[Amps] Triode Amps

[David Gow]

3-500z  Eimac Data Sheet  says Typical Operation 890 watts useful power
output CW or PEP with 3500 volts on the plate.  Maximum plate voltage 4000
volts.  Henry ran them at 4000 on the 3KA.  I had one with a pair and it
would  do 2000 watts out into a commercial big dummy load and loafed at
1500.  Henry pushed them hard but still within Eimac maximum specs. Copy of
Data sheet is yours on request.  The limiting factor on a 3-500z amp is the
power supply and cooling.  The Eimac data sheet specifies Eimac air sockets
and chimneys.  Not for RTTY, FT8 or AM but a neasy legal limit for SSB and
CW. .

On Thu, Dec 2, 2021 at 2:45 PM gudguyham--- via Amps <amps at contesting.com>
wrote:

> The Palstar version of Commander was always   Don Kessler.  There was
> about one full run of the line sold and I don’t believe the second run ever
> went into production.  I have two of the Palstar 2500’s and I had an issue
> and got no satisfaction.  WE are pretty much alone and are going to have to
> fend for ourselves.  I haven’t checked the schematic but you can sure use a
> generic transformer for the filaments.  There are tons of 12.6v
> transformers out there that with a little to no tweaking of the primary
> voltage you can land 13.2volts on the three filaments total.  If you use a
> 12.6. 4 amp rated transformer on 1 tube, the filament voltage will be spot
> on.  For 3 tubes you’ll need a 12amp 12.6v transformer.  If it’s a tad
> higher you can tweak the input voltage with a high wattage chassis mount
> resistor.   The other option is to see if an old 2500e transformer is
> kicking around.  I assume you have throughly tested that transformer before
> you condemned it?
>
> Sent from the all new AOL app for iOS
>
>
> On Thursday, December 2, 2021, 5:08 PM, AJ <iamfromcanadaalso at gmail.com>
> wrote:
>
>
>
> My current issue is with a Palstar 2500E which is a totally different
> beast compared to the previous Commander versions. Only a handful of
> them made according to Paul.
>
> It has three 3CPX800A7's in it. The plate transformer is twice the size
> of the early Commander 2500E.
>
> So make a long story short. . .
>
> Filament trans primary open.
> Filter caps bulged.
> Diodes shorted
> Tube filaments open
> Step start contacts welded.
>
> I have yet to test the plate transformer, I do not have any specs on
> it. There is no part number on it. I have contacted Paul at Palstar he
> has no info as that product line was sold.
>
> I have sent and e-mail to the owner (not positive if I have the correct
> persons info) of the Palstar design; nothing back as of this time.
>
> If anyone on here knows how to contact the current owner of the Palstar
> design please let me know off list.
>
> Thanks AJ___ VE3HJ
>
>
> On Thu, 2 Dec 2021 16:19:09 -0500
> "Tim Duffy" <k3lr at k3lr.com> wrote:
>
> > My favorite triode for 1500 watts all day is a single 8877. 4KV and
> > 30 watts drive.
> >
> > Used 8877s exist and are more than capable for long lives. Some of
> > the 8877s at K3LR have date codes from the 70s... still going strong
> >
> > 73
> > Tim K3LR
> >
> > -----Original Message-----
> > From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Peter
> > Voelpel Sent: Thursday, December 2, 2021 4:16 PM
> > To: 'Kim Elmore'; amps at contesting.com
> > Subject: Re: [Amps] Triode Amps
> >
> > Eimac specifies 890W for a single tube at 3.5KV plate voltage and
> > 740W at 3kV.
> >
> > 73
> > Peter, DJ7WW
> >
> > -----Original Message-----
> > From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Kim
> > Elmore
> >
> >
> > The 3-500Z is an excellent tube, but 1500 W isn't reasonably
> > available out of a pair, even at increased plate voltage
> >
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