Thanks, Skipp. I have full docs on the tube, including the data curves. I
also have the EIMAC "care and feeding" book, and their "tube performance
computer" is on the way now to me. I also have the manual on the Henry 4k-2
(5cx1500) amp, so I am not lacking for specifics on _normal_ operation of
the tube or general pentode amp design.
I had hoped to avoid much study on this project, and simply get this thing
working as-is in some fashion at minimal cost.
My next step is to hopefully power up to whatever degree is required to get
the supportive/protective circuitry operating so I can check those functions.
The RF deck is in a 19 inch wide drawer which "plugs in" to the 30 inch
wide supporting unit. I could possibly just grab components from the
supporting unit and build a new circuit I could understand, but it seems a
waste to do this, and also my design probably wouldn't be as good as TMC's.
Also the vac caps or tube might be gassy/unusable, so the project might
wind up just being a few more parts added to the junk box!
Last night I got out the tube performance curves and tried to understand
what currents would flow w/o drive. It appears to me that at a G1 bias of
-182 (what I measure there now) and G2 voltage of 800 (which might appear
there when the protective circuit works properly), I would have only 1-2ma
G2 current and only 7-8ma Plate curent at 1 KV, but I am concerned that
maybe I don't really know how to read these curves. Anybody want to have a
look at it to confirm if I scan it?
I should have mentioned a _long_ time ago this screen is rated at 175 watts
dissipation (G1 is 50), so maybe I shouldn't be worried anyway. I don't
think the screen supply would deliver that much.
Jerry W4UK
At 10:09 PM 11/16/2001 -0800, skipp isaham wrote:
> > In an old 5CX3000A 1.6-32MHz amp I am working on,
> > the plate blocking caps are rated at 8KV. Can I
> > guesstimate from this what plate voltage was intended?
>-
>I have worked on FM broadcast transmitters and Henry HF
>amplifiers using the 5CX1500A and B series tubes. If you
>want information about any of said, I can supply it.
>-
>Henry made (IMO) a dog of an HF amplifier using this tube,
>for a short time it was popular in Elcom Bauer and Sparta
>FM Broadcast Transmitters. Probably other brands used it.
>-
>The Sparta 602 is a long lasting unit running a tap selected
>output,high voltage supply is used to set the output power.
> From memory the thing would easily honk 2200 plus watts
>out on 95.3 Mhz a big 24/7 .
>-
>The tube can be rebuilt... I was told the A&B versions are a
>bit different, which includes separate socket requirements,
>but actual direct swapping worked in two VHF examples.
>-
>Gas is a big concern... I would give it at least an two to four
>hours warm up after a slow ramp to the rated min filament
>voltage. Depends on how long it's been idle.
>-
>This tube seems more sensitive to proper heater voltage than
>any other I've worked with. I would never apply screen voltage
>without something near the proper min anode potential.
>When its going full tilt, it is an incredibly bright light source.
>-
>Let me know if you need information from the paperwork I
>have here.
>-
>cheers
>skipp
>-
>
>________________________________________________________________
>GET INTERNET ACCESS FROM JUNO!
>Juno offers FREE or PREMIUM Internet access for less!
>Join Juno today! For your FREE software, visit:
>http://dl.www.juno.com/get/web/.
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
|