Date : Tue, 10 Aug 2010 19:00:26 +0200
From : rick@... (Rick Murray)
Subject: Free Stuff Tranche III [Results]
On 10/08/2010 17:14, Pete Turnbull wrote:
> It's also why some older hand-drawn boards use curves instead of
> straight lines. [...] I had a UHF amp that used trimmed coax as
> part of the filter).
I used to fiddle around with old valve and transistor equipment before I
could afford something that wasn't more outdated than my sense of
fashion... ;-) ...and, really, some of the bizarre things in there must
have surely been the result of incense and lengthy incantations to the
relevant gods. One of my favourites was an old valve amplifier with a
thick piece of copper sticking straight out of the... I can't call it a
board, it was like waxy paper with point-to-point enamelled wire hooking
it together. Anyway, this piece of copper (like an earth wire, heavy
duty stuff) was dead straight except for two kinks. One about a third of
the way along, and one near the end. The kinks looked like the copper
had been bent over a biro.
I unsoldered this and put it aside, after measuring exactly where it
went in, and then tried all number of different types of pieces of
copper wire. Kinked, unkinked. I'm not sure what the heck a bit of
copper is supposed to do in an amp (it wasn't a radio!) or what
significance the kinks played, but it ranged from dead to severely
muffled-sounding. Kinks in different places in the wire seemed to be
like fiddling with a powerful tone control. Eventually I put the
original back, and spent ages getting it back as I measured it. And it
worked once again.
Really don't understand what was going on, but it certainly made me
appreciate the power of the unseen, for meters and 'scopes can tell you
what's happening on the wires, but only gives the vaguest hint as to
what is happening between them.
Best wishes,
Rick.
--
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
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