Re[4]: [HomeBrew] UHF SWR meters

Mon, 23 Feb 2004 13:21:03 -0600

Hello Steven,

I'm sure I have that somewhere around here in a 1978 handbook, but I
can't locate the book at the moment. The 2000 handbook didn't have the
copper pipe DC (or I didn't see it there). I don't remember seeing the
wire-under-braid one in the '78 or later books. For the stripline
method, I'm not sure yet what PCB materials I have available
(thickness, dielectric constant, etc) to calculate the width and gaps
of the striplines (or how much that matters).

Monday, February 23, 2004, 12:43:22 PM, you wrote:

SW> ** Please do NOT cross-post messages to multiple mailing lists on the "To:" or "CC:" line of the e-mail message. **

SW> Hello Elliot,

SW> I'm new to this list..

SW> The ARRL Antenna handbook has plans for a VHF/UHF directional coupler made
SW> from common copper pipe couplings, but looks like a project. 

SW> I have an old (1968) VHF handbook with an interesting VHF/UHF bridge. It
SW> uses a 7 1/2" lenght of RG-58 with a pick up wire inserted between the
SW> braid and center conductor. A 47 ohm resistor is placed at the exact center
SW> of the pick up wire to ground, and the froward/reverse detectors are on the
SW> opposite ends of the pick up wire. (and come out from the shield a little
SW> before the ends of the coax)  It's claimed to work from 50 to 450 MHz. If
SW> you only want 430 operation, you could shorten the length of the coax by at
SW> least half. 

SW> The main trick is feeding the pick up wire between the shield and center
SW> conductor. Remove the outer jacket of the coax, lossen up the braid by
SW> pushing it towards the center and insert the pick up wire from the center
SW> point of the coax, leaving a small loop to attach the 47 ohm resistor to. 

SW> Finally, I would think you could make a coupler on a small piece of printed
SW> circuit board stock using strip line techniques. 

SW> 72,
SW> Steve, KD1JV
SW> "Melt Solder"
SW> White Mountains of New Hampshire
SW> http://www.qsl.net/kd1jv/
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-- 
Best regards,
 Elliott   N0UKF                      mailto:[email protected]
www.qsl.net/n0ukf/