[AMRadio] Legal limit

[Rick Poole]

At 12:50 PM 1/24/2012, L L bahr wrote:

 >>>>>
>Of course non of this will make sense to most of the ham population 
>today.  It's all about me and the hell with the next guy.  Never 
>mind running my station using good engineering practices.
<<<<<

Lee, if any of that is directed at me, that is not fair.  If I didn't 
care about best engineering practices, why am I here asking all these 
questions?

Someone said something about "Bingo, I think this is what Rick is 
missing".  I don't think so.  I'm clear on the concept of tuning for 
the peak power you want (or peak power available, whichever is less) 
and then backing off the drive until your dead carrier output is 1/4 
of that.  What I'm not quite so clear on is why that results in such 
crappy efficiency.  But in real terms I guess "why" doesn't really 
matter... the fact is it does that and that's what we have to live with.

Someone else said something about "There are no out of the box 
solutions for this" or something close to that.  Someone else said 
"AM linear is a bad idea" or something like that.  I don't know why 
either of those should be true... there are amps out there that claim 
continuous key-down capability at legal limit (e.g. some Alphas) and 
others that claim full power key down capability within some time 
limit like 30 minutes (e.g. some of the bigger Ameritrons).  If one 
understands the limitations and lives within them I don't see why AM 
linear should be considered such a "bad idea" as a blanket 
statement.  The big reason I am here is so that I can understand the 
limitations and live within them.

Speaking of Ameritron, I just got an interesting email from them 
(well, an email inviting me to jump through a few hoops so I can read 
their reply to me off of their website).  I had asked them if the 
AL-82 was capable of 375 watts continuous dead carrier and 1500 watts 
PEP output on AM, which seems well within their claimed specification 
of "1/2 hour continuous carrier: 1500 watts".  Their answer was that 
the AL-82 is specified for 400 watts carrier... but only "800 watts 
modulation for continuous AM".  If it is rated for 1500 watts 
continuous for 30 minutes, why then can't it run 1500 watts PEP AM 
for 30 minutes?  Or maybe that's what they meant... 800 watts AM 
forever, more than that for times less than "forever".

Or maybe they don't understand the concepts behind AM linear, either.

This is the outfit that claims an efficiency of "nearly 70%" in both 
CW and SSB mode.

Rick WA1RKT