Pat,
I agree that using a single tube makes more sense. You still may have a
performance issue on 10M but if you are careful maybe not. The bottles I
used were pulled from navigational aid sites but I think broadcast
transmitters used them too. They pull them after a period of time. Or if
the emission is down. There is still plenty of power for amateur use. I
know the 3-1000Z was used in commercial amps because I have one in my
basement. This tube is harder to find.
I used to know more about this stuff. But I forgot.
Happy Christmas everyone!
-Robby
VY2SS
From: Pat Barthelow [mailto:aa6eg@hotmail.com]
Sent: Sunday, December 23, 2007 1:03 PM
To: robby@route2.pe.ca; amps@contesting.com
Subject: RE: [Amps] What is the best way to run a pair of 4-1000 tubes
Another question(s) re 4-1000As. I see them pretty regularly at ham swap
meets, used and cheap. Often with the carbon coated brown "tint" on the
inside of the envelope. Does anyone know what the likely commercial
application is/was, that pulls, floating around the ham community were used
in? Military? Broadcast radio? What was the Pulse application?
Someone mentioned in the past, that Broadcast TX's that used to yield
4-1000A pulls, have evolved towards solid state finals, and the supply of
pulls, has/is drying up.
Is the carbon deposit an indication of extreme age or hard running, and
probable near-end of life issues? Or, can it exist, and the tube still be
used in Amateur Service, happily ever after? What are the likely failure
modes for the 4-1000?
Did the 3-1000Z ever have a commercial application?
If the pulls have been sitting around for years, or decades, are they
subject to
the gas ingestion problem across their pin seals, over time of stored,
non-operation? Can you condition them with heat, but reduced B+ to degass
them?
I havent looked for one, but is there usually a manufacturer's date code
printed somewhere on, or in the tube?
BTW, I have an Eimac, aluminum SK-5?? air blower socket for the tube,
surplus to my needs, in case anyone is looking.
Merry Christmas,
All the Best, 73,
Pat Barthelow aa6eg@hotmail.com
http://www.jamesburgdish.org
Subscribe: http://bambi.net/jamesburg.html
Jamesburg Earth Station Moon Bounce Team
> From: robby@route2.pe.ca
> To: amps@contesting.com
> Date: Sun, 23 Dec 2007 12:34:06 -0400
> Subject: Re: [Amps] What is the best way to run a pair of 4-1000 tubes
>
> I built a grounded grid amp a few years ago....um..I guess 20..and used a
> pair of 4-1000PRs. I built it with RTTY contesting in mind. I used a
> separate filament transformer and B&W filament choke for each tube and had
a
> second blower that could be brought on line for RTTY. A pair of Hammond
795
> transformers in the P/S. It loafed at the limit on the low bands.
>
> Unfortunately, even though I built it in a big box and was very careful
> about stray capacitance in the output, I saw greatly reduced output on 10
> meters and also on 15. The output capacitance of these tubes is far beyond
> what is necessary to resonate on the upper HF bands and still see the
proper
> plate load impedance. 7.6pf per tube for a total of 15.2 on the pair. I
> assume this is because the screen grid is in very close proximity to the
> anode.
>
> But boy did it like 40M! It is currently sitting idle at VE7ZZZ.
>
> Get a triode if you want a GG amp. The 3-1000Z has 0.12pf per tube.
>
> If you are stuck on using the tetrodes, and want 10 and 15 meters I guess
> you need to run them in another configuration.
>
> I often wondered what would have happened if I had let the screens float.
> Or tied them to the anode. Something bad probably.
>
> -Robby
> VY2SS
>
>
> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of amps-request@contesting.com
> Sent: Sunday, December 23, 2007 11:17 AM
> To: amps@contesting.com
> Subject: Amps Digest, Vol 60, Issue 34
>
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