A valid point however most anything that will accept a silver plate is usually aceptable , copper tube is excellent
>From: "Eric Lemmon" <[EMAIL PROTECTED]> >Reply-To: [email protected] >To: <[email protected]> >Subject: RE: [Repeater-Builder] Re: 6M cans made from other metals >Date: Mon, 25 Dec 2006 17:36:58 -0800 > >Before we get too far into a discussion of what metals *can* be used to >fabricate a duplexer, on 6m or on any other band, we should perhaps >consider >what metals *should* be used for that purpose. > >If we examine the basic differences between cheap duplexers that drift all >over the place and become noisy in a short time, and expensive duplexers >that are rock-stable and noise-free for years, we find that they boil down >to just a few: Materials used in construction and workmanship. > >An ideal duplexer is made of materials with complementary coefficients of >expansion, meaning that as the outside body of the cavity expands and >contracts with temperature changes, the inner elements move in such a way >that the tuning is not affected to any significant degree. Before you >conclude that your duplexer doesn't need any fancy temperature compensation >because it is in a temperature-controlled radio room, think again- ambient >temperature is only part of the picture. Let's suppose that you have a 125 >watt transmitter feeding a six-cavity duplexer that has a typical insertion >loss of 2.2 dB. That power loss of 2.2 dB equates to about 50 watts that >is >consumed as heat in your duplexer, and you can bet that the duplexer >components will start moving on long transmissions. > >If a poorly-made duplexer is subjected to constant cycles of heating and >cooling, the contact surfaces will wear and sparking will occur since the >movement is happening while transmit power is applied. High-quality >duplexers have beryllium contact fingers working on a silver plating. The >interior of the cavity may also be silver-plated to increase the efficiency >due to skin effect. Cheap duplexers may have simple friction contacts made >of copper or brass. > >So, yes, it is possible to make duplexers from almost any metal that can be >brazed, welded, or soldered. However, combining diverse materials to make >a >duplexer that is effective, efficient, and stable can be a challenge. >YMMV... > >73, Eric Lemmon WB6FLY > > > > > > > >Yahoo! Groups Links > > > _________________________________________________________________ Advertisement: Fresh jobs daily. Stop waiting for the newspaper. Search now! www.seek.com.au http://a.ninemsn.com.au/b.aspx?URL=http%3A%2F%2Fninemsn%2Eseek%2Ecom%2Eau&_t=757263760&_r=Hotmail_EndText_Dec06&_m=EXT
