[AMRadio] AM Amps

Gary Schafer garyschafer at comcast.net
Fri Jan 14 12:24:41 EST 2005

3500 watts pep output would require a carrier of a maximum of 875 watts 
if it were 100% modulated.
If the amp runs 65% efficiency at full output that means that the 
efficiency must drop to 1/2 that at carrier level or around 32% for 
proper AM operation.

At 875 watts out with 32% efficiency would require an input power of 
2734 watts for carrier. Subtract the 875 watts from that and you are 
left with about 1860 watts of plate dissipation power! That doesn't 
sound like any kind of CCS class B amplifier to me for a single 4-1000.

Maybe a pair of 4-1000's?

Gary  K4FMX

James M. Walker wrote:
> In a properly designed and adjusted 4-1000A Class B amplifier,
> the approximate maximum power output in class "B" is 3.5 KW.
> That is CCS, and not ICAS. An amplifier of this output class was
> presented in a 195x Radio Engineers Handbook. The design works
> as the rig verifies, modes are AM/CW from the DX-100. Adjustments
> are left as an exercise for the student.
> Jim
> ----- Original Message -----
> From: "Darrell, WA5VGO" <hbrnut at earthlink.net>
> To: <garyschafer at comcast.net>; "Discussion of AM Radio"
> <amradio at mailman.qth.net>
> Sent: Thursday, January 13, 2005 6:35 PM
> Subject: Re: [AMRadio] AM Amps
>>Got to be CW, RTTY, etc. With AM you would either melt the tube down or
>>splatter all over the band.
>>Darrell, WA5VGO
>>At 04:49 PM 1/13/2005 -0500, you wrote:
>>>How do you reduce the drive for AM? I take it that is how you operate CW?
>>>Gary  K4FMX
>>>James M. Walker wrote:
>>>>4-1000A G.G. amplifier, 3000 VDC plate, 700 MA Plate I, 500 MA
>>>>Grid I, with 125 Watts out of DX-100 running apprx 2100 W input and
>>>>dissipating 670 watts plate = approximately 1430 watts output!
>>>>While the carrier level into 50 ohm dummy load is 1400 watts measured
>>>>and a really NICE orange glow! This is with a 200 cfm blower, air system
>>>>socket and chimney.
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