I just thought a pair of 3-500Zs, properly used, even at full legal
output, could also deliver a lifetime of service. My L-4B's 3-500s have
been delivering since 1965....in recent years, even in Contest Mode.
I think the number of on/ off cycles has a big effect in tube life times.
I know of a TL-922A in the MARS service which delivered it's full rated CW
power in Key Down 100% service, 24 hrs/day for 10 years... I have to say,
I was really suprised at that......
73, DX, de
Pat, AA6EG/N6IJ;
aa6eg@hh.tmx.com;n6ij@hotmail.com
599 DX Drive, Marina CA 93933
See us on the web: www.polkinghorn.org/n6ij
"The Contest Station from the Government"
On Mon, 4 Oct 1999, Alek Petkovic wrote:
> Hi Pat,
> The answer to your question is Economics.
>
> Running legal power with 4 tubes rather than 2, means you would probably
> never need to buy replacement tubes. 4 tubes should give a lifetime of
> service under those conditions.
>
> 73 de Alek.
> VK6APK
>
>
> At 07:02 PM 10/03/1999 -0700, Pat wrote:
> >
> >Hi Larry,
> >
> >Why would you want 4 x 3-500Zs? Two will do max legal power nicely...
> >
> >73, DX, de
> >Pat, AA6EG/N6IJ;
> >aa6eg@hh.tmx.com;n6ij@hotmail.com
> >599 DX Drive, Marina CA 93933
> >See us on the web: www.polkinghorn.org/n6ij
> >"The Contest Station from the Government"
> >
> >On Sun, 3 Oct 1999, Larry Molitor wrote:
> >
> >>
> >> At 11:39 AM 10/3/99 -0500, you wrote:
> >> >
> >> >About:
> >> >
> >> >"I am building an amp with four 3-500Z using low bands only (160 and
> >> >80m).
> >> >I do have two filament transformers, 5V/80A w/o a center tap on the
> >> >secondary coil. The other one contains four coils with 5V/25A ea. coil
> >> >also
> >> >w/o any center taps on the secondary side." (Etc.)
> >> >
> >> >How about connecting a small "audio" or "power supply" choke from each
> >> >side of the secondary to "eventual" ground? Calculate the inductance
> >> >value of them so that they will only allow a negligible (AC) current
> >> >flow to ground while maintaining a balanced condition for all voltages
> >> >involved in the circuits. I think reasonable sized, cheap chokes may be
> >> >possible but must have low DC resistances. Maybe from junk box.
> >> >
> >> >73, Roy K6XK
> >>
> >> I use a small filament transformer with a secondary center tap. Connect the
> >> secondary across the big transformer secondary. Leave the primary open. Use
> >> the small transformer secondary center tap for your cathode return.
> >>
> >>
> >>
> >> 73,
> >>
> >> Larry - W7IUV
> >> w7iuv@arrl.net
> >> http://www.axtek.com/w7iuv
> >> Amp pix at http://207.108.137.61
> >>
> >>
> >>
> >> --
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> >>
> >
> >
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