[Amps] 4CX800 2 Meter Linear

[Steve Thompson]

On Monday 16 February 2004 01:40, Glenn McNeil wrote:
> Hi Gang..

>
> When I have max output, I'm looking at about 680ma Ip, very little in the
> way of screen current ( the needle hardly moves) and a big kick
> "backwards" on the Grid Meter...Yep, it attempts to go negative, and the
> more drive, the more energetic it becomes.Incresing drive see's more rf,
> but lots more Ip.

Not sure about what's happening with Ig1, but otherwise it reads as if the 
anode/plate load resistance is too low. Maybe the output coupling connection 
runs out of adjustment before getting to the right point. If the coax between 
the ouput socket and the fingerstock connection is short, you could try 
putting a quarterwave of 75ohm cable on the output so your 50 ohm load is 
transformed into 112ohms at the amp output which might give you a better 
loading range.

Steve
>
> A fellow Ham has one the same...and his works fine. I copied his
> construction details accurately ( I hope ) and the above is the result. My
> Amplifier learning curve is steep, and going more vertical. This thing is
> on wheels and I live on a hill...any ideas before I give it a push ??
>
> 73
>
> Glenn
> VK4TZL
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