This is an excellent thread to rat hole. Tnx to all commenters.
> On Jul 30, 2020, at 5:15 PM, john Parmalee via BVARC <bvarc@bvarc.org> wrote: > > An 811 is a tube from the 40s, I recall a Western Electric KW broadcast > transmitter that used a pair to modulate a pair. It was a brute. > > To my knowledge tube testers were not intended to test transmitter > tubes.maybe a TV fly back tube The way to test them is in a transmitter > noting the watts in and watts out. As a tube ages the filament may loose it's > emission. some times boosting the fulfillment a volt or two will squeeze a > little more life out of them, I used to work with a 50KW TV transmitter, a > new tube was under voltage on the filament and when it was finished a year or > so later it would be 10 to 15% over specs. > Another problem is gas that boils out of the plate, Carbon in this case. The > Thoriated tungsten filament is designed to absorb gas. just leaving the > filaments on for a week or so might remove gas. Sometimes you can see the > gas in the tube as a neon like flicker, > > The following test is not for those do not know how to work with with high > voltage, one hand in the pocket, stand back and more, they should run from my > advice about testing with 700 volts or so. > > To test a tube you might use a 700 volt supply and adjust it to the value in > the specifications First apply bias to the grid using a ma meter to monitor > both plate and grid. More negative bias means less plate current. This is a > DC test that does not account for what RF is asking the tube to do. Some > times a tube was unuseable in the final but would work ok for a while as a > modulator. > > K5VGM WI2XLJ > In a message dated 7/29/2020 2:15:55 PM Central Standard Time, > bvarc@bvarc.org writes: > > John, Fondren EPO's tube tester hasn't worked for years. They'd love to have > someone fix it - nice project for anyone intersted - call Chris. > > Gus, KG5OFB > > On Wed, Jul 29, 2020 at 9:02 AM John Mechura via BVARC <bvarc@bvarc.org> > wrote: > Greetings, > > Unfortunately my tube tester is too new to test this tube. I would recommend > contacting Chris at EPO, Electronic Parts Outlet, to ask him if his tube > checker can test this tube; if it is listed on his chart. He has a stand-up > tube tester such as would have been at drug stores of my youth. > > The 811 is a triode, utilizing a thoriated tungsten filament as a cathode. > As Rick suggests, an ohm meter check of the filament / heater should test for > continuity. Then check for shorts between filament, grid and plate, there > should not be any. Pins 1 and 4 are the filaments. Pin 2 is unused. Pin 3 > is the grid and the plate is on top. Look and see if the plate shows signs > of discoloration or overheating. If the silver getter coating inside the > glass is silver and not white then the tube is holding a vacuum still. > > The specs are here: > www.radiotechnika.hu/images/811A.pdf > > My e-mail is: > john.mech...@gmail.com > > 73 > > John, KI5HOC > > > > > On Tue, Jul 28, 2020 at 9:42 PM Rick Hiller <rickhille...@gmail.com> wrote: > Couldn't you simply just measure pin to pin and compare one tube to the > others? Find the odd guy(s) out that way. Then, stick them, one by one, > in the "tube testers" from Ameritron, the 811 or 811H. HI > > John, HOC, is the tube guy.....he will know....73...RH > > On Tue, Jul 28, 2020 at 9:18 PM Jimmy Vance via BVARC <bvarc@bvarc.org> wrote: > One of the guys in KARS needs to test a few 811's, does anyone have a > tester capable of testing these? > > > Thanks > --jv > na5d > > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > BVARC@bvarc.org > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > > > -- > Rick Hiller > e-mail: rickhille...@gmail.com > Cell: 832-474-3713 > Physical: 9031 Troulon Drive > Houston, TX 77036 > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > BVARC@bvarc.org > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > BVARC@bvarc.org > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org > > ________________________________________________ > Brazos Valley Amateur Radio Club > > BVARC mailing list > BVARC@bvarc.org > http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
________________________________________________ Brazos Valley Amateur Radio Club BVARC mailing list BVARC@bvarc.org http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
