[Amps] drake l-4b from 4-400 to 3-500

[R.Measures]

On Aug 24, 2004, at 7:20 AM, DF3KV wrote:

>
> ----- Original Message -----
> From: "Partain, Chuck" <Chuck_Partain at maxtor.com>
>
>> i'm thinking now, it maybe a L4 not the B model..
>
>> maybe i just didn't pay attention...I've been busy with
>> too many projects. this was given to me to look at for a repair
>> (yes a friend ham) and was just curious on swapping this over.
>> the PS had bad caps(replaced) the diodes were replaced and also the
>> glitch resistor and a 5k 10w was cooked...that had been replaced. so
> some work
>> has been done..
>
>
> Hi Chuck,
>
> the L4 was equipped with 3-400Z and the L4B with 3-500Z.
> If you still get full output there is no need to swap the tubes,
> anyway both types will do fine.
> Alternatively you could use 4-400s if you wire the screen
> connectors to the grid, but they need a bit more drive.
> Mine doing very well in my L4B

-  However, in order to get enough ZSAC in a 4-400 with zero V bias, 
one needs c. 3500vdc on the anode - or apply a small positive voltage 
to the screen with a lower anode supply V.
>
> 73
> Peter
>
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>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org