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Re: [Amps] AL1200 on AM - max carrier?

To: Robert Logan <bob.logan47@yahoo.com>
Subject: Re: [Amps] AL1200 on AM - max carrier?
From: Drax Felton <draxfelton@gmail.com>
Date: Thu, 30 Oct 2014 11:59:20 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
And this one too...


At all times, transmitter power must be the minimum necessary to carry out the 
desired communications. 


> On Oct 30, 2014, at 10:16 AM, Robert Logan via Amps <amps@contesting.com> 
> wrote:
> 
> Thought I might mention the legal limit for AM is 375 watts carrier.  Bob. 
> NZ5A
> 
> Sent from my iPhone
> 
> On Oct 30, 2014, at 9:04 AM, Kimberly Elmore <cw_de_n5op@sbcglobal.net> wrote:
> 
> Any amp will be inefficient when used as a linear amplifier for AM because as 
> drive is reduced, efficiency is reduced. They will all generate a lot of heat 
> in this application. However, the AL-1200 should hold up well to the 
> lock-and-talk culture. In AM, PEP is 4X the carrier, Overall, you want the 
> carrier to be at 1/4 of the amp's rated PEP output. 
> 
> Assuming the driver  generates 100 W output, tune the amp for max or 1500 W 
> output (whichever comes first) with the amp in SSB mode. You want SSB mode 
> because you want the best linearity. Whether or not you use SSB or CW makes 
> little difference in the efficiency for your application but makes a big 
> difference in linearity. 
> 
> Usually, when the driving rig is in AM mode, the carrier is reduced to 1/4 of 
> the max PEP SSB output. In such cases, you should see no more than 375 W 
> carrier power (375 x 4 = 1500).
> 
> If you are trying to drive it with an older plate-modulated tube rig, you ill 
> have to be careful if you reduce the power output because the modulation 
> transformer is designed with a particular output impedance in mind. If you 
> reduce the drive to the PA, the impedance changes and you will have to set 
> the proper audio level using a scope or modulation monitor.Start with audio 
> gain at zero, bringing it up slowly. Otherwise, you risk arcing in and 
> destruction of the modulation transformer. 
> 
> Kim N5OP
> 
> 
> On Thursday, October 30, 2014 8:05 AM, Gary Smith <Gary@ka1j.com> wrote:
> 
> 
> 
> One thing for sure, run it at the CW 
> setting, use the lower KV setting and you 
> will run far cooler for a given KW out.
> 
> 73,
> Gary
> KA1J
> 
> 
>> I want to run my AL-1200 on AM for a short stint (2 hours operating 
>> time, 50% overall duty cycle). I have tested it at about 225 watts 
>> carrier output, and with moderately high duty cycle transmissions (known 
>> in the AM crowd as 'Old Buzzarding'), it gets quite hot.
>> 
>> What is the max recommended AM carrier power for long-winded transmissions?
>> 
>> Also, I'm assuming it should be tuned up for proper operation at double 
>> the carrier power.
>> 
>> I searched the list finding no real answers.
>> 
>> Thanks,
>> 
>> Tony, K1KP
> 
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