[Elecraft] K3 AM Power Setting: Was (no subject)

[Grant Youngman]

It wouldn't hurt to have something in the manual, but what I described is the correct way to adjust the K3 for AM operation.

In AM mode, use TUNE to adjust your external amp, NOT Transmit.  TUNE will let you get to a full 100W carrier out of the K3, or whatever level your amp needs to get to the desired PEP level.    XMT (or PTT, whatever) will change K3 power out to the correct carrier level, which is 1/4 the indicated PEP.  Load the amp to the desired PEP (not carrier) level.

You can adjust the PWR setting in AM mode when transmitting, but the K3 indicated power will be PEP -- not actual carrier power -- which again, will be 1/4 of the indicated power level.  This is set for you automatically in the K3, so you don't have to worry about it.  Trying to use 40 watts carrier out for example on a typical modern 100W PEP radio will either reduce your modulation percentage or distort and sound pretty rotten, or both.

Barefoot, you'll have (within someone's ability to distinguish) about the same power out as a Ranger.  If you're going to drive an amp to increase power, then make sure the amp can safely go key down for many minutes at the (carrier) power level you want to run -- which would be 375W (roughly) for a (roughly) legal limit AM signal.  I can push my AL-1200 that way all day, but usually don't run it at more than around 250W carrier (tuned up to 1KW to get the PEP level correct).

Grant/NQ5T

On Jun 20, 2010, at 9:21 PM, Jim HaRRIS wrote:

> 
> First let me apologize for sending out the first message without a subject. 
> My mistake.
> 
> I appreciate all the responses to my questions.  While Grants information
> below sounds reasonable and may well be correct I would like to see
> something in the manual about how the AM power setting functions.  It does
> seem unusual that I set 25 watts with AM mode selected and received a 56
> report from 1200 miles away.  That would mean that slightly over six watts
> was actually transmitted.  
> 
> Specifications of many other radio's speak of 25-40 watts for AM.  The
> specifications and owners manual for the K3 does not address the details of
> AM power.  And, I might add the same for FM.  I would like to see Elecraft
> staff address this so there is no misunderstanding.
> 
> CU in the Colorado QSO Party on September 4th, 2010.
> 
> Jim, W0EM
> -- 
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