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Re: [Amps] How to read the 3-500Z spec sheet?

Subject: Re: [Amps] How to read the 3-500Z spec sheet?
From: Bill Dzurilla <>
Date: Sat, 22 May 2010 14:54:55 -0700 (PDT)
List-post: <">>
Thanks for the reply, but I don't think I follow.

Guess I had interpreted the spec sheet as meaning that, if you configure the 
tube in class B grounded grid and apply HV of 2000v, you should expect to see 
400ma of plate current and 500 watts of peak "useful" output.

I am just trying to figure out if this homebrew amp, which does not have any 
manual or detailed info, is working as it should.  If the spec sheet means what 
I think it means, it seems the amp is in the ballpark.

73, Bill NZ5N
>Spec sheets don't know anything about load or no load. If it says for
>example, 3000 volts at 500 mA, that's what it means. 

>73, Bill W6WRT

--- On Sat, 5/22/10, Bill Dzurilla <> wrote:

> From: Bill Dzurilla <>
> Subject: How to read the 3-500Z spec sheet?
> To:
> Date: Saturday, May 22, 2010, 10:39 AM
> Hi,
> I'm looking at the spec sheet for the 3-500Z at
> At the top of the second pages, it gives numbers for
> various parameters at different levels of high voltage
> (3000, 2500, 2000, and 1500).  Are these voltages at
> load or no-load?  And how do Single-Tone DC Plate
> Current and Peak Envelope Useful Output Power correlate with
> key down plate current and output?
> The reason I ask is because I picked up a homebrew 6m amp
> with a single 3-500Z, which uses a power transformer from an
> SB-200.  Key down power output is 400w.  Assuming
> the amp's meters are accurate, no-load plate voltage is
> 2300v, and plate voltage under full load is 1950v. 
> Plate current with no drive is 100ma and plate current with
> full drive is .52a.  About 40 watts of drive produces
> the full 400w out.  Further increases in drive, up to
> 100w, do not increase output.
> Judging from the spec sheet's 2000v table, my guess is that
> the amp is performing as well as it can with this power
> supply.  I know that a converted AL-80B with a single
> 3-500Z can produce 900w or so on 6m, but it has a 3000v
> p/s.
> Do you think it would be OK to run this amp at the full
> 400w in WSJT (continuous carrier) modes?
> 73, Bill NZ5N 

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