Bertha used two ceramic vacuums, stood on end with the silver plated coil
between them (she's a mono bander). The caps were driven with right angle
drives and turns counters. That's why the turns counters are mounted so low
on the chassis. I still have a few right angle drives available and some
shaft coupler hardware, if anyone interested.If I can find them, there is a
large box of panel bushings too (see pic # 2),
NOTE: there is only ONE 15kV module still available now, and no more to
follow. 3-10 VDC in @28mA, up to -15 kV out.
Bertha can be seen at:
http://homepages.dstream.net/K0FF/Bertha.jpeg
Right angle drive etc.at
http://homepages.dstream.net/K0FF/rightangledrive.jpeg
HV module at
http://homepages.dstream.net/K0FF/HVmodule.jpeg
Happy building > Geo>K0FF
-----Original Message-----
From: jeff millar <jeff@wa1hco.mv.com>
To: AMPS <amps@contesting.com>
To: <amps@contesting.com>
Date: Thursday, September 14, 2000 11:33 PM
Subject: [AMPS] Mount pi-net capacitors vertically
>
>I went to the site mentioned a few days ago with all the amp pictures,
>http://www.angenent.org/W7IUV/amp-pix.htm and noted that most of these put
>the vacuum variables horizontal with the tuning shafts straight out the
>front panel. With all the talk about stray inductance and grounding, I'd
>like to ask why they all do this?
>
>I saw an amp by an anonymous fellow that seemed like a much better design.
>This baby used four 8877's in parallel grounded grid and two vacuum
>variables mounted vertically to the same chassis plate, right next to the
>tubes. The plate inductor jumped across the two standup vacuum caps. The
>tuning shafts went into the bottom chassis, through right angle drives and
>out to the front panel.
>
>The key advantage of this approach is excellent ground return paths with
the
>tradeoff being two right angle drives. This eliminated any seams in the
>ground returns.
>
>In general, it appears that amp builders don't worry much about seams. In
>looking over the pix, I saw tubes mounted on a plate that then mounted on
>the chassis with a few screws or caps mounted on the front panel with the
>front panel vaguely connected to the chassis, etc, etc.
>
>I could imagine all kinds of problems with feedback caused by loose screws
>or corrosion buildup in the multiple connections between the grounded end
of
>the caps and the grid of the tube. Just bump the case, jiggle the feeble
>connections through the chassis, the circulating currents find other routes
>around the chassis (like the input circuits) and _bang_.
>
>BTW, the amp cruised at 4 KV and 4A. The meter attached to a 10 KW Bird
>element slid smoothly up to the right and went tink on the pin. Very
>impressive, very clean design.
>
>jeff
>
>
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|
