On Apr 4, 2004, at 7:32 AM, Gudguyham@aol.com wrote:
In a message dated 4/4/04 10:19:29 AM Eastern Daylight Time,
jaking@es.co.nz
writes:
How much can you safely miss match tubes? Does this extend so far
that one could run an different brand tube, Ie an RF parts 3-500ZG-RF
or a
Taylor 3-500ZG with and Eimac 3-500Z?
Hello Jeff, have a look at the tube, I will bet that the pin came
unsoldered
from heat and sparking occurred in between the tube pin and the outer
pin.
The sparking causes an insulation type deposit between the inner pin
of the tube
and the outer pin. If you can generate enough heat to remove the
outer pin,
clean it up and the outer pin and re-silver solder the pin back on,
the tube
may still be good.
However, the old solder is Pb-Sn (lead-tin), which should not be
mixed with silver solder, so first remove the old solder with
solder-wick before flowing in silver solder. Also, in this application
use rosin-flux, and not HCl-based acid-flux,
Take an ohmmeter on lowest scale and measure the filament
resistance using the tips of the probe underneath the isolated base of
the tube
where the pin emerges from the glass. Read the resistance of the
filament,
it should be about .6 ohms. If it is, then measure the resistance
using the
pin. If it is higher, that proves the connection of the tube pin to
the outer
pin is bad. You may be able to save the tube if you can resolder the
connection after you clean up the sparking deposits. Good Luck and
let us know. As
far as the mixing of tubes, Perhaps the 2 mismatched will work OK,
maybe it
won't. Try it out and see what happens. That is the only real test.
I do not see
any problems with testing them, the only thing that can happen is that
less
than optimum performance will be realized. You may be surprised that
it will
work just fine! 73 Louie
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Rich Measures, AG6K, 805.386.3734. www.somis.org/
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