[TowerTalk] Re: [Amps] Relays for RF switching

[Tom Rauch]

> 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.

As for the tube connections, current is pretty low at the
anodes and is split between the tubes. Same in many portions
of the switching system. In areas where current is high, ETO
is smart enough to flood the braid with solder. This
eliminates the hundreds of small low-pressure connections
that RF current must flow through.

(Remember what RF does, skin effect forces current to the
outside surface of the braid and even to the outward surface
of the round conductors in the weave. The rest of the copper
might as well not be there. When a conductor exits the
outside and weaves inside, the impedance become much higher
because magnetic flux density is higher, so the current
flows over to the conductor exiting the weave to the
outside. It is all these hundreds and thousands of pressure
connections and the very small surface area carrying current
(the outer edge of each round conductor) that makes braiding
so poor.)

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.

73 Tom