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From: michaelk@copper.UUCP
Newsgroups: net.audio,net.analog
Subject: Re: need interconnect cable recommendations...
Message-ID: <476@copper.UUCP>
Date: Sun, 13-Jul-86 23:40:10 EDT
Article-I.D.: copper.476
Posted: Sun Jul 13 23:40:10 1986
Date-Received: Mon, 14-Jul-86 19:53:49 EDT
References: <2107@orca.UUCP> <926@ihu1g.UUCP> <1225@uwmcsd1.UUCP>
Reply-To: michaelk@copper.UUCP (Michael Kersenbrock)
Distribution: na
Organization: Tektronix, Inc., Beaverton, OR.
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>> stuff is impossible to solder (read: BAD CONNECTION).  Finally, all RG-59
>> has a solid core, which, if you're concerned about skin effect, is decidedly
>> not the thing to use as an interconnect.
>

1) You might want to run the skin-effect program that I posted earlier. I
   wrote it for speakers but...use the impedance level in your interconnect
   instead of speaker impedence.  Skin effect will actually be even less
   than calculated because: only one lead is 22 Ga. in coax, the "return"
   lead is a good bit better.  I don't think you will find anything
   significant unless the (parallel) input  capacitance of your next
   stage is incredibly large.

2) Conductors being solid-core does not "hurt" skin effect wise. 
   At VHF frequencies (above 50 Mhz say) you can use a hollow tube
   and have the same impedance as a solid rod of the same diameter.
   Having copper in the middle doesn't hurt.  At low frequencies
   it helps.  

   Skin  effect is why RG-59 can be made with a copper-
   plated iron conductor.  RG-59 is primarily sold as TV cable (at RS)
   where the lowest frequency (channel 2) in the cable is over 50 Mhz
   (and channel 83 is MUCH higher).  
   

3) If you would like a lower-capacitance interconnect you might try
   RG-62 that has a mostly-air dielectric.  Depending where you get
   it, it costs little more than  RG-59 which is about the same size .


-- 

Mike Kersenbrock
Tektronix Software Development Products
Aloha, Oregon