review
Thank you Lyle. It never occurred to me that this was purposeful. I adjusted the filter offsets with the 500 and 200hz filters to more closely center them. Guess I'll believe the factory settings from now on! tnx, Gary W7TEA This asymmetry is due to the way in which the K3 aligns the roofing and DSP filter passbands. The signal is not necessarily centered in the roofing filter passband; rather, the signal is shifted towards an edge to maximize the use of the roofing filter's skirt selectivity. -- View this message in context: http://n2.nabble.com/Questions-about-ARRL-review-tp1583996p1586332.html Sent from the [K3] mailing list archive at Nabble.com. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
