>Subject: Re: [AMPS] MLA-2500B Input SWR
>Sent: 3/27/1997 8:53 AM
>Received: 3/27/1997 9:56 AM
>From: Robert, w5robert@blkbox.COM
>To: John Bradley, jmb@eden.com
>CC: amps@contesting.com
>
>I have some experience with two mla-2500B's.
>One has the optional tuned input board - the other does not.
>I have not changed tubes with the tuned input one and it gets
>1400+ keydown into a Heathkit dummy load off 120VAC line.
The only way to get this much suds out is by exceeding the keydown rating
of 350mA per anode/plate. Doing this abuses the cathode's emissive
coating and puts it at risk of flaking. To see what happens to cathodes
that are abused this way see "Parasitics Revisited" 9/90 and 10/90 QST.
Tuning up with an electronic keyer sending 50wpm dits would be less
risky--and the rating increases to 500mA per tube. However, if you have
a free supply of 8875s, it doesn't matter, Bob.
R. L. Measures,ag6k,805-386-3734
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