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Re: [Amps] power limiting in 8410 amps?

Subject: Re: [Amps] power limiting in 8410 amps?
From: Steve Bookout <>
Date: Sun, 4 Nov 2018 17:48:11 -0500
List-post: <>
Hello Jim,

I have several of them and it's all about the same.

Plus/minus on different bands, but quite similar.

I've had several people suggest it's because the screen voltage is only 200 volts.

73 de Steve, NR4M

On 11/3/2018 1:40 PM, Jim Thomson wrote:
Date: Thu, 1 Nov 2018 19:32:58 -0400
From: Steve Bookout <>
Subject: [Amps] power limiting in 8410 amps?

<I ask because, I have 4 of these amps in my M/M contest station and I've
<always noticed that the higher the power out, the more input it takes to
<get there.?? They tune up real nice and easy to about 1200 to 1300
<watts, with about 40 watts of drive, but to get to 1500 seemed to be a
<challenge.? Seemed like the gain would fall off, maybe taking twice as
<much power to get the last 200 watts.

<I know there is no real difference in the effect of
<the power out, but I would rather get 1500 watts out @ 45 watts of
<drive, than 65-70 watts of drive.

<73 de Steve, NR4M

##  whoa, if the  8410  requires just 40 watts for  1200-1300 w
but  75-80 watts  to get 1500w, something is amiss... as in the
8410 isnt linear under those conditions.. not even close. Are
you sure whatever watt meter you are using to measure drive
power is  dead on..ditto with output wattmeter  ?
The gain is falling off..and fast, when driven harder.
Its almost like you have entered the gain compression region.   A  2 tone
imd test  would show the effect right away.

Your gain dropped from  14.95 db...down to  12.87 db.   That’s a 2.08  db drop.

##  Does it do this on all bands ?

Jim   VE7RF

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