[Amps] 4-1000A in LK2000

Dave white mausoptik at btinternet.com
Fri Jul 3 14:47:03 PDT 2009

I assume this is a GG amp?  In which case the 4-1000 will do a great job.  >From memory I think its drive impedence in GG cathode driven  is around 200 ohms.  I'd just experiment with the tuned input a bit.  Driving my old 4-1000 amp with 100 watts from a Ten Tec Omni V which is a bit fussy about swr gives me about 1400 - 1500 watts out, again from memory because I've not used it for a while.  Mine has a simple band switched pi input matching network that has never given any trouble even with solid state drivers.  I use 6kv on the anode from a humungous transformer that's probably good to run a pair of those tubes in ICAS service.  So far I never blew up a tube, though I don't see many around at fleamarkets these days.  

Hope this helps.  Buy the amp, you'll find it a lot more reliable than modern kit using things like 8877s


Dave G0OIL

-----Original Message-----
From: aborg <a_borg at yahoo.com>
Sent: 03 July 2009 19:20
To: Amps at contesting.com <Amps at contesting.com>; Kevin LaHaie <klahaie at centricata.com>
Subject: Re: [Amps] 4-1000A in LK2000

I have a homebrew 4-1000A amp I built a couple of years as well. I standing by for the source of 3-1000Z tubes as well.

a_borg at yahoo.com

--- On Fri, 7/3/09, Kevin LaHaie <klahaie at centricata.com> wrote:

> From: Kevin LaHaie <klahaie at centricata.com>
> Subject: [Amps] 4-1000A in LK2000
> To: "Amps at contesting.com" <Amps at contesting.com>
> Date: Friday, July 3, 2009, 1:56 PM
> 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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