> 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.)
Do you think the resistivity of the solder makes any
significant difference to the resistivity of the flooded
braid, Tom. When I rebuilt the RF deck in W6UE's
Alpha 78 (someone cooked the bandswitch big
time), I used the silver braid from RG-142 coax to redo
all the old braid connections. I had originally intended to
flood this braid with silver solder, but I may have used
the wrong stuff by mistake. The stuff I used appears to
be 95% Tin/5% Antimony (I have both kinds in my
shop and the two rolls look alike - hi). As it turns out,
however, even silver solder is mostly Tin (typically 95%),
According to the datasheets, the silver alloy solder
I have is only slightly more conductive than the
Tin/Antimony alloy I actually used (14% of copper vs.
12% of copper for the Tin/An alloy) [note: the conductivity
of SN63 Tin-Lead alloy is 11.6% that of copper).
Owing to its much higher resistivity, seems like the
overall conductivity of the flooded braid might be
negatively impacted if the solder was applied too
generously. Any thoughts on this?
73 de Mike W4EF............................................
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|