[Amps] 4-1000A in LK2000

[Carl]

When was the last time you tested those tubes at full power?

What is the idle current?

A MFJ 259B will give you an idea which way the input network wants to go.

Carl
KM1H


Carl
----- Original Message ----- 
From: "Kevin LaHaie" <klahaie at centricata.com>
To: <Amps at contesting.com>
Sent: Friday, July 03, 2009 1:56 PM
Subject: [Amps] 4-1000A in LK2000


>I have a change to pickup up a good condition BTI LK2000 floor console
> amplifier.  It has the heavy duty power supply (but is not labeled as an
> HD), includes the DL-2000 dummy load so it is a complete example of this
> cool amp, and was built in 1969.
>
> This amp still has the original 3-1000z, and after all these years in
> contest service, it can still put out about a KW, but obviously well
> down from the factory specs. (I have the original documents that came
> with the amp)
>
> The documentation claims that the 4-1000a can be also be used, and I
> have a handful of them.  Per the manual, the only mod required is to
> shorten the plate cap a bit since the 4000 is a bit taller. I had a
> spare HC8 cap, so I performed the mod and tried several tubes, but my
> issue is high input SWR. The tuned input range is not adequate to
> provide a low input SWR, so the exciter only puts out about 50 watts,
> resulting in output power of only 3-400 watts depending on the band.
> Not acceptable.
>
> I haven't put it behind the trusty TS-830S with the Pi network in the
> finals, which would drive it fine, but that is not what I hope to use
> with this amp.
>
> Is the input impedance that different from the 3-1000?
>
> I was hoping to get decent performance with the stash of 4-1000a's I have.
>
> Does anybody know of a source for 3-1000z's?  If so, let me know.  It
> will influence my decision to acquire this amp.
>
> 73 Kevin K7ZS
>
>
>
>
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