Date: Thu, 27 Oct 94 04:30:21 PDT From: Ham-Homebrew Mailing List and Newsgroup Errors-To: Ham-Homebrew-Errors@UCSD.Edu Reply-To: Ham-Homebrew@UCSD.Edu Precedence: List Subject: Ham-Homebrew Digest V94 #317 To: Ham-Homebrew Ham-Homebrew Digest Thu, 27 Oct 94 Volume 94 : Issue 317 Today's Topics: go through Impedence matching? (2 msgs) Send Replies or notes for publication to: Send subscription requests to: Problems you can't solve otherwise to brian@ucsd.edu. Archives of past issues of the Ham-Homebrew Digest are available (by FTP only) from UCSD.Edu in directory "mailarchives/ham-homebrew". We trust that readers are intelligent enough to realize that all text herein consists of personal comments and does not represent the official policies or positions of any party. Your mileage may vary. So there. ---------------------------------------------------------------------- Date: 27 Oct 1994 05:46:21 GMT From: testing@ucsd.edu Subject: go through testing ------------------------------ Date: 27 Oct 1994 05:47:58 GMT From: ian.mitchell@research.utas.edu.au (Ian Mitchell) Subject: Impedence matching? ------------------------------ Date: 27 Oct 1994 05:51:32 GMT From: ian.mitchell@research.utas.edu.au (Ian Mitchell) Subject: Impedence matching? >Hmmmm... maybe you can help us all out and measure the phase noise of >this receiver. The HC4046 VCO is reputed to be quite noisy; are you using >the on chip VCO or an off-chip VCO. Firstly, let me thank all those who replied to my original post. Most helpful. In answer to the above question, I will be using the phase comparator only. With either output 2 or 3, not the XOR only output, since the divided LO signal will not be a 50% duty cycle. Ian ------------------------------ Date: Wed, 26 Oct 94 18:13:14 GMT From: rdewan@uhura.cc.rochester.edu (Rajiv Dewan) References<1994Oct24.130552.523@ke4zv.atl.ga.us> , <38limd$r4n@longwood.cs.ucf.edu> Subject: Re: SWR between transmitter and amplifier In article <38limd$r4n@longwood.cs.ucf.edu> clarke@longwood.cs.ucf.edu (Tom Clarke) writes: >In article tom_taylor@taligent.com (Tom Taylor) writes: >>I recently finished building a homebrew two tube 4-400 grounded grid >>amplifier for 80-10 meters. It works great. However, I didn't build >>a band-switched tuned input circuit. Without it, the input impedence is >>approximately 50 ohms... but not exactly. I'm driving the amp with > >I would say that as long as the coax between your exciter and the >amplifier is less-less than a wavelength, that you have a tuned ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >circuit on the input of your amplifier - the output tank/matching circuit >of the exciter. The coax then acts like a lumped RLC as far as >the excitor and amplifier are concerned and the coax RLC are tuned >out by the exciter. Length matters in two ways here: - attenuation. In this case, shorter the coax the better - transmission line transformer: here the relationship is non-monotonic. For instance, going from 3/8 to 1/2 wave in coax electrical length will will result in "less" impedance tranformation from input to output even though the coax is longer. Rajiv aa9ch ------------------------------ End of Ham-Homebrew Digest V94 #317 ******************************