Yep, I would rate the Eimac 3-500Z tube today's best bang-for-buck / dollar per
watt legal limit SSB amplifier tube. A present day production 3-500ZG graphite
anode pair of 'em from the better China manufacturer sourced thro' RF Parts or
Greenstone remain reasonably priced and affordable.
Next best and very capable but more expensive triode at now eye-watering
pricing is the 8877 / 3CX1500A7. The Chinese made Greenstone versions are more
reasonably priced but still expensive.
Leigh
VK5KLT / VK5LT
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of David Gow
Sent: Friday, 3 December 2021 3:08 PM
To: gudguyham@aol.com
Cc: amps <amps@contesting.com>
Subject: Re: [Amps] Triode Amps
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 an easy legal limit for SSB and CW. .
On Thu, Dec 2, 2021 at 2:45 PM gudguyham--- via Amps <amps@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@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@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@contesting.com] On Behalf Of Peter
> > Voelpel Sent: Thursday, December 2, 2021 4:16 PM
> > To: 'Kim Elmore'; amps@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@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
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
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