----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: "Michael Tope" <W4EF@dellroy.com>; "Geoff" <geoffrey@jeremy.mv.com>
Cc: <towertalk@contesting.com>
Sent: Saturday, April 17, 2004 8:21 PM
Subject: Re: [TowerTalk] Re: [Amps] Relays for RF switching
> > Amost all of the interconnects in the ETO Alpha 78 RF
> > deck are made with silver plated copper braid. Most of
> > them are flooded with solder so that they are essentially
> > rigid, but the connections between the tube anodes and
> > the plate choke are flexible braid (no solder filling) as
>
> The difference is important if braid size is limited. If you
> can use any size braid, then you just size up until the
> stuff doesn't melt.
> Replace the tank leads carrying full current in your ETO
> with loose braiding from RG-174 (or even loose RG58 shield)
> in the tank and tell us how it works on ten meters. You
> won't measure an efficiency change, because you won't have
> time to measure before it starts smoking.
If you're truly interested in reducing the losses and parasitic L, then you
could always look into Litz wire. It's available from specialty wire
companies like MWS (in Westlake Village, CA) and others. There's a
surprising amount of Litz wire being used in switching power supplies, as
the frequencies go up, and they try to eke out every last percent of
efficiency and squeeze it into ever smaller volumes. Aside from the basics
of Litz wire, which have been around for decades, there's some recent
technical literature on insulated multiple conductors in HF applications,
where they look at various braid patterns, multifilar wire, etc. all in
terms of size, manufacturability, etc.
For the amplifier kind of application (and "hookup wire jumper" too), I
think that flat strip would probably be your best bet. It is flexible.
For the "relay contact" application, where it's going to have to move
thousands/millions of times, I think using relay designs that don't have
flexing conductors would be more appropriate. In high power contactors (as
in air conditioners, and motor starters), they essentially drop a bar across
two contacts with the electromagnet. No moving or flexing wires required.
This is also the general design used in a number of RF switches (since the
bar can be designed to be a stripline with controlled impedance).
_______________________________________________
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Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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