Actually, 5V @ 30A same as a pair of 3-500z's which are 15A each. I used a
filament transformer from a SB220 to light my 3CX1000A7 160m amp. Any of
the SK-800 series sockets can be modified to remove the screen grid bypass
and use them with a 3CX1000A7. If I recall, the 3CX1000A7 was a external
anode ceramic replacement for the 3-1000z. The thoriated tungsten filaments
were brutes, you could drive them very hard and being instant on, there
wasn't much danger of stripping the cathodes like 3CX1500A7's. They draw
more grid current than a lot of other tubes draw plate current!!! I was
going to use them for my VHF amps until I played with the new generations
of SSPA's. That decision was a no brainer!! Someday I'll sell my collection
of tubes, sockets and chimneys to someone for paper weights!
Terry Price - W8ZN
Directive Systems and Engineering
703-754-3876
On Mon, Feb 8, 2021 at 12:27 PM Ron Rogers <ww8rr@charter.net> wrote:
> Not to mention that the 3CX1000a7 tube requires 5 volts at 50 amps just to
> light the filament…..same as a pair of 3-500Zs. That's 250 watts consumed
> by the tube just to get it to "light up".
>
>
>
> And Terry, since you mentioned the Eimac triode breach lock socket
> (SK-860)…….if you can even find one of those they will cost you $300-500.
>
>
>
> Ron
>
> WW8RR
>
>
>
> *From:* Moon-net [mailto:moon-net-bounces@mailman.pe1itr.com] *On Behalf
> Of *Terry Price via Moon-net
> *Sent:* Monday, February 08, 2021 11:57 AM
> *To:* Edward R Cole
> *Cc:* Byron Tatum; Moon-net Amateur Radio Moonbounce
> *Subject:* Re: [Moon-Net] Bob Sutherland 3CX1000A7 VHF Amplifier
>
>
>
> Ed,
>
>
>
> A 3CX1000A7 is NOT an 8877, a 3CX1500A7 is. Two COMPLETELY
> different tubes, different sockets, they are more like a 4CX1000A7 which is
> a breech lock socket. A 8877 is an indirectly heated cathode and a
> 3CX1000A7 is a directly heated cathode, like a 3-500z. Drive requirements
> and input/output capacitance are different. I've built a 3CX1000A7 amp
> using the classic W6PO 2m output tank but the input is much different.
> There was even a design using a 3CX1000A7 on 432 but it had poor
> efficiency and required lots of drive.
>
>
> Terry Price - W8ZN
>
> Directive Systems and Engineering
>
> 703-754-3876
>
>
>
>
>
> On Mon, Feb 8, 2021 at 11:43 AM Edward R Cole via Moon-net <
> moon-net@mailman.pe1itr.com> wrote:
>
> Byron,
>
> Bob Sutherland was W6PO, who's 3CX1000A7 (8877) amp is a classic design.
> Here is the link to my 2m-8877 project which I used for several years on
> eme (sold in 2018).
> KL7UW 8877 Amplifier page <http://www.kl7uw.com/2m-8877.htm>
>
> There was a company making them at one point (do not know if they still
> do). Maybe someone else on this list can assist you on that. I have the
> original document as reprint of Eimac Amateur Service News letter in the
> form of a MHTL document which I could send as attachment by direct e-mail
> (not thru Moon-net).
>
> The output circuit of my amp is stripline modification done by Harry
> WA4OFS (sk) who made the RF parts for my amp as a kit.
>
> 73, Ed - KL7UW
>
> At 06:35 AM 2/8/2021, Byron Tatum via Moon-net wrote:
>
> Hello-
> A long shot here. I am looking for info on a 3CX1000A7 VHF amplifier
> by Bob Sutherland (and two other authors in second article) that appeared
> as a 2 part article in March 1969 HR Mag page 6 and April 1970 page 26.
> What started my inquiry was discovery of a plate line assembly from the
> estate of a well known Collins engineer JB Jenkins W5EU. I recognized the
> assembly as from this 2 part article of which I have studied in past.
> Mostly for the sake of historical reasons, and learning, I am asking these
> things:
> 1. Does anyone have a copy of the full set of plans that are
> offered by contacting Bob Sutherland at Eimac as referenced in March 1969
> article? I surely would like to have a set to go with this plate line
> assembly.
> 2. Does anyone know if any of the complete amplifiers as offered
> by Al Roach W6JUK of Dymond Electronics were ever produced? This is
> referenced in the April 1970 article adjacent to the picture of the
> modified Henry 2K amplifier (modified by Bob Sutherland at Eimac to
> incorporated 3CX1000A7 RF deck using Henry power supply).
> I am curious about the history of this 2 part article and if there are
> any pieces of equipment that survived from it. I don't believe I would care
> to duplicate the complex output coupling scheme and mechanics but it is
> interesting to study. I would like to try and find a copy of the
> construction plans to go with this plate line assembly.
> Thanks,
> Byron W5FH
> 936-349-6353 cell
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
> 73, Ed - KL7UW
> http://www.kl7uw.com
> Dubus-NA Business mail:
> dubususa@gmail.com
>
> _______________________________________________
> Moon-Net posting and subscription instructions are at
> http://www.nlsa.com/nets/moon-net-help.html
>
>
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