On 21/03/15 05:00,
"Jim Thomson"<jim.thom@telus.net>wrote:
properly designed system would have a sump where the water would
naturally separate from the oil, and a valve to drain the small
amounts of water collected over time.
No. A properly designed system won't have a single pin-drop of moisture
in it to begin with, and if it did, a refrigerant drier would remove it.
### The problem with oil immersion...which is used on some eimac tubes per the
Eimac catalog is..... if you install a metal tub surrounding the tube... you
now have
stray C from the enclosure to the the anode....which can affect the PI net on
the
upper bands. RF parts used to sell a metal chimney..with a teflon ring on
top, for
the 3CX-3000A7 tube..for air cooling. It added 10 pf of C.
Tube is 24 pf from anode to grid, measured on a wooden bench.
And when inserted in the socket, rose to 33 pf.
That extra 9 pf is caused by the proximity of the lower anode fins to the
chassis below.
Once the metal chimney was installed, it rose to 43 pf.
Thank you for that. I had a quick google, but did someone want to offer
an opinion (or better) that such a metal chimney or (container/tub)
might make a 6m amplifier infeasible?
The increased dielectric constant of the oil will also act to increase
that capacitance.
If the Eimac thought it was appropriate to use a metal ring in close
proximity, then likely it was usable for I to do it as well.
It also seems, there may be the opportunity to entirely and safely
encapsulate the HT
## any oil cooling scheme would involve the use of an external oil pump +
external air
cooled radiator. ANY leaks anywhere, and you end up with a real mess on your
hands
Of course. But there are quality crimp fittings available everywhere.
I'd also have a drip tray under the tube sockets. In the end, it's a
nice clean-smelling quality oil. It isn't dog shit.
Steve
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