[Boatanchors] Diode replacements for 866 tubes, ratings needed ?

[Rob Atkinson]

I've never owned a Warrior but I have heard about them and a friend has one
and I have had a chance to look it over (although I don't recall much about
the specific circuit details).    My observation:  The Warrior was designed
and built at the tail end of the AM days when gear was designed and built
more for continuous duty.   It's a relatively big heavy brick compared to
modern ham RF amplifier products today.  Much is conservative with that amp
including the plate voltage.  This means you won't get 1.5 kw or even 1000
watts; maybe more like 500 or 600 watts out, but, it will sit there putting
out that power at 100% duty cycle with no time limit especially if you put
a small fan over the RF cage.   I'm told that for this reason, the amp is
sought after by vintage RTTY ops--the green key crowd.   There may be some
on this list.   I expect at the time it was marketed it was indeed a "legal
limit" amp--1 KW input in the U.S. (which should still be the legal limit
in my opinion).

I see you have wisely decided to avoid any big revisions to the plate v. so
this comment is for general consumption.   I don't wish to seem pedantic
but if it were me and I wanted to run more power but at 50% or less duty,
I'd pretty much leave the Warrior alone and sell it and look for a SB200 or
SB220.

73

Rob
K5UJ


On Wed, Nov 12, 2014 at 9:57 PM, Rick Poole WA1RKT <wa1rkt at comcast.net>
wrote:

>
> Good evening, Rob.
>
> Never had any thoughts about doing that.  At one time I did consider
> keeping the full wave center tapped transformer but replacing all of the
> filter components with a capacitor bank.  This would have resulted in a
> higher voltage than leaving things as is... theoretically as much as 2400
> volts which would be well in excess of 811A ratings (most or all of the
> modern-day amps using 811A tubes already exceed the tube's maximum plate
> voltage rating) but comfortably within the 572B's rating.  But, regulation
> will suffer.  The whole idea behind a swinging-choke input is that the
> choke inductance goes down with a rise in current drain, so that at higher
> current drains the filter begins to look more like a capacitor-input
> filter, improving regulation.
>
> Current plan is to leave things as they are except for replacing the 866A
> rectifiers with solid state.  We'll see how that works.  Hopefully the
> transformer, choke, and filter cap are all in good shape... we'll see about
> that, too.
>
> Rick WA1RKT
>
>